So this month's topic as we covered last week is compelling conversations and we wanted to kick off this episode where we're gonna be diving into a fun article or a listicle here around how to connect with people and really define what we mean by compelling conversations. What does that mean to you, Johnny? Well it's first of all we want to get the doors open and we've been talking about that and I think if it goes back to the first impressions episode with a great first impression gives you a wide window of opportunity and then we had talked about getting things started and now showing some interest letting them know that you're curious about them you're getting the conversation and I think this is the opposite of small talk yeah right when people think about conversations and and getting nervous about what to say and what not to say a compelling conversation stands out it makes you memorable and it opens the door to connection that's what we mean by compelling I know a lot of times we overestimate what that means and there's fireworks in our head and it means saying the perfect things at the right time that's not what we're talking about here it's a window to vulnerability and connection. Well it's an easy it's easy to think that it's always easy to think about oh this is where the magic is going to happen but that magic is all the work that happens before, during and after that allows that to stick and so many people say if you see compelling conversations easy to go oh this is the episode where they're going to drop the secret of the memorable amazing story that everyone should learn and everyone should pull out the rabbit out of the hat and it's not as sexy as that however it can be a lot of fun if you understand the working components from the non-verbals and the verbals and allowing another person to share yes a lot of times we think compelling conversations we think of our own pitch and what we are saying and how polished it has to be and how impressive it has to be it's actually the opposite of that and that's why we love this article. Well think about it if if you're putting all the pressure on yourself to make this the magic happen what we usually see especially when we're doing video work and it's easy to get caught up in this where you're just steam rolling and plowing over the other person because you have this thing that you've worked out you're ready to roll you know it works magic it's worked that one time in the past and so every conversation goes this comes out at some point and of course the other person how the only thing that they're gonna remember the only thing compelling about this is how to get out of it right and where does this person even care what I have to think about this and when we talk about conversations it's it's a two-way street. Absolutely and now we're adding some depth it's not that surface how's the weather or what I like to do on my weekends or what I do for work we're taking it a level deeper and today's article is eight insanely effective ways to connect with anyone you meet it's by Dr. Kerry Petsinger on Life hack we'll link it up in the show notes if you have questions around compelling conversations how to be more engaging how to be more memorable submit those for us to answer on the last episode of this month in our Q&A episode you can submit those to me AJ at the Art of Charm or on our social media channels at the Art of Charm on Instagram and Twitter we're happy to answer your questions on how to be more compelling but what's really interesting about all this is we're talking about how to get to connection and I feel that a lot of us struggle with that because as Johnny was saying earlier we have this script in our head of how it's supposed to go and we want to tee things up to the best of our ability when in actuality this is more of an art form this is more of a dance in the conversation than blasting other person with information well I think there's also some some toxic movie ideas of what it looks like as well you know you might see the movie where the guy is really slick and he has he has this great story and she the other person is looking to marveled in this and the in the story that's been created and he's laying out there and so we have it in our head that we need to have that happen and you know that would be great but it's never just on us it's a conversation to a street there's two people participating and another misconception that we hear a lot is opposites attract we were just talking about this earlier a lot of people look at me and Johnny as opposites on the surface level but in actuality we haven't seen that in our lives opposites don't attract and stick together opposites actually lose interest very quickly because what's going on below the surface is actually the more important stuff and what do we mean by that Johnny values trades ethics all the things that you care about most is what where the the attraction in this in the stick is going to be and you know everyone can have their outside example right of of oh here's two opposite people yeah but if you look below you're gonna find all the things that link them yeah and those those beliefs world views morals ethics are what have joined for me and Johnny and created that connection it was not based on our music preferences it's certainly not based on our sports team preferences but it's easy to get caught up in that surface level stuff like oh you know he's in the rock music so am I we like the same genre oh we're gonna connect we're gonna be friends it actually happens much deeper well you know it's funny as you mentioned it's but it's because it's I think it's conversations that you and I would have with music or sports teams that are a lot of fun because there's so much disagreement there with all the other things that we do agree upon so we're able to have these colorful conversations that you know I think that's what makes our conversation so compelling to others who who listen to the show or who marvel at the conversations that we'll have on perhaps on the masterminds or dinner we're dinners when we're doing networking stuff as they see us kind of maybe it can look to the untrained eye that we're squabbling right oh really not there's a lot of give and take back and forth and then throwing in the shots but it's I mean it's but it's all the other things that link us behind all that that makes those conversations so colorful and fun and we can throw shots at each other and not take it personally I think we also respect competition true right and I think sports are one of those ways that it bubbles to the surface but you don't have to be into sports to enjoy competition I mean with the rise of e gaming and and video games in general there are plenty of other ways than sports to compete with one another but our respective competition creates this colorful banter these opportunities to push back and forth and sometimes it can be a little jarring to the outsider of like oh AJ's digging into Johnny or vice versa with all of that the connection for us going back to those worldviews and mindsets of growth and being into personal development those are things that are happening below the surface that a lot of us aren't asking the right questions to bubble up to the top and I think that's why when we hear opposites attract and oh it's all based on commonalities and similar interests it's much deeper than that so how do we start getting that connection how do we actually get to that point well the first point of the article here is pay attention and I know we've talked about this a lot on the show when it comes to value it's one of the easiest ways we can give someone value is to give them our attention well to go back to an episode was it 694 694 becoming high value and when we talk about value those three a's attention approval and acceptance go a long way in allowing people to feel good and if you want to have a better idea of how that works I would go back and listen to that that episode because it will it will allow you to understand how important paying attention is and why it is so effective in compelling conversations and listen in today's world it's hard to pay attention there are so many distractions we've joked about it before it's the attention economy you have businesses fighting for your attention marketers fighting for your attention friends family members co-workers all fighting for your attention and when you give someone your attention it's meaningful it allows the other person to feel fully committed to the interaction well ask Google how important your attention is well they actually have a number billions of dollars absolutely and so if they find it that important if Facebook finds it that important if Instagram finds it that important then your friends family and the people around you your social circle they should find it that important they should value it just as much as those tech companies and that's why they allow you to give those token moments of attention I like this I'll comment here I'll interact there it's all what they're doing is they're using our attention and they're monetizing it for their gain but it is important and we all seek it as humans and there are a ton of studies that demonstrate that active listening is one of the most crucial skills in conversation though it can be difficult I think once you get the hang of it and it's something that you bring a conscious effort towards you can become really good at active listening and you can it can redefine how you look at conversations and but just by being present I know for fact of when I walk into the podcast studio to do these episodes I cannot be looking at my phone at least I tried to not to a half an hour before we come in here because I have to re-get my brain to get to get present because if not I'm gonna be thinking of did I get another like on my last post like how is that going to help me what's going on in here and I'll be honest I still struggle with this it's not it's a skill that you're gonna work on your entire life because technology is fighting very hard for our attention and that's a battle so I don't always win the battle I lose the battle sometimes I have my phone I'm flipping through things and bouncing between Slack and Instagram and email and trying to keep up with everything going on in the business and answer the fans but when we can unplug from that which is why we do it on our mastermind events we grab everyone's phone we grab everyone's phone in bootcamp when you can set your phone down and give a stranger your attention well that starts that compelling conversation that allows the other person to feel valued and let's go through some simple studies that back all this up right we got a study here from Harry Wigger at the University of Central Florida active listening is more important in making people like you and making them feel understood than giving out well-meant advice or simple acknowledgement like I hear you I mean I hear you is probably one of the most frustrating responses to get in conversation especially if you're being vulnerable I love it when people are on their phone like yeah I hear you know you're not hearing anything in fact saying I hear you is pretty much a universal signal you didn't catch anything it's a simple dismissal and you can add I feel you bro you can throw that one in there as well it's as good as cool story bro in my book I hear you well you know it's it's a wonderful thing to know that just being present is going to go a long way because now you don't have to roll into the your mental Rolodex to try to figure out how you're gonna counter what's happening you being present giving that person your attention is is plenty and it's easier than we think as Johnny said it's so easy for us to go cerebral go straight to what am I gonna say next or how does this link to this story or or where have I heard that before or how can I connect on this it's simpler than that it's actually giving the other person a moment completely to speak their mind and allowing yourself to hear everything they're saying now paraphrasing and perception checking is another essential verbal skill paraphrasing means repeating what the other person has said in your own words and that gives the other person an opportunity to one realize that you heard them yes and to an opportunity for further discussion they could either agree with your perspective on what you just heard or they could disagree with it but that disclosure is how we start the ball rolling and start get compelling well one of the things that I've learned and I this this gives the value because I don't not only that it shows that that you want to make sure that what you heard is correct and I love using the phrase listen I'm going to repeat back to you what you said just so I'm clear and if I am not please correct me right and that goes a long way it shows the care it shows the attention there's also they're approving there and in the conversation and what's being said so that we can move forward there that's a lot and it's the beginning of empathy yes it's the first step on that empathy train now perception checking means telling the other person of your perception of what's going on and giving them a chance to agree or disagree so paraphrasing is recapping what was said perception is now what your thoughts and feelings are about what's going on do you have you noticed in what we've just talked about right there and none of that happens in twitter or facebook paraphrasing have you ever seen let me let me make sure I've got your post right because I'm before I blast you I was at 240 characters now yeah oh my god yeah there is none of that it's what and what's even look at us perception and paraphrasing half the time the arguments on facebook is from an article title that is for clickbait that no one has even read you just want to go off let's talk about how often have you clicked on those titles and been frustrated that your question wasn't answered every day at least five times so they're the good attention's being sucked yeah so paraphrasing and perception checking essential verbal ways to showcase to someone we're present let's talk about some non-verbal ways to showcase we're present eye contact yes when they're talking so this is not at the start of the interaction now we we've moved from hey that small talk to all right now we're getting compelling we're asking the other person to be vulnerable so giving them our attention with some eye contact is important nodding along a slight head bob so that people know that it's registering is a simple way to let them know you're present well and you know it's so funny I've I've seen and have been in so many conversations where the other person is just emotionless and it's and I you know a lot of times to point that out they don't even know that their stone emotionless face uh and it's you we use to contribute that to some processing right we call processing face they're in their head they're trying to they're they're giving you a lot of attention they're they're going through what you're saying in their mind but because their face is emotionless uh you don't really know if you're getting through if they even care what you're even saying and listen we do it with young children we are emotive we showcase emotion because we realize they might not be catching everything we're saying verbally so it's important to showcase that positive emotional presence same thing with strangers we're meeting for the first time if you're stoic if you're just not emotive at all well the other person can read that in a very negative way oh I'm not interested in what you have to say I'm not engaged I could care less so allowing the head nod the eye contact and some emotion to show on your face is huge and then open body language and how often do we see this Johnny where people will cross their arms make themselves smaller close off that body language from the other person well it's such a simple thing to William James and I talk about this all the time William James like it was like late 1870s puts posts of paper you know how you move affects the way you think and feel now if you're going to publish that science is going to take you to task okay well that's a nice idea that's nice hypothesis we'll actually test that and through you know 100 years of testing these ideas and these theories not only did science come to the conclusion that William James was correct but they also had the data and science to point out that how you move affects the way you think and feel and your brain will produce the chemicals to back up those thoughts and feelings so ideas such as fake it to you make it or act as if which I think we'll be talking about in a minute here go a long way and this is when we come back to it's easier to act your way into thinking than to think your way into acting all the quick wins in self development if you want to start feeling better about things and gaining some control come through body language and then once you can get that corrected and start getting some wins and start feeling good then you can go to the head and start working on all the much more difficult things and all the circular thinking the flawed thinking cognitive distortions a lot of those types of ideas that are going to need your body language to help break through some of those circular thinking and allowing the other person to feel that attention through your nonverbal communication is important we all notice the universal signals of disinterest so if we can start to showcase more active interest in our body language will the other person is going to feel more comfortable opening up and moving to that compelling conversation yeah I think every guy who's listening this knows the signs of disinterest really really well we've seen him a few times before out there taking some shots for sure yeah it's so funny it's like we've seen him so much we start looking for them even when they're not there which once again this is why I was talking about breaking that circular thinking because you you will see what you're looking for whether it's there or not and science does show that we are terrible at active listening oh yes there's a study from Dick Lee at the University of Missouri who said basically you can think faster than someone else can speak so most of us speak at a rate of 125 words per minute while we have a mental capacity of 400 words a minute so we're going to be filling in the other 275 with our own words very often our own words can muck up our ability to be attentive to be present well it goes back to the lens in which you view the world and and what has colored that lens from either rose colored to crap colored so any other thing you know it's funny that you mention this because one of the things that I had spent my time on on our break while I was in Portugal both of us had an opportunity to go do some traveling and and for myself this was the first time that I was going to be alone for a while and I wanted to use it to my to my advantage and do something I've never done before so having a journal and journaling the stream of consciousness and then and then diving into some of the fleshing some of those thoughts out that I found more interested more interesting and it's funny because yes I can think or speak 125 words per minute but when you're writing out all your thoughts and then fleshing them out it is it's interesting to know those 400 words that are going on when you're starting to write them yeah it doesn't come out that fast and you start to realize the all the the would you say 275 that you're coloring in with what those are what the lens is that's those are made of and it's through being able to journal that stream of consciousness and look at it objectively and how big of an impact your emotional state has on it right I'm sure your stream of consciousness is a little different when someone cut you off in traffic or your uber driver was tossing you around in the back seat well to be able to ask yourself the question why multiple times on a thought and follow it all the way through to its root is I don't well when do we get to do that anymore like you have to actively give yourself time to you have to allow yourself time to do that I think it happened once it was a brownout that hit the east coast of the US where no one had internet or power why and then we got to the fifth why hopefully you answered it the second point made in the article is seeking feedback and and how many of us try to avoid this and try to push our own agenda and our own perfection and our own successes on other people instead of allowing other people to give us some feedback allowing other people to color in a little bit what's going on and listen we now know that we're terrible at active listening where we struggle with being attentive yes and we're listening to this podcast because we want to improve so getting some feedback on our ability to communicate is helpful well in order to do that to in order to elicit feedback you must be open to the idea that there's feedback and there's room to grow that you can improve and now if you've been listening to this podcast for any amount of time and decided to share it with some friends you might have found some pushback because all of a sudden you're handing them something about self-development and you know as as far as self-development has gained some strides in the last 10 years I it still carries a bit of a stigma what do you need to fix about yourself but if you're at anyone who wants to to get better at anything you have to be open that you can and it's starting you know we talk about the Dunning Kruger effect all the time and it's even listed in here and and it's the phenomena that people of lower intelligence tend to beat their chest about things that they don't they don't know about where the people of higher intelligence know what they don't know and can will be a bit awful yeah they'll underestimate underestimate their abilities of things they don't know because they know what they don't know and how can you get better at a thing like compelling conversations if you're not willing to accept feedback and one of the things that I and I have to credit you for this because you've definitely helped me understand feedback through our years of doing business and it is something that I look for now but it's not always welcome right it's not always you're not always excited to get it because it might not be what you want to hear however how much stronger are you again those learning moments are coming from feedback and and here's the thing when we seek advice from strangers it leads to compelling conversation it gives them an opportunity to share their opinion it allows the spotlight to go on them we're not stealing the spotlight demanding their attention and oftentimes people will give unsolicited advice they like that moment they relish that moment so if you want to start a compelling conversation with someone seek some feedback on what you're doing and allow them an opportunity to mentor you give you some advice and that's what the author saying here with going to Toastmasters going to improv two things that we talk a lot about with our bootcamp participants the training of getting better conversationally doesn't just stop with oh I tried it a couple times oh I worked on it for the last month and I'm good it's an ongoing thing to understand how to communicate more effectively more efficiently and engaging you need to be talking to lots of people I you know it's it's funny I think you have to find opportunities to get your ass kicked in order to accept feedback well right like improv they're not always going to be you're not always going to be the best on the day you're going to go for some stuff it's going to fall flat on your face but you're going to get better like Brazilian Jiu Jitsu BJJ basically you're going to get your to get your ass kicked and then because of that you're going to learn from it and everyone who is open to those ideas has the fast track of betterment absolutely and seeking feedback outside of in conversation but in life is probably why you're listening to the show you want to grow as an individual and outside feedback and perspective allows that to happen the third point the author makes here which dovetails nicely into our conversation formula is asking questions we talked about this on the last episode and how or how important absolutely and asking the right questions allowing the other person to talk about themselves which is their favorite topic and when we give them that opportunity going back to point number one we add some attention in there oh my god this is a killer combination you just you said it a killer combination you're showing interest you're asking questions they now have an opportunity to talk about their favorite subject and you're giving them value in doing that so you've also gave them value in the beginning of your showing interest so there's like how much value are you throwing in their direction just by allowing them to talk about themselves and that's why i love the conversation formula asking a question listening to their answer and always responding in the form of a statement illustrates that giving them an opportunity to share being attentive and listening and then disclosing something being a little vulnerable putting out your opinion sharing something with them that is a powerful way to get the conversation moving in a direction that's not boring small talk and for everyone out there who let's just and we hear this all the time i the the what we hear is i find at times i run out of things to say well that's one wrong way looking at it because it's just you running your mouth right but two there's only so many questions that you can ask to get the other person talking before it just gets weird or the conversation collapses on itself so and this is why the conversation formula is so important so that when you ask the question they give an answer and you're now you've gotten all the information you need to to tee up something that is sharing about yourself now yeah that disclosure is so often lacking when we get stuck on the question train where we just ask question after question almost stealing information from the other person until they're like this guy's not paying attention to me this guy's not doing step one now number four is also challenging i'm not going to lie if we we joke about this a lot we only have so much memory in the database to remember names so a lot of guys will ask us hey how do you remember a name if someone offers up their name i try not to go for the name until i have something memorable about their personality or something else to latch on to with that name exactly you know there was there's a fun game that the improv girls always put with erin and susan they always come in and they do this game where everyone has to make up a name but it's actions and i from the very first time i ever played that improv game i still can go around the room and remember everyone's action because it was burned into my brain and because it was so much fun right so you know if you can tie that name to as you mentioned as an action or a memorable moment it's going to go a lot easier for you repeating it as as awkward as it may sound in the beginning repeating it a few times as you get the conversation going helps quite a bit associating definitely helps we had a a wonderful tour guide in iceland we did a walking food tour we had some lamb hot dogs some amazing meat soup and her name her name was good knee yep and everyone was asking what how do you say that again and i said bad knee good knee and immediately everyone remembered her name and all the guys who are in iceland listening now can definitely remember it because we associated with something else that we knew right so sometimes these names that are a little tricky that are not usual for you good knees not a typical american name i think it's probably a typical icelandic name associating it with something else that gives you that ability to pronounce it is very helpful let me ask you this when do you feel when do you start to feel bad how many times before you forget somebody's name do you start to feel bad like if i have to ask a third time i feel like just a complete asshole i'd say three is pretty much yeah unless i've consumed a fair amount of alcohol and i have some sort of plausible deniability for such ignorance yeah three is yeah three is the max but i i try not to push for the name in the very beginning no when you're working on talking with a lot of people much and that's the here's the opportunity to make sure you're giving them your active listening so that you can find those moments that will burn a picture or a moment in your mind that you can attach a name to and dale carnegie said it best everyone's favorite sound is their own name when you are using a person's name they are going to remember you so that is a way to get that compelling conversation now number five kind of goes along with i believe number two which was getting some feedback number five here is don't pretend you know everything how many times have you been in a conversation that's uncompelling with someone just bloviating about how much they know how much they've read how many videos they've seen and how they have all the answers to your problems i thought that is that a just an la thing i don't know i'm pretty well traveled and i've felt it everywhere i've been i think it's it's one of the best things that you can do that goes with the dunning kruger effect right it's just like first of all you you should be comfortable in knowing what you don't know so that you're able to ask questions so you're able to get better so you can learn about other people rather than as you mentioned bloviating about everything under the sun just for the sake of hearing your own voice and stating to someone how much you know or trying to vocalize how intelligent you are how well read you are is always a bad look well here's the you can continue to talk about all those things that you just mentioned but the more you're doing that you're not convincing anybody no and in fact the more you're talking the it's easier for you to talk yourself out of any of those things yeah i i love this idea of a spotlight effect when i'm meeting someone i'm putting the spotlight on them they're the star they're the expert allow them to bloviate pontificate and celebrate themselves but if you come into a conversation wanting to puff your chest out wanting to talk about all these different amazing things that you've done or you've seen or you've read you're actually going to lose the other person's interest and that is not a compelling conversation and we never connect on people's perfections it just doesn't happen so we always connect through the rougher parts those vulnerabilities those things that are imperfect well it's it says a lot about the person you're speaking to because you know what they're made of so then you can lean in on them a bit and understanding that will be puff our chest up and we try to go for i'm mr perfect no one else is going to feel comfortable in that setting when you are willing to share your imperfections you're saying it's okay to be imperfect everyone feels more comfortable in that setting well when i hear those those stories of messing up or learning all that says to me is that person is willing to put themselves in those situations that takes courage that's not easy it takes courage and if they're willing to tell you how they failed in that situation then you also know that they've gotten through it that they were able to learn from it if all they're speaking about is the triumph then was there any did they get anything out of it it's unrelatable i don't know where this popped into my head but i've been saying it so much lately you have to be able to get yourself in trouble in order to find your way out that's just the truth of it well we've we've had a lot of people who don't know how to find their way out of trouble no no inexperience will lead you to that predicament number six here care about others nothing else matters if you don't act like you care about those around you i mean being careless does not make you compelling being careless forgetful and not again going back to point one attentive is a turnoff to people it's not going to be memorable in a good way well one of my favorite things about that is in order for you to to build and maintain a social circle that is going to support and encourage your attempt at being your best you're gonna have to learn how to care about others for them to care about you and and put you in that situation we all know that we cannot achieve the everything that we want including being our best selves without the help of caring others we are built on community and if if we can't showcase that we care about other people we're gonna be isolated we're gonna be lonely and understanding that we don't need grand gestures here but giving people a thank you when they've done you a favor when they've helped you in conversation giving people some gratitude allowing people around you to feel that you are considerate is important and it allows other people to be compelled to talk to you more to feel connected to you and we all love being appreciated every single one of us loves being appreciated which is why it's the second part of value going back to episode 694 I know we've used value a lot in this episode if you are wondering what we mean by value that's a deeper dive but attention appreciation hand in hand and giving someone value well I know there's lots of things that I wouldn't have done if it wasn't egged on by someone in my social circle I right now I'm in the middle of training for a half marathon that I had no plans on taking on till you I'm sorry however it was it was an easy pitch right you're like it's the 28th of October and I'm like wow well my birthday is the 29th I'm 45 yeah it's a big one it's a big it's a notable one I'm in and you know it's funny because I remember this morning when we were getting with our trainer getting our asses handed to us I was like cursing this whole idea of half marathon yeah we've entered the conditioning phase yes and we actually we we posted up to the family that it's happening so now we have all of the accountability remember our accountability episode absolutely identifying the goal sharing it with others and now we have a bunch of people joining us here in LA on the half marathon we'll post a link under this in the show notes under this episode for you to check out the rock and roll marathon in LA if any of you show listeners want to join us on a half marathon and compete against your favorite show host you can check it out below you know it was part of that you know I don't like I keep thinking just how amazing that beer is going to taste after that it's going to be the best beer ever I mean for all the work of months and the sweat and the tears and the blood and the I'm still trying to figure out how I'm crossing the finish line so you're already you're dancing in the end zone I'm trying to figure out how I'm going to get there but I'm starting my training and and getting my miles logged well another thing about this rate why did I get involved well you mentioned it was something that you wanted to do right and so of course I want to see you do things that you want to do I want to see you test and and put yourself out and that's in the uncomfortable situation and of course you know I look for those opportunities as well I know some of you guys have mentioned David Goggins when in your letters to us and we are looking to get them on the show I think we got made we're making what happened you know and it was something when I see his post I get fired up there's like there's between him and Jocka there's so many times where I'll wake up in the morning and I'm like I don't feel it right and I see like David Goggins flipping a tire for like a mile and I'm like all right I'm getting up yeah time to do something that I hate but here again another opportunity to bond and cement our relationship even further of putting ourselves both out there uncomfortable place yeah neither one of us are runners no no and uh but it's you know as much as I was cursing your name this morning it's gonna be it's gonna be fun it the whole thing's been fun so far we've just got started yeah I mean this this whole year has been built around change for us and improving our health is a big part of dealing with a lot of the stress that comes along with change and as I was sitting there in Barry's logging another three miles in class in the treadmill I was like all right I guess I run now so what can I do to kick it up a lot of course and when we first moved to LA nine years ago now we did a 5k yeah and it was fun it was doable so I didn't feel like 5k is challenging enough so we kicked it up to a half marathon we'd love to have some of our fans join us here in LA for the marathon I say well if if they're interested you should write us back I'm coming we're doing it all right you could write me Johnny at the art of charm.com and AJ at the art of charm.com I would love to know if you guys want to run with us now showing appreciation is a skill set showing that you care others is a skill set and a ritual a habit that we have to build over time and it's one of the reasons that we built the challenge so we have a challenge facebook group with I believe now it's a few challenges to get you moving socially you check it out the art of charm.com challenge but one of those challenges is all around this idea of creating a habit of giving appreciation to others allowing other people around you to feel appreciated whether they're friends family co-workers or absolute strangers when you work on this habit and build out this skill set it opens a world of doors and as we can see here it also creates that space for compelling conversation well you know I don't have those studies in front of me but they've been done in a million times of how it allows you to feel better I believe there's a whole section in Adam Grant's book about appreciation give and take give and take and and and part of our ritual with the family is on Wednesdays we have appreciative Wednesdays where everyone gets to post up you know who and what they're appreciative for in that day. It's a very healthy habit to have mentally when you get focused on how can I appreciate others you stop looking internally and focusing on all of your awards and all of your issues but instead celebrate others it creates a powerful virtuous cycle that people around you start to get conditioned that you treat them well you make them feel good so I want to make AJ feel good and all of a sudden you're getting it mirrored back at you. Number seven see it as a room full of friends and I talk about this on day one how important attitude is in our confidence and when we feel like we are lacking some confidence especially socially it's easy for introverts and those of us with social anxiety to lack confidence socially well it's very easy for us to see and picture and visualize all the ways we're going to fail all the ways that people are going to find us uninteresting boring lame but science has shown that people with confidence before an event before a potential stress they see all the ways that things can go in their favor they see success they visualize success well let's talk about success socially visualizing it as a room full of friends and not strangers who are going to judge you or find you awkward but instead viewing the room as a bunch of people that are already my friends well that's a great visualization to start with. Yeah we have an eager guess as a as a as a poet in 1915 he had wrote there are no strangers here only friends you haven't met yet I've heard that saying many times and it's it's a great one but you also have to train yourself to think in that manner because certainly if you have anxiety that's one thing you're already starting from a place of fear but just in in in a natural state if you haven't put yourself in that position many times it's easy to feel judgmental because you're uncomfortable and so all of us have to come from that place when we're uncomfortable we have to then rationalize why we're uncomfortable and the easiest thing to say is well because everyone here is just funny and they're they're pretentious and they're hipsters and they're this and they're that put them in the out group that's the easiest boom now they're out there and now you can justify feeling the way you do and then but the thing that happens out of that is once you put them in the out group for your body language is usually going to exhibit that as well which only forces them in a position to mirror that back and now you have that thought reinforced and now you have those people looking at you as an out group and you're looking at them as the out group now you cannot and have a good evening with two opposing forces looking at that manner and listen instilling a new mindset is not easy this whole mindset of view it as a room full of friends can be difficult when we don't have very many friends and connections and we don't feel that people judge us properly or that we can make a good first depression and a TEDx speaker Kelly McGonigal talks about how to effectively manipulate and change your mindsets and it's really a three-step process number one is simply learning the new perspective which is what we're doing now we're listening to this new idea this new concept of view the room as it's a room full of friends instead of a room full of strangers so we learned a new perspective now we have to do it as an exercise go out there after writing down this mindset go out there and practice it pretending people are your friend already treating everyone like a friend instead of treating them like a stranger and the third thing you have to do to make this mindset stick with all of her research is you have to share it with other people how great is that it's pretty awesome it's remarkable you learn it you practice it then you share with other people and all of a sudden that new mindset sticks how empowering is it when you walk into the room and feel that everyone is already your friend well you're coming you're as you mentioned you're coming from a place of power and most importantly though when we hear something like this some of us could get rather excited I know that in the beginning of my stages of really getting into self-development I would hear mindsets like that and I would want to go out but then I then I get there then I get there and I see all the overwhelming feelings start to hit because the mindset is everyone there is my friend okay well then I should be able to talk to everybody in this room well now the expectations are just ridiculous because now I have to run the room in order for me to feel that this mindset is now taking place it is a process we have we have to go out now with this mindset with obtainable goals that allow us to slowly hit the seep in it's not going to be I listen to everyone out there I would love for these mindsets to be a light switch and some can be but most not right and this this is a tricky one when we're coming from a place of scarcity where maybe we don't have very many friends we have some acquaintances we're trying to get things moving and burn off some of that social anxiety but as Kelly pointed out for us if we learn it write it down practice it and start sharing it with others it becomes a mindset that we can adopt more easily eight the eighth and final point in our article here is connecting in person and we get this question so often I I had a you know short conversation with someone what's the best way to follow up how can I connect I want I want to lengthen this relationship we get questions about how do I get on tinder and get her more connected everyone is trying to rely on technology in places where technology do not foster actual connection well there's a reason so let's dig into that reason why are we not connecting through technology why are we connecting in person because if I connect in person then it might not go so well and then I'm going to be hurting and then there's risk it's risk I and let's just let's just go ahead and say it's not going to happen through an app the connection is not going to happen well right there's a there's a phrase for it catfishing came out of this it's so easy to create a fake persona online and hide behind it and manipulate other people but when we're doing it in person we are present we are there that is compelling no compelling conversations are happening on whatsapp or facebook messenger or in tinder you have to meet in person in order for it to be compelling it almost sounds common sense but how many of us revert to technology because it's easier oh I can pause I can send a text with an emoji it's so everyone likes to think they figured it out you haven't figured it out it's not going to happen it's it's sorry it's just science it's going to happen in person and the funny thing is have you ever had a conversation with somebody that you've never met before on tinder on facebook and then you meet them in person and you're really excited because you guys have been talking for sharing vulnerable you cover topics no one else knows and then it's just crickets and you know I'll go ahead and say I recently just had a date situation that went this way you got catfished no I did not get catfished okay but it was somebody who for just the way that it just happened we had been texting for a few months texting um social yeah you were saying you just you couldn't connect at the same time in place yeah so but there's all the pictures online she knows who what I look like I know what she looks like we've been chatting we've had great conversations there was even a couple of live phone calls and real live phone calls you were using your phone well video conference calls or whatever they say I don't think I've ever seen you hold your phone up to your head so she was off one weekend I was off one weekend and she's like hey you know I'm off I was looking for something to do how about if I come out and visit I'm like all right yeah and it wasn't it wasn't like we were moving towards a romantic thing anyway we're just all just friends we're just talking we're just bullshitting but she hey she wants to come hang out that's right I was off and we made some plans and she drove out and I remember I checked in yeah because I told you I don't know if I'm going to be at work this weekend I got this girl coming in and all this and uh and you're like all right and I was like yeah we'll see what happens you know and uh and of course I was excited and for whatever reason the conversations were flat and she had the gall I know this was seriously offensive to Johnny there she goes why do you work out so much now and I was like and she's like I could never do that and I was like will we start how are we even starting off this this get together weekend with a comment and a conversation like that yeah I think the the question gives you an opportunity to explain a little bit more of your background but then the I could never do that right has the judgment placed on it where it's like uh I'm not sure I want to answer this question it was in that moment that I was like I'm like okay so this is hour one and she's going to be here the Sunday but this is what's great about this and I you were laughing I was telling you I think it was about three hours later she goes so yeah if I might get a call and I might have to go back for work and I was like she's looking for an exit this is great because I don't want to deal with her anymore you got my weekend back but you know and the the funny the weird thing about it is like how it the whole thing was odd to me because we had such a decent relationship online we were talking it was we talked freely we're setting pictures you know it's like it was just to me the whole thing was just weird but what I couldn't get is like first of all how could you ask me why do you work out so much and the other part about it's not like you know it's not like I am David Goggins it's not like I'm Joe Rogan I go to the gym for an hour and I'm out well also it there are less attractive things you can do than work out yeah so little little perplexed by that why do you care so much about your health uh I enjoy my time here I don't know and and let's listen that's you know it's that's probably a relatively new thing in the last five six years where I've really put in a lot of effort hey Johnny maybe opposites attract I think you should give her a second chance yeah that that that ship itself well going back to the point connecting in person is so incredibly important it gives you an opportunity to non-verbally and verbally communicate and be fully present we know that technology does not foster that presence when you're sending that text you got your facebook tab open you're clicking through your inbox you're not present you're not really caring and emojis can only get you so far even if you're an emoji ninja yeah it can only get you so far so connecting in person is where that compelling conversation happens now we hit you with eight points around how to be more connected and compelling in conversation but we want to add some perspective we got this great article that recently came out in the Atlantic how to make friends according to science and I think the reason I like this article so much is it it should take some of the pressure off and we we started talking about this at the start of the show you know everyone in their mind when they hear compelling conversation they have that Hollywood movie scene teed up where they met each other they had an amazing conversation right out of the gate and then they instantly were attracted instantly were connected science shows it takes a number of hours to be a quote unquote real friend to someone it is not easy to move from the acquaintance into the friend into the confidant category we're talking hours and hours and hours here but what science also says is don't give up on those acquaintances yeah those acquaintances are the first step to friendship so what I love about this article is we don't have to hit a home run in every conversation build acquaintances start getting more opportunities in the mix and all of a sudden you're going to create a space for that compelling conversation that can move the acquaintance to a friend well I think we've talked about this in many other episodes when you have a lot of options the pressure that dissipates and you don't have to put it on that one situation if you're if you're not somebody who goes out and has a lot of acquaintances then the one time that you do get to meet somebody and especially if it's somebody that you're romantically interested in you have all the pressure to yes make it work to have this amazing conversation to hit the home run right out of the park and unfortunately that's just not realistic and here's the best part interacting with people whom you have a weak tie with a weak social tie has a meaningful influence on your well-being on your mental health so even if you don't have deep friends you don't have a wolf pack you don't have that deep connection yet you're struggling with compelling conversations working on acquaintances can impact your well-being can give you that positive emotional state and environment so that you don't feel loneliness you don't feel depressed so building acquaintances first is scientifically proven to help your mental health well once again it goes against all the technology in a rapid hey i want this click this and i got it where we have to allow nature to do its job and unfortunately we can't just pay for it or click a button to allow that to happen time needs to do time and here's the thing reviving dormant social ties we just hit you with a bunch of knowledge over the last two weeks about compelling conversations hit up those people that you fell out of touch with that maybe you had a weak tie you had a connection that was fleeting reach back out to them reviving those dormant social ties can be especially rewarding reconnecting with friends as the author says here can quickly recapture much of the trust they previously built while offering each other that dash of novelty so that all of a sudden you caught up with each other and now you can practice some of these compelling conversation skills you learned over the last two weeks reaching out to people developing acquaintances everywhere you go gives you more opportunity to build those deeper relationships and ultimately i know it's easy on social media to see other people with all of these friends all of these oh god close friends in their community science shows that realistically we can only maintain five close friends i know the tv shows like to make you believe you need 30 40 friends to be a well-rounded human you focus on getting some acquaintances and moving them through two real friends and you focus on making sure that you're present for the people that you care the most about that's a winning combination you know i was just doing a facebook live for um i think it was on the challenge yeah actually which you alluded to earlier we'll drop the link and i was surprised uh how many young people get so wrapped up in that number that you had just mentioned because you know it is it it seems to be moving uh well at least it moves things in social media but that's just but that's virtually that's a virtual reality that's not real life and someone was mentioning about you know how long did it take me to build a social circle that i felt good about and it's like well social circles are fluid there's going to be people in and out of your life and your top eight especially if you're growing you're moving you got things going on people get married people's careers take off life happens and that's fine you have to allow for that to happen for yourself and everyone else but the main thing is what i told that person let's don't think about how long it's going to take let's just focus on one you get one good person in your life that everything else falls in the place and that's all it takes and once you have one good friend that you can do a lot of things with and grow with i mean the rest is easy and all of those friendships started as acquaintances yes remember that you don't need to beat yourself up if all you have right now is some surface weak social ties those are still the seedlings that create those lasting bonds and friendship and here's the thing if you're struggling even with that getting just some acquaintances start with some self disclosure the article wraps up with self disclosure makes us more likeable and as a bonus we're more inclined to like those who we've buried who we've bared our soul to so not only does it give you a little boost of confidence and creates a window of opportunity for that compelling conversation self disclosure also naturally makes you like the people you disclose to more so if you're finding yourself in a negative rut where you're judgmental you're being a jerk to people you're writing people off start by self-disclosing a little bit being a little more vulnerable scientifically you'll be more open to that connection love that


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Welcome back. In this lecture, we will have this lecture for about an hour. This lecture will be about special devices and also diode circuits. Last week, Professor Shama talked about p-n junction in other details. There are a variety of diodes, which are used in all kinds of applications. We look at a few of them. Now, we know that when you reverse bias a p-n junction, you have a depletion capacitance and this depletion region, the width of the depletion region depends on the reverse bias. Now, because of this, the capacitance C j, which is the junction capacitance of a reverse bias p-n junction, can be related to the reverse bias voltage by this equation, where C j, which is the junction capacitance is C j 0 by 1 plus V r by V 0 to the power m, where C j 0 is the value of C j for 0 voltage and V r is the reverse voltage, V 0 is built-in voltage, m is a grading coefficient. Typically, for a p-n junction diode will be the order of 0.3 to 0.5. So, when V r is equal to 0, you would get the same value. Now, this property of a p-n junction is extremely useful. There are special diodes by the name varactors, where this particular property is made use of. Now, varactors you can think of as voltage variable capacitors, where they use this variation of the capacitance as a function of the reverse voltage. The only difference is they are optimized for this particular purpose. Therefore, the grading coefficient is made between 3 to 4, so that the capacitance variation is a strong function of the reverse voltage. Now, where do we use this? We are all familiar with the fine-tuned control in our radio and such devices, portable devices. Typically, if you take a radio, the main capacitance there, the variation is from 0 to 70 pf. When you change the station, you are actually going from somewhere between say about 10 to 70 pf. Now, we all have noticed why this fine-tuned and when this fine-tuned came into picture. May be about 20 years ago, if you had a radio, it was extremely difficult to tune to short ways stations, especially at night, because the variation, the way you could choose a station at night, it was extremely difficult to choose. That is why when companies came up with this fine-tuned. In a fine-tuned, what you are essentially doing is, you are putting a varactor in parallel to the main gangue capacitor and by fine-tuned, what you are doing is, you are actually changing the reverse voltage and that can be weighted very smoothly. So, you would get variation in sub picofarad, which is impossible in the gangue capacitor. Now, so, varactors find extremely common use. So, today, you would find this in almost, not only in radios, you would find also in several function generators and all and because of this variation of the capacitance through voltage, you could use this in lots of gadgets and the variation is typically in the sub picofarad range. So, varactors you would find extremely useful in many electronic applications, especially in RF kind of applications and being a reverse bias diode, you would find that the impedance, when you put them in parallel, there is not much change, I mean, it does not affect the other capacitance much. Now, let us look at another special type of p-n junction or a diode, which is a light emitting diode. Again, today, light emitting diode is something very, very common. We find it almost everywhere, you know, mobiles, all kinds of gadgets. Today, we are very familiar. Now, two things, I am sure we would have wondered, how do we get these different colors and also what is the principle of these light emitting diodes. Now, light emitting diodes, as the word diodes say, they are also a p-n junction, they are made of p-n junction, but these are special, they are made of special semiconductors. Now, semiconductors can be classified either as direct band cap semiconductors or indirect band cap semiconductors. Now, this is based on the shape of the band cap as a function of the momentum k. Now, in a direct band cap semiconductor, the conduction band minima and the valence band maxima, they occur at the same momentum. Now, generally, we draw the conduction band and valence band at kind of straight lines, but actually, you would find them. So, what we mean is, so in a direct band cap semiconductor, the minima of the conduction band and the maxima of the valence band, they occur at the same momentum, crystal momentum. Now, therefore, what happens is, when you in a indirect band cap semiconductor, the minima of the conduction band and the maxima of the valence band, they do not occur at the same values of momentum. Typically, to give you an illustration, it would in a indirect band cap semiconductor. So, the minima of the conduction band is here and the maxima of the valence band is somewhere else. Now, in direct band cap semiconductors, we know that when you forward bias a diode, the carriers are injected, holds injected from the p region to the n region. Now, what happens is, when these carriers, these minority carriers, they recombine with the majority carriers on the other side and when they recombine, they release energy. Now, in indirect band cap semiconductors, this release energy would be in the form of lattice vibration or this is also called non-radiative recombination. But in direct band cap semiconductors, a sizable number of these recombinations result in radiative recombination or they would generate photons. Now, so this is the basic principle of an LED. Now, what I have given here, some examples of direct band cap semiconductors with their band caps in electron volt in bracket. Now, most of these direct band cap semiconductors are kind of alloys or let us say compounds. Now, gallium arsenide is a very good example. It is a binary compound. It is a direct band cap with a band cap of 1.43 and so on. Another popular one is aluminum gallium arsenide. It has both direct and indirect band cap 1.42 to 2.46. It can be varied by changing the mole fraction of aluminum arsenide and gallium arsenide. So, this is a ternary compound. You have a material called indium phosphide. Then you have gallium nitride, indium gallium arsenide and so on. There are several such direct band cap semiconductors. Now, when the radiative recombination takes place, the emitted photon energy would be equal to the difference between the higher energy states E 2 and the lower energy state E 1. Now, that can be equated by an equation E is equal to E 2 minus E 1, which will be h f or h c by lambda, where lambda would be the light emission lambda. C is the velocity of a light. Now, the peak emission wavelength lambda, we can express in a more convenient way in terms of the band cap energy by the equation lambda is equal to 1.24 divided by E g in electron volt. So, we see that just by changing the band cap, we can get different light. So, this is how you get different colors. We know that the visible spectrum is from about 400 nanometers to about 700 nanometer. At 700, we have red, 600 to 700, you have red and you have blue somewhere around 300 to 400. Now, by changing E g, you can get different values. Now, let us take an example of a material like aluminum gallium arsenide. By changing the mold fraction of aluminum arsenide and gallium arsenide, you can get different band caps. We will not go into the details of the technology. Now, this is how you could choose different materials and you could get different colors. Now, let us talk about another very special device, again a diode called a laser diode. Now, there are days when laser diodes were very costly and they were not seen. Today, it is something very common. All of us are very familiar with the pointer, which we use for presentation and it costs hardly 50 rupees. Interestingly, it is made of a laser diode, which emits light of about around 500 micro, almost 1 milli watt, a huge amount of light. Now, what is the difference between a laser diode and a light emitting diode? Both are diodes. Both emit light. What is the difference? Now, in the light emission, in a light emitting diode is by what is called a spontaneous emission. The reason why they are called spontaneous emission is because the emissions are isotropic. We said that if you forward bias a p-n junction made of a direct band cap semiconductor because of recombination, we said there will be photon generation. Now, this can happen all over the device. Therefore, it is not at one point. It is not focused. It is not coherent and the phase also is quite random. That is why it is called a spontaneous emission. So, in a LED, as you would have noticed in a LED display, you would see that the light is actually emitting from a much larger area if you look closely. In most of the LEDs, we would use as a display device and there we want the light to be as dispersive as possible. All of us are familiar with the standard LED and you would see that the structure is made such a way that light is kind of diffuse. So, there the purpose itself is to diffuse the light. Now, there is another way to get a photon emission. This is what is called stimulated emission. Now, here what is done is the downward transition, which is basically releasing of energy can be stimulated, can be triggered through another photon. Now, if you do this, the emitted photon will also be in phase and this is what is called stimulated emission. Now, if stimulated emission has to happen, then you need to satisfy a condition called population inversion, whereby what essentially what we are saying is the number of excited states on the higher energy band has to be much higher than the ground state. Now, this can be the structure, device structure of an LED and a laser diode is very different from this point of view. In an LED, you just have a simple p n junction made of direct semiconductor of the right band gap to get the desired color. Whereas, in a laser diode, you need to do something extra to make sure that you have a huge amount of carriers and also they are kind of confined to a very narrow region, so that you can satisfy population inversion. So, this is done through what is called hetero structure. Now, if you have a simple p n junction, which we are familiar with, they are called homo junction, which means they are made of the same material p n n. You can also have what are called hetero junctions, where they are made of dissimilar materials with different band gaps. Now, we will not go in the details of it. So, in a laser diode, you would make a p n junction, it is not just a p n junction, it will be a p p plus n n plus kind of structure, where you would have different band gaps and the adjoining materials will be slightly different, but they will be matched. Now, because of this, you would have a huge amount of carriers kind of trapped in a very narrow region because of the band gap difference and also interestingly, they also would have different refractive index, because of which when you forward bias this particular junction, this huge amount of carriers are generated and after a threshold value of current, you have stimulated emission. So, if we look at the characteristic of an LED and also if you look at the characteristic of a laser, they are different. Now, what we have here is the current versus light characteristic of an LED, which is almost linear. If you draw the similar characteristics for a laser diode, the difference would be in a laser diode, you would see that till a particular value of current, which is called the threshold current, the device works like a LED. So, which means it has only spontaneous emission. Once it exceeds a certain amount of threshold, which means number of carriers, it would go into stimulated emission and you get a huge amount of light. Now, the major advantage of a laser diode, which is generally written as L D is basically coherence. Now, when you talk about coherence, there are two types of coherence. One is called the spatial coherence, whereby what you mean is the light is now confined to a extremely narrow region as opposed to an LED, where we said the light is isotropic. So, it kind of emits from all over the place. Here, because of similar to emission, the light is extremely focused. Again, we are very familiar with the pointer, which we are talking about. But in a pointer, you also have a lens inside. You have another type of coherence, which is called the temporal coherence. Now, temporal coherence is the word used for the spectral purity of the light. In an LED, if you see, even though you see a light as red, if you look at the spectrum of the light, you would see that in an LED, if you plot lambda on the x axis. In an LED, you would see that the spectral width is quite large. Now, if you do the same thing in a laser diode, you would see that the laser diode spectrum is extremely sharp, meaning the light emits in an extremely narrow range of lambda. Now, this is what is called temporal coherence. Now, because of this, laser diodes are extensively used in several applications. LEDs are used in applications such as optical links, especially short range optical links. Today, we are familiar with LAN. Most of the LAN applications would use an LED, because LED is a very cheap device. The LED, which is used for LAN is not the one, which we are familiar with. They emit light in the infrared region, but the principle is very similar. Whereas, laser diodes are used in optical fiber communication. Today, in our country, optical fibers are used for communication throughout in all kind of telecommunication applications. So, that is the difference between LED and laser diode, which are very similar. Now, let us talk about another type of device, which is a photodetector. Again, photodetector is very similar to, let us say, a solar cell. The main difference in a photodetector, you would reverse bias. This is again a p-n junction, which is used in a reverse bias mode. Now, what happens in a reverse bias? When you reverse bias a p-n junction, any radiation temperature or any radiation would affect its reverse bias current. Now, that is the principle of a photodetector. In a photodetector, the junction, the reverse bias junction is exposed to light and the light energy, photon energy would be sufficient to break covalent bonds, which would result in what are called photocurrent. Now, in a photodiode, when you do not shine any light, you have a current, which is called dark current, which is essentially the reverse saturation current, as opposed to what is called a photocurrent, which is a light, which is the current, which falls due to light. Now, dark currents are typically extremely small, may be in nano amps kind of range and photocurrents can be, it depends very much on the amount of light you shine. Now, a photodetector can be thought of as a controlled current source. This is because of the reason that you have a reverse bias p-n junction, which has very high impedance. Now, because of this, you can model this more appropriately as a current source. Now, there is another very interesting device, which you can form out of an LED and a photodetector, which is called an optocoupler. Now, optocoupler is an extremely useful device, where this is nothing but a combination of LED and a photodetector. LED is essentially an electrical to optical converter, whereas a photodetector or a photodiode is an optical to electrical converter. There are situations, where you would like to pass signal from one system to another system. But unfortunately, you cannot connect a wire between these two systems, because the ground potential of these two systems may be very high and there can be damages. This is very true. If you are trying to take a signal from let us say a big vibrator or a vibrating equipment, let us say in a mechanical engineering lab, and you try to connect that signal to a PC. If you do that directly, your PC will burn immediately. In such a situation, what is done is, you would use an optocoupler where you want to connect, take the signal from the instrument without directly touching. Now, in LED, we know that would give you a light, which is proportional to the current flowing through it. So, if you apply a signal, it will give you a light, which is proportional to the signal. The photodetector, we again know, would give you a current, which is proportional to the light. So, at the output of the photodetector, you could take it may be amplified and you have a signal. It is an extremely useful device, which is used for achieving electrical isolation between two systems. There are many practical applications, where you cannot take signal from one system to another system through a wire. In such systems, you can use optocouplers. It is very easy to make an optocoupler in a lab. You need to just paste, maybe just tie together an LED and a photodetector, and you could do very interesting experiments. Now, when we talk about diode circuits, so we talked about three types of diode, special diodes. We talked about varactor diodes. We talked about LED's. We talked about laser diodes. We also talked about photodetectors. Then, we talked about an application, where you would use both photodetector and an LED, and we said it is an optocoupler. Now, diodes, we are all familiar with. The most popular and the most common use of a diode is it is used as a rectifying device. We are familiar with both half a rectifier and full wave rectifying applications. We will spend a little bit time on wave shaping circuits, which is another very major application of diodes. Now, very often, you can think of a scenario that you have a sine wave signal, and you want to get a square wave out of it. How do I do it? Now, one way is to use a comparator, maybe an op-amp and so on. You see that the moment you talk about an op-amp, you are talking about more complication, power supply and so on. This is something you can achieve easily using diodes or senor diodes. So, wave shaping circuits, I have a kind of family of circuits, where you would use the property of a diode and you would combine them with kind of your applications. Now, before we look at some simple wave shaping circuits, let us look at diode models. Now, there are different diode models exist. All of them assume diode to be an open circuit for rewards bias. Now, they all differ in the way the forward bias region is modeled. Now, we have one model, which is called the exponential model, which is a very accurate model, which essentially uses the diode equation. Now, there are two applications, where you might like to determine the diode current very accurately. For example, one such circuit is shown here. Now, if you connect a power supply and a resistor, a series resistance, connect a diode. Now, how do I find out I D and V D? Unfortunately, we can write only one equation here and there are two unknowns. I D and V D are both unknowns, but you can write only one equation here. Now, this is a scenario, where we can solve this in two ways. Either we can solve it graphically or we can solve this iteratively. Now, the exponential model would solve this either in graphical way or iteratively. Now, it is very easy to solve it iteratively and we would get very accurate results. For example, in the previous circuit, we can write an equation. We can write the equation for the current through the diode as I D is equal to I S times e to the power V D by V T, where V D is the voltage across it, the photobias voltage across it. V T is the thermal voltage and from the same circuit also, applying K V L, Kirchhoff's voltage law, we can write current V D as V B, which is the input voltage, minus diode voltage by resistance. Now, we could solve this iteratively. Let us just take an example and see how quickly we get the result. Now, initially, let us assume that the battery, which is given to you, power supply given to us has 5 volts, resistance is 1 K and I S is 10 power minus 12 amps and V T is 25 millivolt. Now, we wrote the first equation, where we wrote the equation for the diode current. From there, we can write the equation for V D, the diode voltage as V T L N I D by I S. Now, initially, you could assume V D to be 0. That would give the maximum current to the circuit. So, that current I D can be V B by R 1, which is 5 milliamps. Now, we could substitute that back into the equation for V D. So, V D will be then V T L N 5 milliamps by I S. This will give you 558.3. Now, let us see how quickly the equations converge and that shows the beauty of this method. In the second iteration, you could use this particular voltage as the diode voltage, recalculate, find I D again as V B minus V D. In this V D, substitute 0.5583 and if you do that, you get the current to be 4.44. Earlier, the current was 5 milliamps. Now, it has become 4.44. Now, you recalculate and find V D. You would get V D to be 555.4. You see how close it is to the previous result. Now, do the third iteration. Interestingly, the third iteration gives the same value, which means in just two iterations, you got the exact value. This method is quite accurate, but unfortunately, it is not very useful in a diode circuit. Because most of the time, you do not want to get this accuracy. You are interested in a reasonably accurate model, but one which makes the analysis faster. Now, this is where we have about three models. The commonly used diode models are piecewise linear model, which has fairly good accuracy and that is the model, which is used most commonly. Now, in the experiment, which we will be doing today afternoon, you would be using this. The handouts, which are given to you, gives you very detailed analysis of the circuit. Now, in the piecewise linear model, what you assume is, you assume a linear I B characteristics. We know that the I B characteristics is exponential, but here you would make an approximation. You assume it to be linear. You would see that if you choose a proper value for the resistance, the approximation, you would see that it is fairly accurate. So, you can think of here, the exponential curve is approximated by two straight lines, one which is before the threshold point with a slope 0 and the second line with a slope of 1 by r d, where r d would be the diode forward resistance. So, the piecewise linear model equations would be when I d is equal to 0, v d. So, that is the situation where v d is less than v d 0, which is the threshold voltage or the voltage which you consider beyond which you consider it to be conducting.  So, you have these two equations for these two lines. Now, for signal diodes, which you typically use in the lab, the v d 0 is typically 0.7 volts and r d would be somewhere between 10 to 20 ohms. Now, remember these values would change drastically depending on what type of diode you use. If you use a diode like IN 4001, which is a rectifier diode, you would see that this resistance value would be much smaller. The reason is IN 4001 has a rating of 1 amp and 1000 volts PIV. So, therefore, it is meant for that kind of an application. Therefore, you would see that the resistance is very small. Whereas signal diodes, which you are meant for applications up to several higher frequency, you can up to use it up to almost up to about 1 megahertz. Whereas, these IN 4001, you cannot use beyond let us say about 1 kilohertz. They have very large capacitance. So, the forward voltage, which you would get for an IN 4001 would be very different from the parameters you would get for a signal diode. Now, what we have here is a quick simulation or a quick graphical way of showing how accurate the piecewise linear model is. You see that the wide curve here gives you the diode equation assuming i s to be 10 power minus 15 amps. The other one, you have 0.7 volts as the forward drop and beyond up to 0.4, 0.7 volts, you have a line with slope 0, no current. And beyond that, you have a line with a slope 1 by r d, where your r d is 10 ohms. And you see that this particular model is fairly accurate. So, it all depends on the point you choose and also the value of the resistance you use. Now, in a lab, once you are able to get this i v characteristics, you could choose two currents. So, you could choose two currents on the y axis and find, if you expand your CRO and make a proper reading, you could get the difference in the diode voltage there. And from that, you can get a fairly good estimate of r d. That is how you would measure, if you want to model it properly, that is how you would do in the lab. Now, you have another model, which is called the constant voltage drop model. Here, you would assume that the diode is essentially an ideal diode. So, you would assume that in the forward region, once it, once it conducts, you would assume that it has a constant voltage drop of 0.7 volts and there is no series resistance. Now, this is a popular model from the point of view of analysis, because this makes analysis much simpler. If you have the previous model, which is a piecewise linear model, then it might require a few computations, whereas this is much simpler. Let us have a look at how accurate or how this particular model would compare with the actual scenario. So, if you compare the constant voltage drop model with the actual scenario, you would get something like this. So, here you see that this is a very, let us say crude approximation and still in spite of that, it is still used for the sake of convenience. You also have another model, which is called the ideal diode model, where you would assume that when the diode is forward biased, you will assume that the forward drop is 0 and the diode is also assumed to have 0 resistance. Now, this is used in circuits especially, let us say, when you talk about a rectifier circuit, you would generally ignore the diode drop. The reason, the argument there is that in a rectifier kind of application, the input voltage is much higher than this 0.6 or 0.7. So, there it is well justified. So, all these four models are used depending on the kind of application we have in mind. Let us look at, let us try to apply this particular, some of these models here. Now, what we have here is basically, we are using a ideal diode model here. We have a clipping circuit. So, essentially we are applying a 12 sin omega t as the input here. We have a 1 k series and you have a diode here, where we want to assume this diode to be ideal and you have a power supply connected in series with the diode here with 3 volt and you have the positive terminal here, negative terminal here. You have a 3 k resistance of the load. Now, how do we go about this? Now, in such a circuit, what we generally do is to see the scenario, where the diode, split that into at least two scenarios, one scenario where the diode conducts or the scenario where the diode does not conduct and then arrive at it. So, we know that the way the diode is conducted, we know that for v s positive, we know that diode cannot conduct. Now, so therefore, the output would be in this particular case would be 0.75 v s. Now, once you make v s negative, because of that we can see, we can apply k v l and we can write the currents there as i, we can apply k v l here. So, the current moving towards the node is i and i 1 and we have i 2 leaving the node here. So, we can write i as i 2 minus i 1 and you could, for when the diode is connected conducting, i would be greater than 0. From that, you could simplify and you would see that the only when diode voltage rather the input signal is less than minus 4 volts, the diode conduct. So, in summary, we would have in this particular case using the ideal voltage ideal diode model, v out will be minus 3 volt provided v s is less than minus 4 volts that is the situation when d is on and it will be 0.75 v s when v s is I am sorry here, this should be greater greater than minus 4 volts. Now, the scenario here is simulated here. So, the white waveform here is the input here and the red graph here is the output. Now, the you see here that the the the the the output will be greater than minus 4 voltage here, you can see it is a clipped and you have a flat line. If you perform this experiment in the lab, you would see that you never get such a flat line, you might get it depending on the value of resistance is used, but for most of the values you would use, you would see that you this would be a kind of you would see the small variation of the sign here. This you can get if you if you use the piecewise linear model which is given in your handout. So, if you do that you you you would be able to get a fairly accurate estimation of what you are actually going to see. Now, again synodites we have been already discussed here we will look for look at synodites on the point of view of their use in clipping circuits. Now, as we know synodites are reference voltage regulators. Now, you could use them especially there are if you want to get now if you use a synodite kind of a back to back like this and if your input is sign assume that let us have a 10 sin omega t here and we assume these to be 6 volt senors. And if you assume the diode drop the forward diode drop to be about let us say 0.6 volts then what you would get at the output would be a kind of a clipped sin wave with a a plus 6.6 and a minus 6.6. Now, in most applications this kind of a square wave would be sufficient in case we want only positive side we could just use one of them. Now, coming to another the other applications another popular application of a diode is what is called a clamping circuit. Here you would use a diode in series a diode and a capacitor in series. Now, the circuit which is shown here we have input as V m sin omega t we have a capacitor here and a diode here. Now, the way the diode is connected we know that it will permit only current to flow only in the direction from the top to bottom. Now, what will happen is as the current flows through the diode the diode that will charge the capacitor with the results that the capacitor would get charged to the maximum voltage of the input. So, in this case the input is V m sin omega t therefore, the capacitor will get charged to V m. Now, what happens is at the output side now since we have V m here with positive here negative here and the polarity of the capacitor voltage is positive this side and minus here you see that the output here would be nothing but V m sin omega t minus V m. Therefore, we would see that the output would be shifted to the maximum voltage and the output would be shifted to the negative side and another way of arguing is this way you see that the way the diode is connected here we know that this output cannot be positive. So, in one sense we can think of this circuit adjusting itself such a way that the diode charges this capacitor and the output never becoming positive. Now, clamping if you connect the diode the other way we would have a scenario where the capacitor gets charged the other in the other polarity and the waveform getting shifted up. Now, these are very useful circuits these kind of circuits are very commonly used in what are called DC restoration circuits where you could restore the DC level. There are other applications such as voltage doublers where you can use a clamping circuit and a rectifier circuit together. Now, in this case what we have here is the same circuit where we have the diode connected in this fashion. So, with the result of this circuit that the capacitor gets charged in this fashion and we said that the voltage here would be negative will be negative and what we have here is basically a rectifier half a rectifier and this will conduct only in this direction. So, the output the polarity shown here is wrong here. So, you will have minus 2 V m here. So, this circuits are very very useful especially voltage doublers circuits are used in oscilloscopes and also in television sets where you need to have very large voltages. Especially the plate voltage in a C R O or in a television requires voltage is the order of 10000. So, there voltage doublers are very useful in this circuit the moment you put a resistor you would see that the voltages slightly change and in most of the voltage doublers applications the current drawn would be very very small.  Now, rectifiers circuit if you consider a half a rectifier and if you have a load here and if the input is V m sin omega t. Now, if we did not have the resistor there then the capacitor would have if the input was this. Now, if we did not have the resistor there then the capacitor would have got charged to the full V m here. The moment we put a capacitor capacitor here the and the resistor here both charging and discharging takes place. Now, one of this is this is one of the common circuits used to get a DC voltage and one of the common misconception is the method to reduce the ripple voltage. Now, in this in this case what happens is the capacitor would charge and because of the resistor it would discharge and during the next positive half cycle it will charge and so on. Now, very often it is thought that we know that the ripple the peak to peak ripple here can be decreased by increasing the value for a given R L if we for a given R L we can decrease the ripple by increasing the capacitor. So, that is very commonly thought as a way of reducing the ripple, but one very important thing to remember thing to remember is the not only the voltage at the output, but also the diode current. Now, the diode in this particular case in the circuit shown here the diode can conduct only for a extremely short period. Now, the entire charge or the entire voltage at the entire the discharge the charge which are discharged through the resistance has to be picked up through the small interval through which it is charged charging period. Now, if you increase the value of the capacitor this time period will keep reducing the ripple will definitely decrease it will become much smaller, but the same way the the peak current would keep increasing very often there are situations where a diode may be an IN 4000 1 which is used for an application like say 100 milliamps. You all of a sudden find that the diode has packed up diode has burnt and one really wonders why it burnt and the answer is if we look at if you put a small series resistance and try to monitor the diode current we would see that the peak diode current is most of the time about at least 10 times the current that is flowing through the average the average current flowing. So, this is something which is to be kept in mind very often. So, in a power supply therefore, the solution is to reduce ripple the solution is not to put a large capacitor rather to put a some reasonable value like 1000 mF or so the solution is to use voltage regulators.  We talked about special devices we talked about varactors we talked about them being used as kind of voltage controlled kind of capacitors. We said that they are very useful in not only appliances in a radio especially in fine tune and today we would find this very often and the principle there is that of a p-n junction a reverse bias p-n junction which the capacitance changes with the reverse bias voltage. Then we talked about light emitting diodes we said that they are again p-n junctions but these p-n junctions are made of special semiconductors which are called direct band gap semiconductors and the crystalline silicon which we are familiar with silicon is not a direct semiconductor band gap semiconductor and there are materials like gallium arsenide aluminum gallium arsenide and many such materials. If you make a p-n junction out of these materials then when you pass when you forward bias this particular diode you would see that they emit light and this kind of phenomena is what is called radiative recombination and we said that in some of these semiconductors you can change the band gap by changing the mold fraction because most of them belong to like especially the ternary like aluminum gallium arsenide or even quaternary. There by changing the mold fraction you can change the band gap thereby you can change the lambda of the light emission. We also talked about laser diodes where we said the process is what is called stimulated emission where the light which is emitted is coherent both spatially and temporarily and they to achieve population inversion they use special structures which are called heterostructures which are made of different materials with slightly different band gap but matched and we said that LEDs are very commonly used even in communication especially in small LAN applications but laser diodes are the devices of choice especially in optical fiber communication and today in our country all over the country optical fibers are used as the backbone for all communication and then we talked about photo detectors which we said are nothing but p-n junctions which are reverse bias and also the junction is exposed to light and you would generally find photo detectors with kind of a quartz window and they have what are called dark current which is nothing but the reverse saturation current and also have what is called a photo current which is the current caused by light and the photo current we said is directly proportional to the light falling on it and we talked about another interesting device which we could even make it in a lab easily which is what is called an optocoupler which is made out of LED and photo detector which we said can be used to couple light sorry couple a signal from one system to another system when you talk about system we are talking about maybe major equipment maybe taking a signal from a very big equipment to a PC in some kind of scenario we cannot directly take because the grounds may be a different potential and this optocoupler is one such is a device which helps us in such a situation to achieve electrical isolation. We also talked about different diode models we talked about the exponential model which we said is a very accurate model and is very useful if you have a simple circuit and you want to find out the exact voltage and diode voltage and diode current but we said unfortunately it is not very easy to use and we talked about three more models we said the piecewise linear model where we assume a linear I V characteristics and we said this particular model is an extremely accurate model and we when we fitted this with an actual characteristics we found that the fitting was very good and we also said occasionally we would use a volt constant voltage drop model to make or hand calculation simpler and occasionally we might also use ideal diode model especially in rectifier circuits and then we talked about clipping circuits. We also talked about both synodiode also being used in clipping circuits we finally talked about clamping circuits and voltage doublers. So, I would stop my lecture here.