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Hi I'm Michelle Patterson and July's What's Neat all about soldering starts right now. The What's Neat Show is sponsored by Caboose, sharing our passion for trains since 1938. Hi my name is Ken Patterson and in this new video we're going to take all the mysteries out of soldering. This is going to be an advanced and beginners video on soldering. We're going to discuss soldering your track work and everything that goes into that. We're going to talk about soldering all the wiring on your layout and the block wires and how to go about soldering the electrical for a model railroad layout. We're going to talk about all the various types of soldering equipment. Pencil points are the primary tool that we're going to use for the track work and the wiring and then we're going to get into resistance soldering rig. A great mystery for many people but if you learn this trait you can actually make some darn good money selling models and building fabricating stuff from scratch out of brass. I'm going to show you how I took this beautiful $5,000 one half inch scale precision scale locomotive that was destroyed in shipping and absolutely rebuild the model into pristine factory new condition. Then I also take you through and I show you how I built a light tower. Actually in this video we're going to take a light tower that I've already built and repair it and I'm going to show you how to go through the process of working on a tugboat. Building the superstructure handrail steps and the top lighting and antennas and all that fabrication work all made out of brass. There's literally nothing that you can't do with brass and in this video we're going to cover all the bases and take all the mystery out of soldering. Each type of equipment that I'm going to discuss has got its own separate purposes although a lot of them can overlap. Starting with your old grandpa's handgun if you can remember the old Weller handguns the 125 watt units most people have melted a lot of railroad ties using these things but they work really good for soldering your track together. You can find one of these on eBay for about 10 bucks. Normally what we like to use is pencil tip soldering irons and there's various types of them they come with bases and fancy knobs but I like the simple ones. The larger ones are really good for O scale and almost large scale track. The smaller ones are excellent for doing HO scale track and our HO scale wiring. This is what you really need to get started with and these will last you a great many years they simply don't wear out. You can find them for as low as five or ten dollars and I've also discovered units that have got adaptable blades on them so you can use them for cutting into plastic making shingles on the side of a building anything like that. A lot of stonework you can do in Walther's plastic buildings when you're when you're super detailing them with a knife cutter like that. As we move up the scale now we're getting into the more useful units where they've got temperature degrees on them. They'll show either in Celsius or Fahrenheit how what the temperature of the needle is so in Fahrenheit about 800 degrees in Celsius around 480 degrees and these work great because you can adapt a lot of different types of tips on them. I've got a knife tip on it. I've got pencil tips very heavy tips a lot of different tips usually they come with about 10. You can buy a unit like this on eBay for about 50 bucks. Now resistance soldering rig that's what this is when you use one of these units you'll see when I step on the foot pedal switch I get instant heat in the tip of the nozzle and as you see the nozzle heats up the brass everything instantly melts together. If you use liquid soldering like I'm doing here in this video I'm putting liquid solder onto the piece of metal. I'm hitting the foot switch and you get instant heat instant bond it's almost like using hot milk glue and and this unit is absolutely usable for building brass models. If you're building brass you want that area to get very hot quick so the surrounding brass doesn't cool off and also melt and your whole structure starts coming apart. I also use the resistance soldering rig for doing garden railroad track when I've got a solder wire on a code 250 rail that's pretty heavy and any of these other units would get the rail too hot and melt the ties with the instant heat that you get from a resistance soldering rig it makes jobs you couldn't ordinarily do doable. Now as we get up higher into the scale radio check sells a pretty nice soldering rig two piece unit simple pencil tip I haven't found a lot of different types that I can put onto this one I inquired about that and couldn't find any it's got a very fine tip on it for doing electronics work so if you're fixing cell phones and things like that has nothing to do with the hobby you got a side income these are great for that this is really almost too small for working on track it doesn't heat it up quick enough but it's a great unit it's got temperature displays on it preset temperature displays and a knob so you don't have to push buttons and wait for things to get hot the last unit that I want to talk about is is the Kremel of the Krem this is a unit that's got the variable speed temperature readouts for the fine point soldering tip it comes with about 12 different size tips so the versatility is there for all uses in the hobby another interesting thing it's got is a 12 volt power supply in the front so if you're at the workbench and you want to test something test the joint test the the lines on one of your resistors you can do that with the 12 volt power supply another feature that this has got and this has become really big in the last 15 years is using air to solder with as you see in this clip I'm using the pencil tip point air to loosen up the solder on the circuit board and by doing it that way you're soldering with air you're not touching a very hot point onto the electronics and you also get an even flow over a large area so that you could take a lot of liquid solder and heat it up in a quick hurry using this unit so something new if you're into electronics soldering with air works really well I have also discovered that when I'm out on a photo shoot and I'm drying the bottom of the feet of people after I put that glue on them that tacky glue to make them stand up takes a long time for that to dry but with this gun I can quickly speed it up so I found a lot of other modeling uses out of this heat gun so that's just kind of an overview of some of the soldering equipment that's out there and that's all I wanted to discuss at this point on this tape one of the most important soldering rigs that you want to invest in is this simple pencil tip rig spend the $50 go to ebay find one of these units this is going to be the most useful pencil tip unit that you're going to find for model rariting you're going to solder your wiring together with it in this case I'm attaching jumper wires to my turnouts after I've gapped them so that I get power throughout and these are going to be DCC friendly turnouts and at the same time the points are hot all the time which is what I really like is hot frogs so that I don't lose any conductivity but for a unit like this in this example this is this is the best unit you're going to use it for your soldering of your wiring you're going to use it for soldering your rail joiners and your track work this is just a magnificent unit and it works it gives you a nice temperature readout in Celsius which is really irrelevant once you find the temperature that you like and that you want that's the setting that you're going to use all the time but this is the unit that I suggest that you invest in is one of these types of pencil tip units where you've got a body unit and then you've got a holder for the gun these work out really well like I said I use this for 90% of the work not for fabricating so much as for all of our electronic track work switching laying tracks soldering jumper wires soldering all of your connections to your circuit boards when you're making your power panels this is going to be the unit you're going to find the most useful to use now I'm using 6040 rosin solder on this it's already got the flux in it and rosin solder doesn't hurt the electrical so and in this case I'm not I don't have any wire for the acid core solder to wick up into so if I was using acid core solder I could actually do that on the track joints and it would flow beautifully but this is working really well with this rosin solder and I've already got some paste flux on the track which is why the solder flows if we didn't use resin or any kind of cleaning agent at all in the solder to clean this rail as it's soldering this solder wouldn't even stick it would not stick to the metal so because of the rosins that are in it or if I were using acid core flux on this in this case that would cause it to flow very nicely so that's what you do again with the pencil tip rig and that's what I'm using here is this this nice pencil tip rig right here to solder this track work together and in any scale be it n scale in this case I'm do actually doing n scale rail joiners for HO scale track code 70 that's the best way to do it today they fit perfect so that's how we use the pencil tip for soldering track now notice when I touch the hot probe to the track I don't touch it very long and the solder just flows right into the joint and that's how you want to use these pencil tip soldering rigs this is the best way to do this on track it's just a wonderful way to guarantee continuity and it works now let's talk briefly about block wiring the first thing I like to do is take a dremel motor tool and grind off the rail so I've got a good contact area for the for the solder to stick and then what I need to do is fish a wire through the foam generally and I use a brass tube for this sometimes I run the wire through the tube in this case I just have to poke a hole and stick the orange wire in I'm using solid strand wire on this because it's never going to bend or move I don't have to worry about breakage so what I need to do is solder the end of the wire to the rail and I like to strip that off with a rail stripper and then I like to take a pair of tweezers to clamp the rail into place while I'm soldering it with the rosin solder so that joint's done and then it comes down to the electrical side where we want to solder the switch I put rosin on the switch leads and also on the wire and a little bit of solder already on the switch and I just touch it for just a few minutes a few seconds because you don't want to melt it and then we stuff all the wires back in after everything's soldered up and it's essentially how I do my block wiring. So now in this segment of the video we're going to discuss resistance soldering rig I've got a PBL rig here that I've had for about 15 years and these things work great if you can find one of these online mused they don't break they work forever and the purpose of a device like this is to heat up the location of a brass model or a piece of brass you're working with immediately so you've got instant heat so that all the surrounding parts don't come apart and come desoldered when you're working on a project so if you're adding small details to a locomotive like this adding a bell or a new blower you can do that without affecting the rest of the model with the resistant soldering rig also this boat is built the superstructure and all the handrails and the floors are all built out of brass same same idea where I'm sitting here and I'm soldering on very small parts just like hot glue without desoldering the rest of the location so this is how the brass models are made overseas the same principle now let me show you how the device works I've got this large scale engine here that is actually a museum quality half inch scale model and this thing's got to be rebuilt because it got shipped and got destroyed in shipping and so what I'm going to do is rebuild the cow catcher and all the various parts on it that are broken using exactly the same technique that I'm going to show you on this scrap brass right now and essentially what I do is I've got my resistant soldering rig I've got my tip that will get hot and I've got my ground wire and I've got to connect the ground wire to the piece of work that we're working on in order to have the circuit of electricity run through the brass for the soldering effect to work so I'm going to clip my my alligator clip right here to this piece of brass and all I want to do is for demonstration illustration purposes is I'm going to take this circular piece of stock and just attach it to this flat stock just like that so I've got everything set up the only thing I need to do is get in there with a little bit of solder I'm going to step on this foot switch to activate it and today I'm going to use a little bit of liquid solder from the hardware store just regular old liquid solder so I've gooped on some some liquid solder right here just for illustration purposes and how this works I'm going to press down on my foot switch with my foot so I've got instant heat on the location that I want to solder let me just show you how easy this is now instantly the whole area is getting hot and just like that she's attached let me do the other side same way instant heat let it cool and just like hot melt glue your parts going to be attached this works it's a great system so I suggest for fine model building for building handrails for building can't nary for overhead wires for projects this is a very useful tool to use so look into resistant soldering another great use for resistant soldering other than just soldering brass models together I like to use it on the garden railroad track and the reason for that is it would take a soldering iron a regular pencil point soldering iron much too long to heat up this rail and by the time it did heat it up the rail overall would be so hot that you wouldn't have any more plastic spikes left on the track it would absolutely incinerate them so the key to doing outdoor garden railroad track for making my wires that jump from one section to another so have complete continuity all the way around is to use a resistant soldering rig and let me show you how I go about doing that first of all we've got to make sure the location where the wire is going to be soldered is clean and I'm using solid wire this time and that's going to that's going to be an important factor in just a moment but when you put your rosin in this case I'm using flux paste on your wire and then I would solder it but because I'm using solid strand wire I'm going to go ahead and use some acid soldering flux on this and the reason for that is because the acid flux works very quickly it flows much more smooth than the paste and because it's solid strand wire I don't have to worry about the acid flux soaking up into the wire wicking up as they call it and then the joint literally the acid would eat that joint away in about five years and you lose your electrical conductivity so because it's solid stranded wire and because it can get washed off in the rain I won't have that problem out here so simply what I do is I've got my got my acid core solder I've got a step on a split switch at the same time to activate the probe that I do the solder joint I need to connect my ground wire to the track and I also need to use this pair of tweezers to hold the wire in place during the soldering so it doesn't move I don't have enough hands to do everything because doing the solder itself is going to require both hands so everything's set up and ready to go all I've got to do is step on the foot switch the gun's going to get hot immediately upon contact and then I'm going to make contact and you're going to see this solder very quickly heat up very fast I don't have a good ground hold on keep my ground wire connected I got power now I'm instantaneously getting hot and the solder is flowing and that's it I'm done clean up the excess and I've got a good solid joint now all right just the wires on there solid and I've got my conductivity and my track can still float aesthetically it doesn't look great but functionality wise this is the way to go on garden railroads now in this segment of the soldering video we're going to talk about something where the resistance soldering rig can actually pay for itself in just virtually one project and I mean that now now I've got it set up underneath my workbench this is a spot where it's normally always set up and on top of my workbench I've got a brass locomotive this is a precision scale uh k-27 in one half inch scale and originally when this engine was brand new this engine sold for four thousand nine hundred ninety nine dollars so you're looking at a five thousand dollar locomotive and the front end of this had absolutely been destroyed in shipping when this model was shipped to me and rather than cry over spilt milk in the next 20 minutes here we're going to fix it now the problems are rather complicated on this and I'm not going to take this locomotive all apart I don't have to primarily it's the cow catcher it was seriously bent it's supposed to be the shape of this and I've re-bent the metal very closely now also the running boards are both loose and it's this is where the resistance soldering rig absolutely there's no other tool that could do what we're about to do because the whole point is to heat up the area around this brass without the rest of the cow catcher falling apart and if you look these are some very heavy pieces of brass for running boards that I'm going to have to put in there so normally what I would do is I would sandblast this whole locomotive but today I'm going to take some lacquer thinner and a wire brush and I'm going to clean up the parts the best that I can and then we're going to put some liquid solder on there and some acid core flux from pbl I really like this acid core flux now this stuff will have to be washed off so the solder joint doesn't continue to eat itself away because it's acid core but after this is all finished and it's all cleaned up and all the solder joints are in place it should be virtually as good as new it's just a matter of bending the metal and getting everything to fit the way it's supposed to and that's not going to be a problem it's just going to simply take time because you've simply got to bend the metal and work it until it's in the right position if you need a break quit take a break come back and do it again while you're fresh also on top of the cab this dome that protects the air hatch on top of the cab was severely bent and I've already kind of re-bent it into the shape that it needs to be but the attach point is going to be on the rear of the cab right here where it is completely loose and we're going to reattach that with just a little bit of solder too so let me get these parts cleaned off with some lacquer thinner and wire brush and I'll show you how we use a resistant soldering rig to solder one additional point I might be taking q-tips that are wet and wet towels just to keep the main area cool because we're going to heat this up really fast and I certainly don't want the rest of those parts to start popping off okay just a little further explanation for preparation on this now I've got some torn up old pieces of dirty sock I've got a cup of water right here so I can wet the sock and what the reason for that is I've got clamps here and I can clamp the sock or the q-tip around various sections of metal so that the whole area doesn't get too hot I might not have to do that but I'm prepared just in case now what I'm going to do is I'm going to put acid core flux on the parts where the solder is going to go and I'm going to assemble all these parts in place into position whether they are supposed to be affixed to the rest of the brass and I'm also going to put liquid solder on it in all the locations where it's going to make contact and then I'm going to heat it up with the gun with the resistant soldering red tip I'm going to heat up those locations and start to solder this that's the plan so let's see how this goes that's where the parts are going to go so now I'm going to put on the acid core flux where the parts are making contact so everything will be super clean and I'll have very good clean area for the solder to flow so liberally put on this acid core flux I'm not worried about getting it on my fingers right now I'm just worried about getting this job done and that's where those parts are going to go right it's exactly where I want them to be now I'm going to start by soldering the footboards on at the bottom and work the uh work the joint all the way across these two pieces so they solder together and I'm going to clamp this with tweezers everything's in the right position the same on the bottom and I still got to put in brushing some solder I want to do that before I get these two clamped I'm going to use this paste solder this plumber solder from the hardware store it flows really nice I'm going to put it on this piece of metal so I have an area to work from like a palette so right now we're going to pretend like this is oil paint and we're going to put this on like oil paint in locations where the pieces touch so I'm going to remove my clamp now I'm going to pull out one of these pieces here move it a little bit so I've got good there that's what I want right there and I don't know if you can see this I'm going to try to get to see what's going on here I'm putting the solder I'm working the solder into this joint right here underneath the footboards we can always clean up the solder if you get too much on after it's attached there's ways to do that with wire wick which absorbs the solder and takes it off of the model that's wick wire wick soldering wick is what they call that I've still got to put this triangle on the bottom here that it's going to be one of the last pieces to go on this is going to be very complicated to not get this whole structure too hot I need this to stick together putting the solder behind the footboards and I'm applying it rather liberally it will stick to the clean metal and the areas where the acid core solder is the areas where the paint is still on here the solder will not stick in those areas so I don't have to worry about it flowing there and the heat might bake that paint right off but after we wire brush this and clean this and lacquer thinner after it's soldered we'll be able to put a fresh coat of black paint on this and it should be perfect if I have to do a little wet sanding with a thousand grit paper to make it match up I can do that but this should look like it's never been altered all that much it should be almost as good as new because this is how the brass builder built them all right got everything clamped together where I want it I'm going to start with this first foot pad and I'm going to solder on this area here I've got both clamps holding it I've got the resistance soldering rig center that's highest setting number five I'm going to take this ground clamp and I'm going to clamp it to the workpiece somewhere on here so I get good ground I don't know where I'm going to clip that on here hold on I want to get great great electrical flow through this so I'm going to clamp it right here that should give me good conductivity we'll find out here in a second I got the foot switch on the floor everything's clamped together all I got to do is step on this and do it oh lord here we go I'm not going to hold that with my fingers either I got good contact okay good here we go I got good flow now under the workpiece there we go we got a good solder joint I'm backing off now because I don't want it to get too hot now I'm going to keep going all the way across work my way down here while this thing's good I'm going to drop it right here and I heat up this area right here see the solder flowing right between the two pieces that's how it's supposed to work just like that back off so I don't get it too hot I'm gonna work my way down right here I want good solder flow here and I've got it between the two pieces this is getting really warm now I'm gonna back off right now I've got an inch of area to just solder together I'm working my way down a little further now I hope you can see this I can't see the camera I'm trying to see this through the goggles at the same time okay here we go I'm getting a good area hot both pieces of metal good joint I'm backing off the heat now that's a good solder joint right there now I'm working my way down to the bottom footstep which is where my clamp is so I gotta move that that puppy might be hot it is very hot so that's what the water is for when I cool that down right now this is serious this is almost like welding but not quite because solder is such a cool melting point metal this little wet rag is getting very hot right now I might have to let this cool off for a minute before I proceed any further because I really don't want this thing is very hot I don't want the I want the front end to cool before I continue on so let me just pause here for a minute okay I'm picking up right where I left off and I'm working on the bottom here now so I want to get down in here and try to see what I'm doing all the rods and set up everything's ready to go I should just be a step on this and go I don't have contact hold on and here we go I still don't have electrical contact I got nothing okay I got it I got heat now all right to continue now I think this is getting hot because it's parts loose right here I need to tighten that up or else I'm going to lose my electricity inside of the resistance of this loose nut all right that's tight put my clamp on see if I got contact I do all right let's do this let's get this hot get in this area hot here and now I'm working on both pieces and I've got a good solder flow right now underneath the lap both pieces are soldering together sweet I'm going to work my way up to this joint right here here we go right now that's a good solder joint right there it's flowing beautifully in between the two pieces of metal the flux is just drawing the solder right in I'm working my way up now this puppy's going to get hot so I'm going to back off here at this last part and I got a good solder joint right there see that isn't that nice all the way up the workpiece all the way up make it smooth good joint right there I'm going to get me some solder and actually feed some solder into this while I'm doing this I want this to hold look at that that's beautiful joint right there flowing very nice onto the workpieces this is just working out nice there's another nice joint the solder is flowing between all the workpieces right now everything's working out real sweet this is nice there you go look at that flow right in there that'll be strong as brand new let me see I might take a file to this after we're done with this I'm working on top now I'm flowing some solder in between those parts you couldn't do this with any other tool look at how that works now this model is going to be just this is how they build them in China this is how they build them in the factory okay so let me brush off these parts and look at them and then we've got to apply this triangle to the bottom which will be really easy to do as you can see so far it's working out really nice got a little bit too much solder down here I've got this part cleaned off the bottom of the pilot which is going to fit right into those grooves real nice but I've got to clean out some of this excess solder right here and that'll allow that part to fit in there real nice and we'll clamp it in place put solder on it and I'm going to start at the rear and then work myself around to the front point and I can bend the metal and work my way around as I go so I'm going to start right here and I want her to be in place just like that I'm going to let you watch me do this real time so that you see from start to finish how this is going to work out I'm going to start with my paint brush and I'm going to start applying the acid core flux where my solder joints are going to be I want all this brass clean and I want good flow here and I'll get that with this this is the best flux in the world pbl soldering flux I love that stuff I use it for all of my big static models when I build brass scratch build stuff all right I'm going to put this part in place I'm also going to put the flux underneath that only in the corners where I'm going to work it right now worry about the rest of it later as we work around the front I'm also going to squeeze on some solder although I'll tell you where there's a lot of solder in there when I hit the foot switch what's in there may already flow but I'm just going to ensure my flow and just squeeze a little bit of excess solder in here not too much not too little just kind of fill that area see that just a little solder right in there now I'm going to put the piece in place I'm going to clamp it the best I can tweezers just like that there's exactly what I want very happy with that very happy with that okay I'm going to ground the resistance soldering rig with my clip and I'm also going to be ready with a little solder on the side here a little wire solder and I'm going to start right here at the top there's a piece of plastic here to protect the train I'm going to pull that off right now let's protect the train from rubbing on the rails and shorting out see if I got heat I do okay let's do this the solder's flowing in the joint beautifully look at that plastic melt we'll put some clear tape there there you go another good flow everything flowed nicely right there I want to pull this in with my pliers just so this gets centered in the right spot heating it up and pulling it in with the pliers at the same time pinching it into position heating it up and I'm pulling it down I got a good joint right there good good solder joint right there good flow right there okay I'm going to let it set before I let it go with the pliers because I've got that metal right where I want it to be just like that now we're going to do the one on the bottom the same way the same way on the bottom joints I'm going to come in behind with my solder on this one ready here we go foot switch touching my solder just a little bit there come on baby get hot there you go there you go I got good flow between the parts and it's permanent now I'm going to work my way around to the front I'm going to have to move the camera here just so I can see what's going on for a minute into the front this is really nice the way this is lining up I want to make sure this metal lines up real perfect so I'm going to take my pliers and just squeeze everything just in the position here where it should go let me bring you in on this so you can see what I'm doing here I'm trying to get this lip to line up right with that and I need a bigger pair of pliers I need a little brute force here I just want to gently squeeze that just in the place like that there's no reason to make a mistake here we're in control of everything I want to get this just right and that is just right that looks good see I'm squeezing it into position just metals bends real soft that's why brass is such a joy to work with if I can get a solder joint just like that right there I'll be a very happy camper I'm going to put on my flux you're here with me real time as I'm doing this flux is in position and I'm going to heat this up I'm going to touch my solder to it at the same time that I'm heating it up and clamping it with these pliers with my fingers all at the same time I can do clamps that that's a good joint right there that's what I want I'm going to get on the switch here and just fill this bottom area with solder ready here we go just a little bit right there's perfect right here just a little bit there you go look at that beautiful it's flowing nicely all in a joint look at that it's perfect that's exactly what we want right there and just work your way all the way around to the bottom here of when you've got this to go I'm going to flip this engine over and look at it and bend it just right okay this is the last part now to do I just need to run a bead of solder up this joint right here and this cow catcher's finished she's all done so I'm ready to go I've got everything exactly bent where I wanted I've just taken a little time with the pliers here and worked it and I'm not even going to put any liquid solder on it this time I'm just simply going to use my bead of solder and work work right along the piece without blocking your camera view if I can do that at all possible so here we go I'm going to start right here foot switch and I got solder a little bit too much right there that's okay a little wire wick I can take that off a little more foot switch solder work my way down foot switch solder okay now that's it I would say that if I clean this part now I give it another bath and lacquer thinner real clean and then all I've got to do is uh paint it that's pretty much it you've got our part on there good and solid all the pieces are back together again very heavy pieces of brass and it's not going anywhere that's not going to break this is a this is pretty much fixed right here and that's how I take a resistant soldering rig and absolutely repair the front end of a brass locomotive I'll take the file to this clean it up real nice and then paint it and I think we're going to be perfect I'm also soldering the protective hood for the cab roof vent same way I've got the solder in the joint I've got everything fluxed with acid core rosin and I got good solder flow just like that I got good joint right there too perfect so this is tacked on permanent so a little bit of thousand grit sandpaper smooth it out a little bit clean it up and I'll airbrush the roof and I'll airbrush the pilot both at the same time now now I finish before painting and clean up everything with a Dremel wire rotary brush I go over everything and just any loose solder any loose resin anything that doesn't belong there comes right off the wire brush real sweet and now I'm ready for one more wash with a lacquer thinner and a cloth and then it's time to uh thin some scale coat paint and paint this okay I've got an airbrush mixed with some scale coat black paint at scale coat one lacquer based paint I really like that on brass it's I've been using that on brass for 20 plus years and it works great so I've got the model sitting here in the spray booth I've got my airbrush ready to go with 20 pounds of air pressure and all I'm going to simply do now is just put an even coat of spray on this the paint is thinned about 40 almost 50% thinner and then 50% paint so you have a smooth coverage the key here is to be smooth you want it to look as factory as possible and this will look at how beautiful that's looking I want to turn it around and I want to do the underside as well this thing weighs about 40 pounds right down here the same way I'm avoiding the wheels this airbrush gives me very focused spray so it goes only where I want it to go looks very nice that pretty much fixes that I'll tell you what it looks just as good as new now I'm not going to bake this whole engine I'm going to let this thing set for a good 24 hours and let this paint cure but that is pretty much the way you'd want it to be if you're going to fix it it looks factory it looks brand new it looks very good and we've done that with the resistant side ring rig you couldn't do that without any other this is the best tool to do that with and if you get talented at it start repairing brass or scratch building brass you can literally make some money with a tool like that and this is how our finished soldering job looks this thing looks factory new a couple dents prototypically accurate in fact if you really want to talk about the cow catcher but I think the thing looks absolutely fantastic that's the magic of being able to use resistant soldering rigs you could take a locomotive like this it was literally on its death bed and bring it back to life the cab that section came out pretty good so we've got pretty much a finished locomotive now it looks decent now remember you're going to use rosin core solder for doing your electrical work you're going to use acid core flux rosin core flux acid core flux to do your building scratch building brass pieces I like to use the soldering wick wire for removing excess solder because when you hit the heat to this wick it in fact absorbs the solder just sucks right into it because the wick is impregnated with a lot of a resin a rosin so that it soaks in I really like using this rosin core solder a roll like this will last you virtually your entire life I've probably have had that one for 25 years and I like to weather my soldering joints using microengineering's weathering solution when I'm doing track it helps darken that really shininess so once you master this you can build a lot of really cool things with either pencil tips or resistant soldering rigs like this 110 foot light tower that I built that needs to have a little repair work done to it I can see but this is something that I built when I first got the resistance soldering rig and it was in a real model journal article a long time ago okay so let me show you how to repair this light tower because it's it's pretty beat up and it really needs work first we've got to clean off the area where we're going to have to do all the soldering and normally what you would do is you would take a wire brush and some lacquer thinner and simply brush off the part and clean it but I want to show you another tool that's really helpful to add to your arsenal of tools when you're working with brass and that is a sandblaster I picked up this north coast prototype model sandblaster about 20 years ago and I've got a vacuum attached to it where I can suck the air out of the sandblasting unit while the sandblasting is going on so let me show you how we're going to use this tool right now to fix this piece of brass I've got 60 pounds of air being delivered to my sandblasting unit and I know you're not going to be able to see inside of this because it really fills up with dust when I do this I also have the vacuum and I'm going to turn that on right now and sandblast this unit and just like that we should have something that's clean enough here now I'm going to wash this off in water but this is the brass you can see the exposed brass now let me get this to focus you can see how it's cleaner now we're going to sit over at the workbench and attach these pieces that are broken off and we can use a resistance soldering rig for this project or we can use the pencil tip I'll show you how to do both so let's talk about how we're going to fix the light tower now notice I've got this in a panda vise and the reason for that is because sometimes I clip the alligator clip to the vise itself and then I'm able to get electrical conductivity through the whole model but in this case I've got the alligator clip set up right here on the end of the structure and I've got the top all set up where we can start working fabricating and rebuilding this now there's no magic to this we're just going to do this one section at a time because this thing is really messed up on top it must have gotten stepped on or crushed under something I'm putting just a little bit of liquid solder on and I want to just get this first L piece to be in a position I also want to put on some acid core pbl flux on here because that'll really help it flow I've got the resistance soldering rig set for a lower setting I'm set for three on this because it's very small material I've got my clamp in place and I can actually hold this with my fingers as I do this just like that little heat just like that and that's the first part attached now I'm going to work on these corners look how messed up that is this is really a simple fabrication actually it was really easy to build this at the time I recall that it just took time putting just a little solder on the parts here I'm going to work in this corner right here next once this is in place this will be structurally more sound so there's just a few joints here to fix now look I'm going to put the solder I'm going to make sure it's right where I want it there's where I want it now I'm going to hit the switch just like that so that's fixed work our way all the way around piece by piece making sure all the parts are bent just right I don't have this thing fixed in no time nice thing about brass I just it's soft it's easy to work with I'm putting this joint on right here a little solder a little solder on this joint here too this is like that I just want a little bit on there I don't need very much this is how you fabricate brass and I'll tell you what it's permanent and there isn't anything you can't build in brass it's a wonderful medium to work with I'm on it I'm holding this with my fingers now because I'm far enough away where it's not going to get burnt and that's attached so this structure is slowly getting rebuilt much stronger now and just keep working my way around and we'll have this thing fixed in just a few minutes doing just what I'm doing looks like a little bending going on here we'll have this thing back together if you look at the next joint I want to solder here it's actually got enough solder on it where I don't have to put any solder on this joint right here all I simply need to do is put a little flux on it and drop some heat on that and I'm positive that there's enough solder in there already where it'll flow very nicely and I just lost my continuity because the alligator clip fell off let me put that back on the model I'm going to put the alligator clip right up here and now I'm going to step on the switch here and just do this attachment right there one two three and that's it she's attached and that's that's permanent that's not going anywhere and just like that the light tower has been sort of refabricated and it's fixed it's repaired and you couldn't have done that with another another tool I didn't use a pencil tip on it because really in reality the resistance resistance soldering rig is the best tool for doing this it really heats up that small area quickly whereas a pencil tip would have probably gotten some of the other parts heated up and then we'd be coming apart again now one suggestion I've got for you is to build a platform and what this is is this is a platform with a piece of brass on top okay and it's got a piece of brass it's soldered to the top coming off the side here so I can just put my grounding clip on this when I'm doing my resistance soldering and this piece becomes grounded so that I only need to use my pencil tip when I'm soldering very fine detail for example look at these photographs of this tugboat remember the green tugboat we talked about that I built all the stanchions handrails in the top with brass well using the resistance soldering rig and using this brass table that I've just described to you to build out of a block of wood and putting brass on top you can see where I only need the pencil tip in small areas the alligator clips off to the side my flat surface is grounded so I'm able to solder on the lights the antennas the handrails the roofs angle all of that was carved out of a sheet of brass and you know soldered all the parts onto it look at the handrails that I'm building here in this photograph these handrails are sitting on top of the flat grounded surface so that I can solder them together solder the steps on solder the individual pieces on using a low setting on the resistant soldering rig and the the flux the acid core flux for this you can see I've got my solder wick down there in a corner here's another shot of the setup with the boats cabin put in place in the center of the steps in the superstructure that I just soldered together so there's a lot of really cool things that you can do and there's a lot of nice kits on the market here's a bridge from john pilecki structures now he doesn't make a show scale structures anymore but he's making o scale narrow gauge structures now but this is one he made an h o scale bridge and there's a lot of products on the market and look at the beautiful detail of these bridge parts so once you get good at soldering it's just a matter of repetitiveness and I imagine this would actually go quicker than you think once you start getting into building all these bridge girders in order to put together this 200 foot long h o scale bridge so that's the kind of neat stuff that awaits you just check it out experiment think about what you'd like to build get some really nice solder equipment and just pretty much you know mess around with it at first I'm sure there's a lot of other information that you can find in old articles and magazines on how to apply soldering stuff to the hobby but this will give you a good general round you know a lot of information here that's going to help you go a long way with regards to building things out of brass and being able to solder your wire do your track work and repair models that need to be fixed so I hope this helped you this soldering video um happy soldering all of the model railroad products seen in this episode of what's neat are available through caboose in lakewood colorado or order online at my cruise dot com


All right, our first question is from Silverall training. What are your thoughts on the afterburn effect of exercise aka epoch? Do you really burn a lot more calories after a hit workout compared to what one would burn doing it during a low-intensity Steady-state cardio workout. Did I share did I share the article with you guys? I think he did I did didn't I share it on the show. So just like a couple weeks ago Men's I think it was men's health. I want to say it's men's health that came out with it Duckin fact-checked me. They they were hammering orange theory about this in fact cuz that was our big selling point Yeah, in fact orange theory has changed a lot of their marketing because of that which Ironically if you go back if you've been listening to mine pump long enough This was the bone that I had to pick with them way back when I was working with them was we came in of course Just like a typical company start working with them they have their whole training process and I'm in there with a lot of these like green trainers and they're talking about You know epoch and how amazing it is and I'm sitting back there going like really come on We've already we have we've already dispelled this. It's not even that that's not that big of a minuscule No, but they had built at that time their entire hype was around these the benefits of epoch and like how revolutionary it was and I'm and so they had they had the first few years that they had came out they had Marketed to this quite a bit and they've already redacted a lot of the stuff that they were saying before because of this and men's health Came out not that long ago. There it is right there. Yeah came out not long ago and was right It was just about a month ago. So they came out and they've been hammering them Over this and so yeah, the answer is no the epoch is I think it was in the 70s or 80s When it first came out when they first started doing studies around it. It's negligible I mean we're splitting hair difference on the benefits of that and so when you hear people talk about it Makes me chuckle it's based on a false paradigm of fitness and that's the this paradigm that the benefit of exercise It comes from the calorie burn while you do the exercise. This is a false paradigm, right? So people think okay, we learned a long time ago that in order to lose weight You need to create what's called an energy imbalance in other words You take in less calories then you burn or vice versa, right burn more cows you take in that means your body has to tap Into fat in order to make up the difference and you lose weight and so the paradigm was created that oh in that case Let's exercise a lot burn more calories. That's gonna be a very effective strategy for fat loss It's a terrible strategy never works for the following reasons number one You don't burn that many calories when you exercise. I don't care how hard you work out You're gonna burn maybe in an hour or 400 calories 500 calories. You may think oh, that's a lot of calories No, it's not four or 500 calories. You could eat and five you could drink that in five minutes It's not much it doesn't make that's a losing strategy It's a losing strategy So and in here's the other part if you're constantly trained to just burn calories your body is a very good job of Adapting slowing down its metabolism in many different ways even affecting the rest of your activity throughout the day to balance it out So what ends up happening is you burn 500 more calories a day? Let's say you work out every single day real hard for an hour Well, you find over time as your body actually balances out and you stop burning those extra calories Here's the paradigm that you want to focus on okay? You want to focus on this paradigm? What kind of adaptations is this exercise causing to my body and then what are those adaptations? What do they do for me? What's the benefit? Yeah, what's the carryover? That's it So if I'm training for endurance, what are the adaptations while I get more efficient with calorie burn?  I Build more stamina that could be good if I'm an athlete or whatever What about resistance training lifting weights doesn't burn a ton of calories But what it does is it through the process of strength and muscle building it actually speeds up the metabolism So epoch although it is splitting hairs like Adam said doesn't burn them any more extra calories It's built on a false paradigm. So forget your calorie burn during your workout. That is not important at all Look at what adaptations your exercise even for the after because that that's what it stands for right? It's the it's post workout that they they try and in tout is that okay? You burn more calories. Yeah. Yeah, if your body, you know would burn on it Let's just say for hypothetical reasons it was 2,000 calories day when you do hit training it burns 2,300 calories in addition to what you burn in that one They're inflated numbers and they're and they're false time and not to mention too and we talk about this on the show all Time that don't matter what modality of training that you are doing the body adapts to that right? So any of the it's novel it's a novel stimulus that your body is responding to right away And yes, there's probably that benefit that you see with an extra amount of calorie burns But that's a limited window your body is going to get very adapted to that and then start, you know Slowing down the metabolism as a result. Yeah, so here's the here's the paradigm you want with exercise Does this improve my health? Is it improve my fitness? Those are important and also is this going to get my body to change in a way that's going to cause my metabolism to speed up So that I burn more calories all the time not requiring an hour of intense exercise And the but a form of exercise that does it is traditional resistance training So if your goal is fat loss or weight loss or maintain a lean body like most people Then focus on the adaptation. Don't focus on the calorie burn during or even after the exercise


Welcome to this lecture on digital communication using GNU radio. My name is Kumar Appaya and I belong to the Department of Electrical Engineering at IIT Bombay. In this lecture, we are going to have a brief introduction to wireless communication and OFDM also known as Orthogonal Frequency Division Multiplexing. To give you some context of why we are going to this topic, in the previous lecture you have seen that if you have a channel that has an impulse response that affects your performance. One issue that you will face is that you have to perform equalization at the receiver. Now what if you could perform some bit of equalization right at the transmitter even before sending it, sending your signal and even without knowing what the channel is. So in that context OFDM is a nice way by which you can parallelize the channels and you end up with a very easy equalization process at the receiver. We are going to do that but I will first motivate it with a simple channel model for the wireless system. So we are going to just look at a simple approach to looking at wireless channels. Let me just give you a caveat, it's just not for wireless but the same kind of modeling approach can work for several channel models including optical channels or underwater fiber cables, underwater communication, free space, all those things. But wireless is just one motivation, it works for several other systems also. The key idea is we will be looking both at the time and frequency picture of the channels. We will then discuss the frequency response and the frequency selectivity which basically means how the channel behaves differently for different frequency ranges. And finally, we will present orthogonal frequency division multiplexing, there should be frequency over here. Orthogonal frequency division multiplexing as a pre equalization technique, in other words how it simplifies the equalization process at the receiver is something that we will see closely today. Now if you look, if you remember from your electromagnetic spectrum, this electromagnetic spectrum is taken from Wikipedia, you can just check that the visible light spectrum is between 400 and 700 nanometers, between 400 and 700 nanometers that is the visible spectrum. Now when you look at the frequency picture or the wavelength picture that tells you the kind of signals that you can come to expect, below 400 nanometer you have really high frequency and low wavelength signals, these are typically ultraviolet and X-rays. But most of your communication systems operate in the infrared region, that is if you look at something like 10 micron, 100 micron and so on, that is where if you look at say something like a 1.5 micron and so on, that is where optical communication happens. If you keep going and generally people switch to the frequency notation, if you look at several tens of megahertz or kilohertz, that is where a lot of wireless communication happens. Let me give you sideways picture of the same. Now if you look over here in the frequency picture, when you have these kinds of frequencies, so when you have something like gigahertz, this is gigahertz and tens of kilohertz, you have radar, radio, TV and so on, FM radio and when you go for some of those frequencies that is where propagation in air is very effective, that is you can essentially send signals at those frequencies or wavelengths and that is where the signal propagates for long distances without a significant loss. Now if you look at why you know you choose those frequencies or why you choose one frequency over the other, there are multiple choices of course. One is policy, for example the government may tell you to use only this particular channel or the government may say you have to pay for this particular frequency usage and you may choose based on that. You have to decide based on propagation loss, how much energy loss happens if I signal at that particular wavelength or that particular frequency. You have to look at the reflectivity of the waveforms, that is you will have to see how much of reflection you can encounter and sometimes reflections are good, sometimes reflections are bad. You have to look at attenuation in the atmosphere meaning propagation loss is one way to look at it, but in particular depending on atmospheric conditions you may face different losses at different wavelengths. For example, certain wavelengths are affected significantly by the presence of some parts of air's oxygen, some parts are affected because of water vapor, some parts because of foliage that is the presence of plants and so on. So some wavelengths are more preferable over others depending on the environment in which you want to deploy your communication system. Finally, you may also be interested in the directivity or line of sight that is you may have to look at whether the receiver and transmitter have to face each other directly. An example where you don't need line of sight is your traditional wireless communication system where you have something like your GSM or a 4G based handset. This handset works inside the building even if you don't have a direct visible path from your phone or from your device to the base station. Some for example, modern millimeter wave systems are designed in a way where you have to have the line of sight. They have to see each other in order to communicate effectively. That is something which you have to keep in mind. So let's look at the so frequency domain picture. So I'm going to look at the frequency domain picture and from the previous exercise we have been looking at the time domain picture where you had inter-symbol interference and so on. So you had inter-symbol interference then you know the channel became channel was no longer an impulse like channel did not have a flat frequency response it had some different frequency response. Let us just look at the frequency response picture directly this time because it will serve our purpose well to understand the new pre equalization technique that I'm talking about. So you have to select the appropriate frequency range based on what frequency you have the license to or permission to radiate on where there are losses which are acceptable where you have a transmitter receiver radio that is acceptable and so on. Finally you have decided on a frequency range. Let's say that you choose between you know around FC and let's say FC plus or minus W by 2 you have chosen. This is the band at which you are going to signal. Now obviously the moment you start signaling let's look at this particular thing as a baseband signal a flat spectrum means there is no data. See you chose a sync pulse or a root trace cosine pulse or something and you put data on it. The moment you put data right it's not going to be flat but the channel if you want it to be flat ok you are happy because the data is going to go through without any issue. But the problem is that channel ends up being not flat why? Because there are some reflections there are some losses at some frequencies more than others there are some frequencies which get reflected and come back and so you typically never have a flat channel. The non-flat channel is essentially the same as having inter-symbol interfere or some other or some other effect you know. So typically we hope it's a linear transformation but that's what we saw in the previous set of lectures also where we were discussing equalization that whenever the channel performs some transformation on your waveform then you have to undo it by performing some filtering called equalization. In the same way you have to look at this particular non-flat channel response as having as causing essentially a problem which needs to be equalized. Now in the baseband picture I'm calling it HB the baseband picture has let's say that you did you know you had your signal at FC and after the passing through the channel you brought it back to baseband the flat channel is not flat. One approach was to use your linear equalizer such as MMSE or your zero forcing or one of those adaptive equalization techniques to bring back the channel performance. But the receive typically receiver has to somehow learn and correct for the channel. In this case because the channel behaves differently at different frequencies we call it a frequency selective channel. This is a very commonly used kind of nomenclature frequency selective is the same as a channel that performs some filtering some non-trivial filtering of course scaling just if your channel just scales the input then that's not frequency selective. If it behaves differently at different frequencies we call it a frequency selective channel. So frequency selective channels you know you know behavior has to be learned carefully. Now let's look at a traditional wireless channel a typical wireless channel let us say around the several hundreds of megahertz to a few gigahertz. You can think of it as say 800 megahertz to about you can say two and half or three gigahertz you can say this is the behavior. So if you look at hundreds of megahertz to around five gigahertz in fact signals get reflected multiple times before they reach the receiver. The same model essentially carries over to other frequencies as well but in other frequencies you may have more or less of some impacts that's something which we are just going to say. So let us suppose that this is something like your cell phone which you have inside your building and it is not necessarily facing the base station. So this is your base station this is your cell phone. So typically the signal doesn't come directly it gets reflected it can get reflected from some building it can get reflected from some wall it can get reflected from some tree it can get reflected from the car which is going on the road or something like that. Notice that some of the objects that I talked about are static some of the objects that I talked about may be moving. By the way you must remember one thing if you think about something like a building right a building which is short may be okay but if you have a building which is very very tall then buildings also have some sway they also move a little maybe by a few maybe millimeters or centimeters you can say a few millimeters centimeters of movement is not much but a few millimeters centimeters of movement is actually significant in if you're dealing with signals which have tens of centimeters of wavelength which is essentially what you are you know these signals are see if you look at 1 gigahertz right 1 gigahertz is about 30 centimeters of wavelength if I'm not mistaken you can check. So that means that the environment around you essentially changes. Now typically you don't get one reflection you get another reflection from another source or the same from the same source at different points you get different reflections and you have another reflection as well. So what you end up having is this you have transmissions that reach you maybe or maybe there is a line of sight maybe there is not but you get these reflected copies also. Now typically the problem is that these reflected copies take a long time for you to get them in other words if you look at the first copy that comes at sometime second comes second one comes with slightly different gain slightly different delay the third one comes with a slightly different gain slightly different delay and each of these essentially start adding up and you have an effective impulse response that the channel produces at your system. So our aim is to handle this impulse response somehow learn it and correct for it and that should be the goal of your system that is what we've been seeing also. So you have generally in this case you have written two parts you may have 10 parts 12 parts 20 parts depending on the system that you're dealing with you more you may have a single direct path and you can ignore all those there are various kinds of scenarios that you can deal with. Now this frequency selective perspective okay now these this non-uniform kind of gain pattern across frequency is induced by those parts if you had only a single path then you can say it's a flat channel because you don't have any other gains but the moment you have one path and another delayed and part with another gain other delayed part with another gain then you have to handle this frequency selective channel. How do we do it? Of course perform some zero forcing or MMSE or adaptive equalization but what else can we do? What if we had a picture where we could divide the channel into you know this is the bandwidth essentially let's say this is minus W by 2 to W by 2 in the base band what if we could divide it into several smaller narrow band you know narrow band channels that is what if we could break it up into several smaller parts you break it into several smaller parts then there is a significant advantage what is the advantage if you split the channel to several smaller parts we can make an approximation the approximation that we can make is we can essentially assume that the if you if you take these narrow paths to be narrow enough you can assume that the gain is constant within that range of course you may argue that you've drawn it in a way where it is not but if you take it in a very very narrow manner see the channel is induced by a natural process and it doesn't have any abrupt changes in the frequency domain it moves very gradually if you can break it into smaller parts within each part then you can assume that the gain is roughly constant right and therefore within each part the gain is constant then you don't really need a an equalization which takes into account inter simple interference and so on why see if you the problem was if you had a wide bandwidth with a wide bandwidth you had to have this equalization to correct for the gain but if you make a very very narrow band channel then by the time in the frequency domain the channel variation is visible it's very very little it's very flat so an approximation that the channel is a flat works very well or in the time domain picture for that narrow band channel impulse response is close to just something like a delta there is no real multiple parts and so on you divided your frequency selective channel into multiple frequency flat channels combination of multiple frequency flat channels okay this looks like a good trick how do you do it the intuitive way is for us to use much much narrower pulses right for example sorry much much wider pulses rather so for example if you use the sink or a sink or a raised cosine or a root race cosine rather you would have chosen it based on this minus W by 2 to W by 2 that is what you would have chosen now however that that you know that means that you will have to then use another sink or another you know root race cosine with the same which operates at a slightly neighboring frequency in another name for this is called frequency division multiplexing that is essentially let me just correct this you're essentially saying rather than use my other news my this channel I'm just going to use this particular channel this narrow band channel then I'm going to use this narrow band channel and this narrow band channel each with a different small f's fc let's say so to speak right so you're going to use this you're going to use this you're going to use this and you're just going to shift them in the frequency domain by ever so slight amounts and this combination gives you what you want now that's one way so if you recall the way we signal was x t was summation b k p of t minus k t our p was the effective effective pulse that takes into account both the transmit pulse as well as the channel now this p of t determines the bandwidth usage remember the bandwidth usage is determined only by gtx because gtx convolved with p cannot use more frequency than gtx convolved with the channel rather cannot use more frequency than gtx because it's an lti system and whenever you perform convolution you don't you can never expand the frequency footprint so one approach is to make p of t wider which is what I said right if you make p of t wider and wider in the frequency domain it becomes narrower and narrower but that is a little cumbersome because you have to create multiple such parallel you know parallel streams of data which are then modulated so that they are placed exactly there you sort of read multiple radio frequency translations and so on right because you need to essentially take one part put in the next put the next at the same gap put next in the same gap and so on we don't like that approach is there a simpler approach so one approach is very simple why don't we just repeat b0 multiple times b1 multiple times okay now this sounds a little strange I'm saying use the same p of t that uses your bandwidth between minus w by 2 and w by 2 and you start repeating b0 b1 multiple times then that results in a slightly lower frequency usage pattern how so let's just do this exercise once so now let's say that hypothetically let's say that I have a sequence consisting of b0 b1 b2 etc and I now translate this to sequence that uses b0 b0 b0 b0 and then b1 4 times and so on okay hypothetically I mean you may argue that I'm now just making the data rate one fourth I agree with you but we will handle that eventually let's just live with this so I'm essentially repeating bk 4 times let's say what happens to the spectrum usage let's say that I use let's say that my p of t is essentially sync of t upon t which is equal to sync of w t okay because my w is one upon t let's say hypothetically now if I use if I look at bk sync of t plus let's say b0 but I'll write bk plus bk sync of remember I'm sending bk again with a delay of t plus bk so the same bk is being sent 4 times this means I can also assume that I have an equivalent p equivalent let's say p prime of t is equal to sync of t upon t plus sync of t minus t upon t plus sync of t minus 2 t upon t plus sync of t minus 3 t upon t okay I have this is my equivalent p of t and if you now look at the effect of this what is the what is the spectrum of this p of t so sync is between minus w and w so what about this so this p prime of t is equal to sync of w t convolution okay delta of t because there's no change plus delta of t minus capital t because I delayed by t because delta of t minus 2 t delta of 3 minus t minus 3 t so what is my p prime of f this is going to give me this rectangle minus w by 2 to w by 2 multiplied by what am I multiplying it by 1 plus e power minus j 2 pi f t this is my continuous time Fourier transform plus e power minus j 2 pi 2 f t plus e power minus j 2 pi 3 f t if I now simplify this a little bit okay I'll just do this part this is going to be I'm going to take e power minus j 3 pi f t common so I'm going to get e power j 3 pi f t plus e power j pi f t plus I'm going to write this term next e power minus j pi f t plus e power minus j 3 pi f t this is equal to e power minus j 3 pi f t I'll put 2 outside so I'll make this a cost make this a cost that will become 2 times cost of 3 pi f t plus cost of pi f t if I apply the cost a plus cost b formula okay cost a plus cost b I'll get 2 times so I took the 2 outside made it for cost of a plus b by 2 so 3 pi 4 pi by 2 2 pi f t cost of pi pi f t now if you look at cost of pi f t right cost of pi f t where does it go to 0 the first 0 occurs at when this is pi by 2 so I'm just going to write pi f t so it's like pi upon 2 by pi t is equal to 1 by 2 t so now okay let me just so this means that let's let's do this more carefully apologies so cost pi f t is 0 that is when pi f t is equal to pi by 2 okay so that means my f is equal to pi upon sorry I just take this pi away 1 upon 2 t okay so now let's look at the spectrum okay if you now look at the spectrum original spectrum was between minus w by 2 to w by 2 okay now you saw that the original spectrum was close to 1 between minus t by 2 and t by 2 now it so happens that this spectrum is going to go to 0 over okay sorry the this is fine I must look at this one also if you look at the 2 pi f t 2 pi f t is equal to pi by 2 sorry so that means f is equal to 1 by 4 t so now the problem is that you're going to get a spectrum that goes to 0 over here in other words you essentially said that the spectrum lies only in this region because it goes to 0 over here it's almost like you have used one fourth of the spectrum now the key idea with this is if you now use another spectral component that occupies the neighboring part another one that occupies the neighboring part can you fill in four frequencies over here now it turns out that you can and this is what leads to the concept of orthogonal frequency division multiplexing so the key concept is if you if you now repeat your symbol four times then you essentially make the spectral usage one fourth this is intuitive from your DSP also if you repeat your signals you reduce the spectral footprint of course it's not like this one fourth it's actually like this but still good enough and we will see that the interference related issues are not there so what we will see is that from the next lecture onwards we are going to formalize this notion and build this into what we call orthogonal frequency division multiplexing and this will translate into several benefits in terms of your equalization process at the receiver thank you.


Good evening and welcome to NewsClick. This evening we have with us Gurpreet who is one of the co-founders of the store called People Tree. Hello Gurpreet, welcome. So we are here today to talk about some of your designs which were plagiarized by a big international brand called Christian Dior. So how did it come to your notice that Christian Dior had actually stolen some of your designs? Actually it's not designs, we've actually taken one design and it came to my notice because a friend who's a partner in printing, I mean we do block printing together, natural dyeing block printing in Rajasthan. She watched me an image of the cover of Elle magazine on in which I mean there's Sonam Kapoor wearing a Dior garment gown and the print is almost a complete take off of a print we have been doing for 20 years you know. So somebody else had what's happened to her and she in turn forwarded to me and that's how we came to know. So and what was your reaction to it? Well of course I mean I was very shocked. I was completely surprised that such a big company needs to take a design of such a small little you know setup that we are. We are mostly really not in big business neither are we in the big fashion industry that is not our thing at all. We actually printing and design are actually part of a wider philosophy of work that we do. Now we don't do only garments, we do exhibitions, we do museums, we do book covers. So we are luckily a studio really. The outlet people tree that is a shop is just one avatar of ourselves right. So it's very surprising that such a big company and can hire so many designers should be interested in this. But on the other level I realize it's a very good design. It's a very powerful design and we have always been ahead of our times. I mean we are doing a design which is to do with yoga where before Modi and Co started making a big racket about it because yoga we realize this part of our philosophy is part of something that people practice and do in India. And I guess for Dior maybe it was just oh a great design you know and yoga is very popular now and every Indians very proud of how we do yoga and all this great money making thing. So I guess that's what they did but I am very shocked. You can make they could have made their own design anytime. So I don't own yoga, I don't own yoga prints but this one is such an out and I would say copy that it's unmistakably so you know. So there's no if and but like thing about it. Even so even with the color I mean the color that that particular dress I have no idea which other colors they've done it in. But the picture I've seen of the cover of that magazine it's it's a red color and other people have posted posted us pictures of models wearing it abroad on the show on the runway you know. So it's very much part of the 2018 runway correction and it's the same the same you know these two figures are very much yes they put in one or two other figures but this expression of this man's face is unmistakably if you see the what they have used it's unmistakably this one. And have you been able to get in touch with anyone at Christianity or what has the action been from from your end? Well the thing is straight off of course there was a lot of controversy all our friends who know our staff and others who don't know but don't know of us and many you know independent designers, entrepreneurs and all they're very shocked and there was a discussion on social media that you know should it be just through shaming on social media should it be some kind of other actions some legal notice some message some mail so this little thing has been going on even now a lot of articles have been written and so we are considering I mean and some people have directly messaged and contacted them. They have they have put on their pages on the you know social media pages and stuff like that I have not heard of any response as such except for one maybe I think somebody put a message and they said we'll get back to you and but that's it no comment like that and I guess the next thing which we are considering is legal action I mean legal in the sense send them a legal note from notice from a lawyer or something like that which is definitely something we're looking into. Can you tell us a little bit about this print itself and the kind of effort that goes into these prints and so when we started about working with these about 20 years ago it was something that a couple of friends of ours Dindas collective they're called Meeta and Sunny. Meeta and Sunny through Oxfam approached us to do a range of t-shirts for young people as an effort to revive this craft as well as make young people you know realize what a fabulous craft we have and contemporize these things but with us the idea was to actually go back to the source do not to not hide the inspiration for the print right so we brainstormed and we came up on a range of designs that we'd like to do in block printing okay one of them was this yoga design because it was also like I said for us people tree at that time was a way of making young people look at Indian culture afresh to look at crafts afresh to know that they're always contemporary they're always fashionable they're always fair trade they're always environmentally more sound all the range of things that we felt that that excited us about these things right so so do you think Dior actually has gone through this degree or they've just machine there is a machine print thing there's a complete machine print yeah never going to do that client doesn't go for these things the client doesn't want some faded t-shirt the client doesn't want something that doesn't last forever I mean Dior and all of what are the what is the west want they want immortality whereas handwork is never immortal it's all organic it all will go to the earth it is it's a natural thing nothing is identical you know the west always looking for identical haja t-shirt jee jee ekdom identical leh so no work like that sorry but that doesn't stop them from taking a design and making it in a factory and do you think even as a designer it's the one is that they've stolen a pattern but also the process the complete disregard for the kind of process not that the process probably doesn't matter to them fashion does the thing is that if it had been one of the many designs and we do many I mean we're quite prolific that way we just sort of keep creating and enjoy that the thing is then it wouldn't have mattered but I think this one being so sort of what should I say so classically typical of people tree you know it's such a essentially known among people as a people tree print it really became a symbol of kind of symbol of a protest in a sense of these big big brands following smaller enterprises in this kind completely you know ridiculous way all right thank you so much go free thanks so that's all we have time for today at news click let's hope that international brands are a little more conscious when they think about copying blatantly copying designs from independent designers who seem to put in a lot of effort into making these designs thank you that's all today at news click


This week's IonMPI is from Kemet. Lady Aida, what is your pick from did you key this week for IonMPI? I'm glad you asked. We got this. This is a series of sensors from Kemet. They are the TRS series of thermostat sensors and what's neat is I actually learned a lot writing this IonMPI because I didn't I misunderstood how they worked. I'm going to explain to you how these sensors work. So these are sensors that basically they're in like every appliance you know and essentially they're a switch that when you hit a certain temperature they either open or close. So let's say you have a heater blanket or something.  So there's a thermostat but maybe there's also a safety interlock you know if the heater blanket gets too hot the connection opens your heater blanket no longer gets electronics electricity through it and it turns off. You know likewise you could have an alarm in your freezer the temperature goes below or above a certain point it's you know either gets too cold or too hot and alarm goes off and you're notified and that could be done with this very simple switch no firmware coding required. So there's the thermal read switch series so it comes in a couple different packages and we'll show you this and there's multiple different ranges so each one has a set point that either make or break below or above that point. So the make ones you know when they go above the temperature they make the connection the break ones when they go above the temperature they break them whichever make above make above break break and they come in different sizes and shapes with wires or not or you can solder them onto things. I got a couple that were solderable and this is interesting so you know I was actually I thought that these kind of worked like PTC fuses which we had talked about a few you know weeks or months ago we covered a couple PTC fuses where the material as it gets hotter the resistance changes but actually these use the curie point like the scientific the theory of the curie point which I remember from like high school and college so this is a really neat thing basically we have some magnetic materials and you know you have all the spins going in one direction and that's what makes you know there'd be a north and a south pole to the material but then you know sometimes you know sometimes you hit a material it'll scatter the crystal or if you get it above a certain temperature and what's interesting is it resets like if you you heat it up to a certain temperature and then the crystal kind of breaks apart you no longer have this magnetic property it doesn't act like a magnet and then when you go back down it reforms into the crystalline shape and the magnet the magnetic property reappears so what these sensors do is they have a special material that the thermo thermo right which is tuned by Kemet to have that effect the curie point at like 15 degrees C intervals so it's like 40 55 65 75 whatever and you can see in the graph they have in the different points and they take a really hard stop like when it hits that point it really does like turn from a magnet to a non-magnetic property almost instantly so inside all of these sensors is basically a reed switch which a lot of folks here have probably used before this is a generic reed switch that did your key stocks and the reed switch has two metal plates and usually and there's they're in a glass case or you know some other case that's totally got in inert gases there's nothing inside there's no oxidation that you have to worry about and when a magnet comes close the magnet causes the two pieces of metal to touch to make the connection or separate to release the connection and so we've used these for like door and window sensors you know when when the magnet comes close it closes the connection an alarm goes off or vice versa but with a little bit of clever hacking you can turn these into temperature sensors so this is basically how like a reed switch works normally in the top right there you've got a you know a magnet and it comes close and the two pieces of metal touch each other and there's a a magnetic field on the left side I mean this diagram is from the data sheet this is good but I actually like let's get we'll skip ahead because I'll show the very nice diagrams so there's two types and basically they do like a thing where the outer ring is that thermo right that material should get is a magnet until the the temperature rises a certain point and then becomes demagnetized and for the brake type the the thermo right's in the middle and there's permanent on the outside and on the make type the thermo right's in the center and then there's a little bit of a spacer and I'll show you the video also because it's kind of interesting how this hack but in the center is a normal reed switch okay so for the brake type I thought this was we know both they're both kind of simple to well simple but they're easy to understand so there's the reed switch on the inside and see there's on the center there's the pink thing which is which is a cutaway of the ring and at the low temperature the middle part is magnetic and so the two permanent magnets on each side there's a continuous field that's not broken and so it the reed switch is closed and then when it gets very hot that center part again becomes a magnetic the pink part basically acts like a open connection and there's no transference of the magnetic field through the material anymore the magnets no longer right next to the magnetic field is no longer right next to the the two reed switch leaves and they open up and now the switch is off and then when the temperature goes back goes back down it remagnetizes the field flows again and vice versa so like no power is required no sensing no code it just magically happens at the curie point um likewise the make type uh is sort of similar except there's you know there's two thermo right rings in the middle and the magnet and basically the same thing where it's like you want to create or remove the magnetic field which would connect or disconnect um the reed whichever whichever way you want I mean usually people have a brake switch because your toaster oven it gets too hot you want the electronic the electricity to disconnect and these come in multiple different shapes there's also the ohd family which is like sealed and comes in like this epoxied enclosure and that's uh for u l csa or tv rating um there's you are waiting for looks like one of the lead terminal ones but these you know you can use for anything again they're very simple they just kind of work um physics seems to have not let us down yet uh so far and so you can rely you know you can rely on this knowing that there's not going to be any like funky weird you know watchdog timer that has to go off or like oh what if you know the the ptc thermistor isn't like you know it has some leakage current like this opens a reed switch it's open it's open like it's there's no electricity passing through um there's just some things that you know they they show what they're they're used for you know refrigerators and rice cookers and uh water and whatever you know there's there's basically two use cases I think of that are really good one is as your main control like I mean these these could work as a great sensor input into a more advanced microcontroller um you know definitely you don't have to you can just have a switch and it would uh activate an interrupt or or what have you just you just know whether it's above or below the temperature but it's also great as an interlock you know you have a more complicated feedback system but then like if that feedback system fails for some reason you have something like that protector element it's like no matter what it will never get above this temperature because if it did uh the electrical the electrical connection would open and if you're not sure which one you want there's also a kit that uh did you keep it together with kemet that has like kind of one of each make and break and various temperature uh trip points the curie points uh so you can pick up this kit if you just like want one of each if you don't know whether you want make or break type or what the temperature rating is um and these are the parts that are in that kit so you get like you know from 50 degrees up to 120 degrees half make half break all of them can pass um 100 volt ac and uh looks like about 0.3 amps um so good for a signal or even low power available did you key and because we're showing this it means it's in stock it is in stock um i got a couple of them but there's um there's like every rating is available you know it's like i actually really like stuff like this because i feel like you know i spend so much of my time in like firmware and like firmware is great but like i would never trust it with my life um with my safety whereas i would trust something like this it's like it's the curie point it's physics like it's reliable i i believe in physics yeah all right and we have a little bit of a video that has some of uh information about they haven't very nice it's much longer but we have a little snippet yeah let's shift our focus to the operation principle of the thermo sensor simply put it is a thermal switch that opens and closes the contacts within its built-in read switch by the shift in magnetic energy of thermo right and permanent magnet here a ring shaped thermo right is in the sensor sandwiched by two ring shaped permanent magnets with polarity arrangement as shown with a read switch fixed inside the rings when the temperature of the thermal right is at or below its curie temperature it functions as a magnetic body in contrast when the temperature exceeds the curie temperature it becomes a non-magnetic body this change in the characteristics shifts the magnetic circuit which makes or breaks the contact in the read switch the thermal sensor has two types of switching action break type and make type the break types mode is normally on that is turned off at the operating temperature as opposed to make type which has a mode that shifts from off to on


For the Circuit Python Parsec today, I wanted to show you how you can play a wave file on the Circuit Playground Express or the Circuit Playground Blue Fruit inside of the Circuit Playground Library, which gives us these really high-level commands that are very consistent and easy to use. So in this case you can see I've got a library and importing. That's the Adafruit Circuit Playground Library importing it as CP. And then the first thing I do is I play a wave file with this simple command cp.playfile and then the name of a wave file that's sitting on the flash storage of the device. So that's what happens when this starts up and I'll demonstrate that in a second. Then in the main loop of the program I am checking for button presses and a switch to be thrown. So you can see here if CP button A that's the button on the left gets pressed then depending on the state of the little toggle switch we play either this one file BP box wave or this other one triode drama wave. And the B button always just plays this desk up dot wave.  I'm just going to press reset and you can hear it do a little sort of Game Boy startup sound. And now I'm going to press the A button. I got a little file there called BP box. Now I'm going to switch the switch to the right and when I press the same button I'm playing this other wave file triode drama. And then the B button here always plays that one little bleepy file. And that is how you can play wave files right on the Circuit Playground Express or Circuit Playground Blue Fruit inside of Circuit Python using the Circuit Playground Libraries play file command. And that is your Circuit Python Parsec.


How to handle unfriendly relationships between students It is inevitable that not all students in every class will get along Unfriendly relationships can develop in the classroom, but they may also develop outside the class or even exist prior to entering the EFL classroom In any case, our first priority as teachers should be to improve the relationship between the two or more students who do not get along However, if the antagonism runs deeper or becomes too disruptive to the class, it may be better to separate the students so that their dislike of each other does not bring down the atmosphere of the entire class.Engaging activities for enemies One way to facilitate the improved relationship between two students could be to have them do pair worker group work that is necessarily cooperative It would be especially beneficial if this pair work involves sharing information about themselves so that, hopefully, the two students can not only connect through the common aim of completing some task but also learn to better understand each other One activity to force cooperation with a common aim could be to group the students to complete a task where each student only gets part of the story and they must then share information to figure out the full story It could also be beneficial to pair them up for a pair share activity where each student must ask the other student some questions about him herself and then report the information about their partner to the class Some form of accountability, in terms of a completed activity or report to the class, will be necessary to ensure that the students actually work together instead of ignoring each other and failing to complete the activity or attempting to complete the activity individually when it is meant to be done as a group However, if done correctly, this will make sure that the students interact in a productive manner, which will hopefully increase their respect for each other in the context of the class Speak individually If this manner of improving their relationship doesn't work, it might be beneficial depending on the age of the students and whether or not this can be done without making it obvious to the rest of the class to speak to each of them individually and find out what the source of the antagonism is Again depending on the previously mentioned factors, it might then be helpful to mediate a discussion between them so that they can clear up their issues or ask someone with a better grasp of the native language to do so since this would be a situation when being able to express exactly what they meant would be especially important This could be effective regardless of whether the antagonism developed in or out of the classroom, but it must be done carefully so as not to make the antagonism public to the class The morale of a larger group However, especially with younger students and especially if the antagonism is related to some issue outside of class, it may not be possible to get the students to interact in a civil manner If two or more students have a public antagonism, it can affect the morale of a larger group or even the whole class Rather than forcing two students who continually do not get along to interact, it might be best in these instances to separate them to ensure that the class as a whole can maintain a non-hostile environment This can be done by rearranging seating or ensuring that, in group activities, they do not end up paired together It is important in these instances to not make it public that you are separating them because that will likely only embarrass the students and make existing hostilities worse Are you ready to teach English abroad? Take a TEFL course to become certified The goal is, as much as possible, to allow the students to sort out their own problems as this is less likely to embarrass them and more likely to produce a lasting result If it is necessary to step in more directly, then we must again be careful not to embarrass the students in front of the rest of the class by singling them out or making their problems public Speak with an ITTT advisor today to put together your personal plan for teaching English abroad Send us an email or call us toll free at 1-800-490-0531 to speak with an ITTT advisor today


As important as taking the mock is to assess your performance and to see how you've actually done and what are the areas you can improve and assess yourself on these four parameters. 1. The content. Listen to what you're saying, the words that you're using and assess the content of your answers. 2. Parameter. Fluency. How was your speech? How did you communicate in the mock interview? 3. Pace of speaking. How was your pace of speaking? Your pace of speaking has to be somewhere in the middle, not too fast that the visa officer misses it and obviously not too slow that you're not even able to finish what you have prepared. And lastly, but most important, eye contact and confidence. The USA visa process is a completely interview and interaction based process, documents are very rarely asked. So how you present yourself, how you maintain the eye contact and interact with the visa officer is a big part of the game. And this is going to give you an assessment of how you have performed and what are the areas you need to improve on.