Okay, this is the 23rd lecture and this is our problem session 6th, I hope the number is correct, on frequency response of small signal amplifiers we will work out one problem and then we shall work out a couple of problems on differential amplifiers. The first problem that I consider is question number 3 in tutorial sheet 6 and the problem is this, we have a Vs, 10k is the source resistance, 10 microfarad is the coupling capacitor, then the base is biased in a peculiar manner, there is a resistance of 100k, another resistance of 100k and the middle point is connected to ground through the capacitor whose value is 10 microfarad, the collector is connected to this point and this point is connected to plus 10 volt and the resistance of 3.3k, 10 meter is grounded, as you see this is the DC feedback biasing that is the current, the current that flows through 3.3k is I c plus I b and that I b, I c flows here, I c flows here and I b flows here, cannot flow this path therefore it comes to the base, we have done this kind of biasing, the only thing that was not done was this capacitor which is for obvious reasons to prevent AC feedback that is input signal cannot go to the collector directly because of this capacitor, output signal cannot go to the base because of this capacitor, okay, this capacitor is a bypass and then the output is taken from the collector through a capacitor again 10 microfarad, all 3 capacitors are 10 microfarad and then a 4.7k, this is the actual load and this voltage is V 0, the transistor parameters are beta equal to 100, I do not want that marble from there, beta equals to 100, V a equals 150 volt, C mu is 2 parts, C pi is 5 parts, C 0 is 0, no stray and R x equal to 100 ohms, even the R x is given in most of the problems, we conveniently ignore it because it increases our problem of analysis, okay, the first thing we have to do is to find the problem is to find out A V S J omega that means we have to find out all the frequencies, all the critical frequencies and we shall have 3 critical frequencies corresponding to the 3 capacitors here, okay, this capacitor is place the role of C E bypass, you see the usual biasing is if the resistance comes here, then we require a bypass at C E, C E bypass was avoided but one capacitor have to be introduced here, so the low frequency response shall be affected by this capacitor, this capacitor and this capacitor therefore I expect that there shall be 3 critical frequencies omega L 1, omega L 2 and omega L 3, let us call these capacitors as C 1, C 2, C 3, we therefore have 3 low frequency critical frequencies omega L 1, omega L 2, omega L 3 corresponding to the 3 capacitances and there shall be 2 high frequency critical points corresponding to C pi plus C m, similar capacitance C pi plus C m, we will combine them, we do not want to analyse 3 node circuit and the other critical frequency at high frequency shall be due to C mu plus C naught at the output, C naught is fortunately 0 therefore we expect that omega H 2 corresponding to C mu plus C 0 shall be much larger than omega H 1 due to C pi plus C m, these are the qualitative observations from the circuit, therefore what we expect is because the capacitance is 2 puffs, it is much smaller capacitance as compared to C pi plus C m, as you will see C m will be very large, it will be about 200, I am sorry about 50 times C pi, okay, we will see this but in general qualitative observation of the circuit reveals that A V S J omega would be of the form A V S O divided by 1 minus J omega L 1 by omega, 1 minus J omega L 2 by omega, this subscript corresponding to the corresponding subscripted capacitors, 1 minus J omega L 3 by omega multiplied by 1 plus J, you must distinguish between the low frequency and high frequency, it would be omega divided by omega H 1 and 1 plus J omega divided by omega H 2, is it clear? Any more explanation needed? You must be able to write this expression just by looking at the circuit, just by looking at the circuit. How are we sure that there are no zeros? Yes, we are not sure unless we draw the equivalent circuit but we have experience with the equivalent circuits of this kind, we have experience already, if C mu was not absorbed in C m, the Miller capacitance and the output capacitance that is C mu was not absorbed in C 0 at the output, then we know there is a 0 at minus G m divided by C mu plus G m divided by C mu, we have already done that but since right from the beginning, we look at the complication of the circuit and we say sorry we have to use Miller, we cannot use a 3 node circuit and therefore that 0 shall be avoided in the analysis, anyway this is much further from any omega H that you can imagine and therefore this 0 will not come, the first thing that one should do is to find the parameters and therefore we require a DC analysis, let us look at the DC analysis this is 10 volt and this current is I sub C plus I sub B therefore I can write 10 volt as equal to this drop, drop across 3.3 plus the drop across 200 K, this 2 can be combined as far as DC is concerned plus 0.7 and that shall give me I sub B agreed, so my equation becomes 10 equals to beta is given as 100 and therefore I C plus I B would be 101 times I sub B, this has to be multiplied by 3.3 K, this gives the drop in 3.3 K, then the drop in 200 K is due to I sub B and then we have V B E which is 0.7, this gives me I sub B as equal to 17.4 micro amperes, that means I sub C which is 100 times this would be 1.74 therefore I sub B, I sub C is 1.74 milli ampere, you must now check because of many hurdles that we have passed, we have seen circuits which behave very peculiarly, we go ahead blindly calculating but ultimately we find that one is cut off and one is saturated as in question number 2 of minor 1, therefore V C E we must check this although it is not required in any of the parameter calculations, we must check this routinely and we must say that this is not neither negative nor comparable to 0.2, okay, V C E is 10 minus the drop in 3.3 K which is 3.3 K multiplied by 1.74 milli ampere, actually we should have made 1.754 okay because it is I C plus I B but well I did not do it, you can do it, I found this as 4.25 volt, this is not critical to include 1.754 that is I B also because the voltage is much above the saturation voltage, okay. Once we have found this, once we have found I C, we can find G M as I C by V T, you take V T as 26 millivolt, then it becomes 0.067 mole okay, then you can calculate R Pi as beta divided by G M, beta is given as 100 and the result is 1.494 K and R 0 can be calculated as V A divided by I C, 150 divided by 1.74 milli ampere and this comes out as 86 K, the 3 parameters of importance have been obtained, these all these 3 depend on I C therefore we had to calculate the DC conditions, okay. Now let us look at the mid-band equivalent circuit, to find out A V S 0 okay, the mid-band equivalent circuit would be like this, V S then at N K what would be this resistance, it is not the parallel combination now, at mid-band 100 K goes to ground, is that clear? Because of that capacitor C 3 it is 100 K, not 100 K parallel 100 K okay, alright, this point must be recognized, then we have R Pi which we had found as 1.494 K and the voltage across this is V Pi with this polarity, we have the output current generator G M V Pi, G M is already found at 0.067, 0.067 more, then we have, well we will combine everything into 1 resistance, R L prime is R C which is 3.3 K parallel 100 K shall come in parallel from the collector to ground through via C 3, then we can also include R 0 which is 86 K, this is 3.3 K R C and this calculates out to 1.86 K, oh we must take that into account, yes parallel 4.7 K, that is how I get 1.86 K okay, therefore the, I hope I did calculate, yes, now therefore A V S 0, A V S 0 would be minus G M R L prime okay, minus G M R L prime multiplied by V Pi divided by V S, agreed? So this is, this is calculated by inspection, by observation, no equations indeed, let me write this, minus G M R L prime, I am writing this separately because of, I am not writing numerical values right away and I am not calculating because of a specific reason, what is the reason? I need this value, why? For calculating the miller capacitance, so I keep it separately, these are tricks of the trade, otherwise you will have to go back and calculate again, so I do it in one step, then my V Pi over V S is 100 K parallel 1.494 K divided by R S which is 10 K plus this resistance, 100 K parallel 1.494 K and this comes out as, this is minus 125 multiplied by this value and I calculated this to be equal to minus 16 okay, I do require this value 125 because I have to calculate C T, let us calculate in one step, C T the total input capacitance is C Pi plus C Mu 1 plus G M R L prime, I know everything C Pi, I know C Mu, I know G M R L prime, this becomes 257 path, this is the equivalent capacitor and therefore the Omega H 1 due to the input capacitance would be given by, Omega H 1 would be given by 1 over C T 257 path multiplied by the equivalent equivalent resistance across it which is 10 K parallel 100 K parallel 1.494 K and my calculation gives this value as approximately 3 times 10 to the 6 radians per second. The other high frequency critical point due to R L prime and C 0 plus C Mu which is at the output is equal to, is this clear or I have to show the circuit again? It is clear, so this should be C Mu which is 2 path multiplied by, I had calculated the equivalent resistance as 1.86 K and this is greater than as you can see very easily 250 multiplied by 10 to the 6 RPS, so Omega H 2 can be ignored, if you so desire and Omega H the high frequency 3 dB point would be approximately 3 times 10 to the 6 radians per second but since the question asked is to find AVS J Omega, you must include this okay, you must include the factor 1 plus J Omega divided by 250 multiplied by 10 to the 6, is the question clear? The question I did not ask find the high frequency 3 dB point, no, I asked find an expression for AVS J Omega and therefore this must be included, if the question was to find the high frequency 3 dB point this is perfectly alright okay, now let us go to the low frequency. Sir in recent analysis you are applying both the methods of time constants and middle approximation on the time type? No, no, the time constants method okay, that is a good question, let me answer this question, you see the only way that this equivalent circuit differs from the high frequency, if I want to convert it to high frequency, I apply this approximation of C T and this is C 0 plus C 0, now it is no longer the method of time constants and the analysis are exactly the same, they are exactly the same, if you write V Pi over V S this critical frequency income, if you write minus G N times this, this is the other critical frequency Omega H 2. So it is not, after the approximation the method of time constants and the method of analysis are the same, as I said the method of time constants has to be used when there are many capacitors, this is as good as analysis, it gives the same results as method of time constants and this is what was used to validate or give confidence regarding the method of time constants, that in simple cases the results are identical, in complicated cases no, sorry they are not identical, they differ, okay. Now the low frequency equivalent circuit, as I said in low frequency equivalent circuit there are 3 capacitors now and they are coupled to each other and therefore there is no other way but to consider the effect of each at a time, fortunately here you can consider the effect of C 1 and C 2 in one go, fortunately. So first you assume that C 3 is short circuit, let us see what the equivalent circuit is, equivalent circuit as long as C 1 and C 2 are decoupled from each other while the method of time constants and method of analysis are the same and fortunately we can do that here, you draw the equivalent circuit V s, it is always good to draw the equivalent circuit, 10 k then you cannot miss anything, 10 k, 10 micro farad, this is C 1 then we have the parallel combination of 100 k and 1.494 k and this voltage is V pi then we have the g m V pi, we do not require the exact values of this because g m does not determine the time constant then we have, now we cannot combine 4.7 k here because we are considering the effect of C 2, so 10 micro farad, this is equal to C 2 and we have a 4.7 k, so this resistance is the parallel combination of R 0 which is 86 k parallel R C which is 3.3 k parallel 100 k, anything else? No, that is it and this calculates out to 3.08 k, now here is a point to note, we have to calculate this separately, whereas we also calculated the parallel combination of this and 4.7 k, we could have done it in one step, anticipating that this resistance will be needed, we first calculate this, then we calculate 3.08 parallel 4.7, rather than putting 3 resistors in parallel and 4 resistors in parallel, we could have done that, just like we calculated A V S 0 alright, these are tricks of the trade with experience, you will know that I should not calculate the 4 together, I calculate 3 of them because I require this value separately and then the 4 is fine alright. Now you see that C 1 and C 2 are decoupled and therefore the critical frequencies due to C 1 and C 2 can be calculated from this circuit alright, omega C 1, omega L 1 for example due to C 1 would be 1 over, the capacitor is 10 micro farad and the given in resistance not the method of time constants or otherwise, it is the same, given in resistance would be 10 k plus 100 k parallel 1.494 k and this calculates out to 8.7 radians per second, omega L 2 the second due to the second capacitor comes out as 10 micro farad once again multiplied by 4.7 k plus 3.08 k okay, the current source is opened and this calculates out to 12.85 radians per second alright, these 2 are comparable, they are comparable, even omega L 1 squared and omega L 2 squared, one cannot ignore one with respect to other because the ratio is simply 1.4 okay, however these 2 are not the only only culprits, there is a third culprit C 3 which creates a complication in the calculation of omega L 3 and we have to draw that circuit separately and it is instructed to consider how this circuit is drawn you see, as far as C 3 is concerned if C 1 and C 2 are shorted then by equivalent circuit draw this carefully, we have this 100 k like a dumbbell 200 k on 2 sides and this is my C 3, this is the position occupied by C 3 okay, let us draw C 3, C 3 which is 10 micro farad then on the left, on the left comes R pi which is 1.494 k, this is R pi I am sorry this is V pi and comes at 10 k in series with V s, I am drawing the equivalent circuit considering C 1 and C 2 are short and C 3 effect of C 3 and on this side on the other side we have the G and V pi, G and V pi then in parallel width, how much is this, this now will contain 4.7 k also, so 1.86, 1.86, 1.86 it will not contain 100 k then, it will not contain 100 k, wonderful, it cannot contain 100 k now, very good, so we have to calculate the value, this gives us another lesson that we should not have calculated those 4 resistances at one time, we require these 3 values separately okay, who is this boy who pointed out this main, okay, that is very good, I appreciate it, we have made a great blunder if you have included 100 k, why, why great blunder because R 0 is comparable to 100 k, is it not 9, 86 k, suppose R 0 was not there, if it was simply R C parallel R L then the error would not have been much by ignoring that okay, so we have to calculate this and now the problem is that looking from here, looking from C 3, what is the resistance that it sees and therefore what we have to do is to find out the equivalent thing in it, we have to short this and then we have to replace this by lengths of a voltage generator V and calculate the current I, then V by I will be equivalent resistance, it cannot be obtained by inspection unfortunately, so let us draw a clean circuit on a clean slate and then proceed, we have a V and this current is I, on the 2 sides there are 200 k's, 200 k's then we have a G and V pie, we cannot open it because this is a control source, V pie is not 0 okay, what is V pie, V pie is the potential division between 100 k and the parallel combination of 1.494 k which is R pie and R S which is 10 k, so this is V pie, this is V pie and V pie is not 0 therefore we cannot make this open and in addition we have the parallel combination of R 0, parallel R C, parallel R L, what we have to do now is to write okay, I can write V pie in terms of V by inspection correct, this would be 10 k parallel 1.494 k divided by 10 k parallel 1.494 k plus 100 k multiplied by V, so V pie I know in terms of V then I have to write a node equation here okay, I have to write I as equal to what is this current, this kind is V pie divided by this parallel resistance, so V pie divided by 1.494 k parallel 10 k, it is this current okay then this current is if I call this voltage as V 1 is V minus V 1 divided by 100 k, I now want to know what is V 1 okay, we also see that this current is equal to G m V pie plus the current through R 0 parallel R C parallel R L, so my third equation would be V minus V 1 divided by 100 k equals to G m V pie plus V 1 divided by R 0 parallel R C parallel R L, there are 3 equations now and the way to proceed and the systematic way to proceed is to replace V pie, so I have one equation to second equation and this is the third equation, from 1 I replace V pie, wherever V pie occurs I replace V pie alright and then from the third from the third I get V 1 in terms of V, V 1 in terms of V and then I substitute in this equation, I divide both sides by V, that is the input conductance, the reciprocal of which is the input resistance, it sounds complicated but it is not complicated because you will work in terms of numbers, I have not simplified this but I have I must assure you I have calculated and my calculation after some calculator approximations and slipiness approximation, my calculation gives omega L 3 as approximately equal to 2 R p's, so 2 8, what was the, what was the other case, 12.85, so who controls? No, this is the answer I was expecting and I wanted to correct, no it is the highest but even that does not control 12.85 because there is a frequency close to it, so this is a fit case, these 2 radians per second can perhaps be ignored compared to the other 2, 8 and 12 because 1 is 4 times 1 is 6 times, where we have calculated R 0 plus R c parallel R L, yes, 100 k comes here, 100 k comes here, this you have to calculate independently, this is what I said that you learn 2 lessons that you should not go ahead calculating the equivalent of 4 resistances because equivalent of 3 resistances are also required, you have to do it in 2 steps, okay, so who controls, who controls the low frequency response, omega L is controlled by omega L 1 and omega L 2 because omega L 1 by omega L 3 is approximately 4 and the square is 16 and omega L 2 divided by omega L 3 is approximately 6, the square is 36, okay but the total a v s j omega now has to be written in terms of what we found out for a v s 0, then 1 minus j 2 divided by omega that is omega L 3, 1 minus j is 8.7 divided by omega, 1 minus j 12.85 divided by omega multiplied by 1 plus j omega divided by what was omega h 1, 3 into 10 to the 6 and 1 plus j omega divided by 200, I did not calculate that, I showed which is greater, so you put that value, whatever value, this is the complete answer, yes, that is right, what do I do What do you do, you ignore, okay good question, how do you calculate omega L, what you do is you ignore this, you ignore this and you ignore this, is that the high frequency, then you have 2 frequencies, 2 cut off frequencies and therefore you have to write the equation a v s square of this, square of magnitude of this is equal to 2 and solve for omega L, okay, that is it, exactly like the question number 3 in the minor. Now in the rest of the time we work out a couple of problems on differential amplifiers because I find that we will come to the tutorial on differential amplifiers only in the next week, so let us do some differential amplifiers and you will see that this is a different brand of calculation, even the DC calculations are somewhat different from what we have done so far, the first question, draw the circuit with me, a simple problem R sub C, R sub C, this is 10 volt and R sub C is given as 100 K, not the large value of R sub C, this is a micro circuit, it is an integrated circuit, this R sub C is not a lumped resistance, it is a, what is it, it is another transistor, it is a current source, this output input is 100 K but that we will see later, suppose it is discrete, even in discrete differential amplifiers what we are interested in is voltage gain, not power gain, not voltage level or current level and therefore your signals can be micro volt order and your I sub C1, I sub C2 can also be in the range of micro amplifiers, alright because it is voltage which is of importance, okay, so R sub C is large, you have 2 transistors, it is a discrete circuit let us say, okay, we will calculate this is a discrete circuit, there is an R sub EE and the current through this is 100 micro amperes, this is equal to I sub EE and this is taken to minus 15 volt which is minus V EE, this is plus V C C and of course because it is an, because it is a differential amplifier, the 2 inputs B1 and B2, they are left as terminals to be connected to sources, the differential voltage is to be connected between these 2, as far as DC is concerned unless the source resistance is specified, this would be considered as grounded, okay, so that forms the heart of DC calculation, now the question is capital T is given as 25 degree C that is the normal room temperature which means that you can use V T equal to 26 millivolts, VA is given as 100 volt which means you know what is R0, R0 has to be combined with R sub C and they are now comparable, okay, so VA can no longer be known, beta as I said you must require very high betas for this transistor beta is 200 and the question is to calculate Q points of each transistor, naturally the Q point of any 1 transistor will suffice because the 2 are identically biased, Q points of each transistor you require the value of REE to be able to support the 100 micro ampere current, what value of REE is needed with these 2 supplies, 10 volt and minus 15 volt, note that they are not identical, in ICs usually they are identical but to bring variety into experience we assume them to be non identical and you also want the value of R ID, the differential input resistance, we require the value of A sub D, the differential mode voltage gain and fifth we require the value of the common mode voltage gain A sub C, okay, this will completely analyse the amplifier, so the first thing that we should do is to check the Q points that is find out I sub C and VCE, now to find I sub C our procedure would be slightly different from what we have been using earlier, you see what we do is we write, first we write 10 volt equal to, do you know this, this current, how much? AC is given, AC is 100 K, this must be half of this, 50 micro ampere because beta is large, okay, so I know RC, I know 50, I know the current and therefore I know the drop here, then what I want to find out is this, VCE, okay, so 10 volt is equal to the drop in RC plus VCE, then we could have gone through this but we do not, we go via this because I know as far as DC is concerned this point is grounded, so this voltage is 0.7, with minus and plus, agreed, that makes a shortcut, I do not have to go through this, so my VCE equation becomes 10 equals to 100 K multiplied by 50 micro ampere plus VCE then minus 0.7 where I go from the emitter to the base, which gives me VCE as equal to 5.7 volt, wonderful, so 5.7 volt and 50 micro ampere is the key point of either transistor, now to find out REE, yes, it is not clear, okay, 10 volt, how is this connected, plus 10 and negative ground, so 10 volt is equal to the drop in RC plus VCE, we have come here, when I go to ground back via the base of transistor 1, that is why minus 0.7, this voltage is 0.7 okay and I found a VCE, how do we get 50 micro ampere, how do I get 50 micro ampere, this current 100 micro ampere is approximately twice I C, I C 1, actually it is IE 1 plus IE 2 but since beta is large, this is approximately I C 1 plus I C 2 are identical and therefore it is half, any other question, now to calculate REE, to calculate REE what we do is, we come from here and go to the negative supply, we write a KVL, so what should I write, 0.7 plus REE multiplied by 100 micro ampere, then I have to go to ground via this supply, minus 15, plus minus, plus minus, then minus plus therefore minus 15 which gives me REE as equal to 143 K, is this point clear, okay, I come from the base of transistor 1 from ground 0.7 plus the drop in REE plus whatever potential this point is at, this is the minus 15, so that is what I write, you have to be careful in this calculations okay, you have to find short circuit, short short cuts, short circuit, short cuts okay, that is what distinguishes an engineer from a non-engineer, I will not say scientist, a non-engineer okay, so I have found REE and once I know these parameters then other parameters calculate very easily, GN is I C that is 15 micro ampere divided by 26 millivolt and this calculates out as 1.92 millimole, once I know GN then I know AD, AD is minus GN, the differential mod gain minus GN RC parallel worth R naught, small R naught, I cannot ignore it, RC is 100 K and what is small R naught, GA was given as 100 volt okay, 100 volt divided by 15 micro ampere which is equal to 2 megs, 2 megs is 2000 K, 20 times this but even then because of high gain calculations it includes this, be kind to R 0 and do not ignore it, this in my calculation this comes out as minus 183 okay, then I require an R ID, R ID which is equal to twice R pi, now what is R pi that is 2 times beta is 200 divided by 1.92 millimole, you see how large R pi is approximately 104 K, why does it happen because of the low values of collector current okay, so no longer any of these can be ignored, R X fortunately is an ohmic resistance, it still remains 100 sub ohms, it does not depend on current but R pi cannot be ignored, R 0 cannot be ignored and this is 208 K, this is a high input impedance amplifier, finally I have to calculate the common mode gain which as you know is minus GN RC divided by 1 plus twice GN times REE, this is also an approximate expression but fairly accurate, minus GN RC already calculated minus 183, 1 plus 2 into 1.92 into 10 to the minus 3, 1.92 millimoles multiplied by 143 multiplied by 10 to the 3, yes, yes that is correct, thank you, that is why I used 183 here, I missed that term, 1 plus 2 GN RA and how much is this, 143 approximately 0.3, it is a fraction, you see this 10 to the 3, 10 to the 3 cancels, 3.8 take this as 4, 4 times 14 516, so approximately one third, approximately 0.3, minus 0.3, what is the CMRR then? 183 divided by 0.3 that is more than 500, CMRR is more than 500, okay, the third question, I will indicate the question and leave it to you to work it out. Third question is design a differential amplifier, no longer analysis, what I want is given you have to give me the circuit, design a differential amplifier that meets the following specs, I shall briefly discuss how to proceed, the specs are RID equal to 2 meg, differential input resistance must be 2 meg, A sub D differential gain I require minus 500, CMRR I require 54 decibels, these are the ways people specify practical specifications and V C E Q that is the transistors Q point must be a very safe value 5 volt is specified, assume that the transistor beta is 200 that is you are given transistors a lot of transistors, a lot not many I mean a lot, maybe a lot of 10 on that of 12 identical transistors in the beta is 200 and VA is 150 volt, this is what is given you are required to design, now what does design mean, design means you will have to specify V C C, you will have to specify V E E, you will have to find out R E E, you will have to find out R sub C what else, that is all, that is all there is to it, okay how do you proceed, first, first from this specification you know what is R pi alright and if you know R pi and you know beta therefore you know GM, if you know GM then you know I sub C the collector current okay, agreed? From R ID okay let me draw the chart, from R ID find out R pi then combine the information on beta to find GM, combine the information of R pi and beta to find GM, from GM you find out I sub C okay alright, now V C E Q is given right, therefore from V C E Q and I sub C, no, no, can R C be found out? No, V C is a V C condition, V C C is equal to I sub C multiplied by R C plus V C E Q minus 0.7 and therefore from this you can find out R sub C okay, then wonderful, so you cannot do that, no, V C C has to be found out, from the gain A sub D minus GM R C parallel R0, R0 is known because you know I sub C and V A has to be given and therefore and GM is known therefore from AD you can find out R sub C and if you know R sub C then combine this with the given information on V C E Q and I sub C to find out V C C, next how do you find V E E? From this now wait a second, from the CMRR it is given in DD, we first have to convert it to a fraction, a number okay, first have to convert that is 54 equal to 20 log 10 of CMRR, from which you have to find out CMRR as a number and that CMRR is equal to how much twice this have to be here at the end of your names, it is scratch it and the number and say AD upon AC. No, we do not know what is AD, it is CMRR, CMRR is twice GM REE, so if you do the CMRR and you know GM, you know REE okay, CMRR was AD upon AC minus GM R C divided by okay, AC was minus GM R C divided by 1 plus twice GM REE, 1 is known and therefore the ratio is twice GM REE, since you know GM, since you know CMRR, you can find out REE and if you know REE, finally you find out V E E and the design is complete, would you care to stop a minute and note down what my calculations gave okay, my calculations say that V R sub C is equal to 2.7 meg, then V C C is equal to 17.3 volt, REE is equal to 1.25 meg and V C V E E is 13.7 volt, not very nice numbers but this is unfortunately what the design is. Do you require anything else? Okay, that is all for today.


They were back were alive. This is community matters and like in the fullest extent, you know, what is the community anyway, it's a group of people that have some, some sort of common bond, who live together and enjoy things together and suffer together and they have their life experience together and the community is like the, the essential group for humanity. I haven't thought about it, but when I'm with Hema Kubera, I think of things like this, that more specifically is Hema Kubera del Barrio. Buenos tardes, Emma, how are you? Buenos tardes, Je, muy bien. You have a Spanish last name, at least for me, I always say Fidel. Okay, in the Caribbean it was really important. Yes, I think it still is. Anyway, Hema's a filmmaker if you didn't know that and we're going to talk today about pathways for filmmakers. You know, I was thinking at first pathways to the stars, but the filmmakers are in their own way the stars, you know, that's the point. So we're going to talk about pathways for filmmakers here today. So first, a little bit of background. Emma is from Madrid originally, am I right about that? Yeah, small town north of Madrid called Medina del Campo, but yeah, around that area, the center of Spain. Yeah, and somewhere along the line she became fascinated with creativity and filmmaking and of course, at least for Hema that that means taking a different view of life than most of us. So let me just get right to that Hema, your view of life is different. How is it different? What is it? Can you articulate that? Well, I see life with a lot of filters. I have a picture of mine when I was like six years old in my father's hometown. We're in the sunglasses. I love the picture because it informs me about how I needed glasses and lenses to see things even when I was a kid. It's very difficult for me to see reality. I live kind of a little bit in a fantasy world sometimes. Well, no wonder that I choose to make documentary films because it's all about reality, but still you tell the story through your lens. Well, what is reality? Reality is different from different people. I suppose there's a continuum there. Well, there are absolutely realistic and boring. Sorry. And there's the ones who are out there in a fantasy world interpreting reality in a kind of organic way. And I would put you on this side. But I suppose there are people in the middle who can appreciate both sides of it. At least some of the time they can be a little in the fantasy world. The beauty of film is an documentary is that reality to me is connection. It's connecting through emotions, through sound, through ear, through touch. And I am not very successful at doing it in my personal life sometimes, but I think I have kind of like a little bit of a gift to do it through film. Touching people through film. So, I mean, do you want to send the same takeaway message each time, or is it different each time? How would you like your viewer to react? Would you like him to come into your reality, your fantasy world? What would you like to change in him? So every time I find a story that I want to dive in, and for me it's a deep dive, because it takes me whatever it takes me to make a film. I consider each film like a universe. So I go in and I have an idea sometimes of what it might be. But what I love about what I do is that it forces me to be flexible, to be in constant connection with reality with if I'm making a film about you, I need to find out who you are. What is your essence? And then with the collaboration of my team, not just the characters, not just the people that I interview, but also my editor, my cinematographer, everything that happens. The people that facilitate the story, I need to be really adapting and being flexible. So I feel like film allows me to kind of like work on myself, you know. You invited me to talk about the path in filmmaking. I was talking to my mother in Spain today and I said, oh my goodness, the path to filmmaking is, I would say that it's like there is this expression in the Bible. I think it is like the ways of God are mysterious. I just felt like, I could say the same thing about film is like the paths are so, you know, there is a business side to it, there is an art side to it. There's a language of cinema that is there, but the paths are so very different for everybody. And to me, I feel like what I do helps me see reality. Even though I express it through a medium that is a lot about dreams and about, you know, the magic of cinema. Indeed, it is magic. So, so how would you like to change me by your movies? How would you like to open my consciousness? How would you like me to see the world differently, you know, by watching your movie?  I think one of the challenges that I've had in hindsight and when I talk to some of my friends is that my films don't fit easily in boxes. And that has been a difficulty that I face, because I get a lot of rejection also because of that rejection from the, you know, festivals from funders. They're all wrong, you know, they're all totally wrong. No, no, it's just how it is, you know, they are like things and they're important things in the world. And sometimes for me, I think I make films that are very, I love the stories that I tell and the people whose stories I tell. But I think I like multi-layer stories for me as successful comment after somebody watching a film is like, oh, the film stayed with me for three days. Oh, I woke up and I had a dream about that film. Oh, I thought I hated all fighting but then after I watched the film, I just didn't even know what to say. I'm not a filmmaker that is going to give you answers. But I hope that when you go to see the film, your world will open up to something that is already there, but that you get to experience it through emotions. And through the beauty of the language of cinema, I am very lucky to work with really amazing editor is fantastic only the composers that I've worked with. Everybody that I work with, I'm very like. How do you select them? What are you looking for in them? Sensitivity, flexibility, a skill, of course. And more and more as I go, as I grow older, they're good people. Because I've had all kinds of experiences. There's a lot of ego. So if you give me, okay, somebody that has really good intention, maybe not, doesn't know everything about something, but it's going eager to learn it, I will pick that person. But I'm also with my team, I always expect the best, you know, I work with very talented people that add to my craft. You know, my films, I'm finishing now a feature lens film that I've been working on for eight years. It is a lot to them. I'm very difficult sometimes because I'm very much of a perfectionist so I would not give up until I will make any change I need to make. And once I finish the film I never touch it ever again. How do you know what is finished? I know it. You know, it's like, I know it because I have maneuvered it so much like I have been like so much going through it, going through it, going through it, we've tried every single thing. But at some point I know like it's what it is an amazing feeling that I've had with all the films that I've worked on is that when I start the film is like, I sense a story. When it ends, it's not the same story. But when I watch it in the big screen, it is the essence of what I wanted to say. I don't know how to explain that. But it's an amazing film, amazing feeling, and that happens because of the people that I work with. For instance, today's been an amazing day because as I said, I've been working on this film that has been titled Homecoming that now we're going to title the island in me. I haven't announced it yet. The island in me. And Todd Sikafus, who is an amazing composer, just finished the last cue. And now my editor is putting it there. We're finishing the credits. And my films are where they are because of also all the beautiful collaboration of the people that's that hanging there. And we thought I was like, we're talking about music and I was just giving him like my what I like for the ending credits I want something that I don't want something like the beginning I want something that will just be the memory of all the experiences that you've had through the end. And I just had to say that to him. And in less than a day he just came with came out with something beautiful, of course, is brilliant. So, you know, I work, I look for people that are never going to give up that have sensitivity, of course, a skill in the craft. And they're good people, because I think good people in the sense like that they have integrity that they can express their opinions I always say you tell me whatever you have to tell me I will always decide, because I'm the director right producer blah blah blah. But I want them to tell me because if you give the best in you my film is going to be better. It strikes me that when you say you want them to be good people. There's another dimension to that. And that is, living your own life. You want to be surrounded, especially in your work with people who are good people. It's a, it's a question of taste it's a question of what makes a better life for you and maybe self interested in that sense. You don't want people who are not good to be around you. You want to be surrounded with goodness. Interesting that sense because I want, I want them to have the freedom that they need to find, you know, their muse, but also the intention is to make the best film possible. Right. So, and hopefully everybody will benefit out of that, you know. So you got something in the mail today Hema do you want to share with us what you've got in the mail as a surprise today. So last time I was with you we had just premiered the Hawaii International Film Festival, then the pandemic hit right about now I was in Spain, went to Spain, premier there, then the film our actual speaks has continued to travel through virtual film festivals is gone to. We got an award at the Ocean International Film Festival in San Francisco it was fabulous. Then the film went to one, the one International Film Festival. We received the grand jury award for best documentary short. And today, I thought like I want to check the mail because I knew that it was coming and since you invited me I was like maybe we'll be lucky to share this. It arrived in the mail I don't know if you can see with the reflection but this is the best documentary award from the one International Film Festival. And I see the title of the film there in large letters are a total speaks now. Yeah, it's a film that is about. There you go conservation practice the beauty and power and strength and resilience and wisdom of the Puka Puka people and in terms of. Sure, the island of Puka Puka we spoke about it. And the film has also, you know, been to continues to go to virtual fun festivals and one thing about this rear is that is always changing I mean live reality so we change it but so much with the pandemic when we hit. A lot of things were canceled and others had to make the decision do I wait, do I just jump into this virtual world and see what happens. It was an experiment and it's been a really beautiful surprise. The film has gone to Tahiti, the FIFO Internet, Tahiti Film Festival, and also which is premiering Australia and of course I couldn't go to any of those places I hope that I will be able to go with my next film, but the beauty of the pandemic is like with Australia we premiered at the Melbourne Women in Film Festival and I couldn't go. But then I thought well there is this beautiful Puka Puka family that is from Melbourne and that they can go in for for me so I invited Lina and Malina to go to the premiere and they represented their film. And so anyway, another thing about filmmaking is like, I mean, this is nothing new but just we have to always be open to what might happen. In that particular film you found a gem kind of a little tiny precious gem in the middle of nowhere and not everybody has a chance to go to Puka Puka or even know about it and you chose that because it was I guess at least in part because it was largely unattainable by mostly most of us. And you shared that there was a sharing thing you found the essence but you also shared. And you know I find that really a big part of at least the way I perceived filmmaking to happen to be of value. But I want to, I want to, I want to tell you about something I did in preparation for our discussion today. I went back to early days of think tech really early days. And friend of mine put me in touch with a film named Fred Weissman WISEMAN Weissman is an acclaimed filmmaker. I'm not sure that it's documentary probably is. He's a law graduate he went to Yale law school, and he taught law after that and one day, he decided he had to go to his next chapter and find more. So he became a filmmaker and one of the early films he did probably. He's kind of senior now. One of the early films he did was something called Tittacard follies. And it was just an absurd name for a film about an asylum for the criminally insane. And they let him in. Nobody could get it. He got in probably because he was a lawyer and all that. And he spent weeks and weeks and weeks interviewing people they let him do it. And he had clips everywhere. This is before electronic films clips everywhere. And he spent a year year. No, I should say many years evaluating each one of these clips and trying to put those elements together into a meaningful film and he did, you know, he won awards with it. And I wonder what the comparison is between that kind of approach what happened to Weissman. He's made like 40 films.  And you take a lot of film, and then you develop a concept that you take the film and you put it together in such a way so that it represents politically what you personally have found. Am I right? What's coming up for me as we're talking is, yes, I totally connect connect with what you're saying. And in this case Puka Puka is called remote island. You know, we're all connected by water so the concept of remote is very controversial because we are connected right but, but when you said that I thought I always enter remote islands, even even when it's like we'll fight in, for instance, it's a world that has not been treated with film. So, and there is an immersion that needs to happen. What's happened to me, my first films were films that I found in the news. You know, and I am trained, I'm a trained journalist. So I know all about the ethics and that helps doesn't it. So I love coming from journalism. But the shift that I've seen in me is that that my last three films have not been films that have that I found in the news. When I did automatic cake. I knew auto, and of course auto is very popular in Hawaii, but I have to spend go and spend time with them and I work on that film for like five years. This was the cheesecake man. Yeah. So it was like, you know, I have to get to know him. I don't know how, you know, and not every filmmaker is like that. There are some filmmakers that go. They know how to cut a scene, there's like three clips, you know, 30 seconds, two seconds that that that that. And I have some friends that I'm like, why don't you do it that way. I don't know. I have to go and be with auto and just film for until is the process is everything for me in the process. The story arises for me, and then my editor bless her heart, you know, is like helps me with putting together the story. Puka Puka, there was is a film is a is a place in the world that has never been documented in film is hardly in the newspaper, Google it, you can even find her to get there. So I got into the story because of a very personal connection you'll find out when the island in me comes out. So these two beautiful women Johnny Frisbee who was in the show and Amelia Borowski, who I know very deeply and personally that's why I got in there but when I got in there. The first five weeks I was there. I realized. This is not enough for me. It's not enough for me to be here for five weeks the place was so rich that in two years later I had to go back and live there for five months and really get it in my body. I would always be an outsider, and that's okay. All my life I'm an outsider. I'm an outsider in Spain. It's like, but they really welcome me like in such a generous way. And I will go there. I live there. I even got injured there. They took care of me. It was amazing and out of all that. I think that is reflected in the film for me is the film about you. I will be in the film too. I never thought I would but now I must see it. It's about Amelia and Johnny and Puka Puka but I had this kind of moral question like I have a very intimate connection to the place and when I go to festivals sometimes it's like what is a spanier doing here in this specific a panel. And I'm like, well, I got there because of love really I went there and I fell in love also with the place. And you know the beautiful thing is that when people see the films they the comments that I'm getting is like they see the love in them. And to me, it's not a rational way of doing it. But it's my way of doing it. I don't know. Maybe, maybe from now on I'll do other films. I'll be hired by Netflix and I could just do films that are. But I'm up until now is just this process of yes, like the filmmaker that you're talking about emerging, submerging myself. Taking this deep dive and see was there. in the end, I'm a journalist, right? So I work with objectivity, like with balancing the stories, all of that. But in the end, it's through my lens. Yeah. It's almost as if the clips of film that you take over that period of time are your paint. They are your paint. And you mix them up, and you put them on the canvas, and then you turn them around and turn them around and turn them around until they finally meet your the lessons you have learned in taking them in the first place.  And I don't mean that in a, I really mean this, you know, when I this this film that is coming up, you'll see that I'm in the film, but it's really never about me. I think I do watch every film that I've made. It's about somebody else, right? It's about this film in Matadors.  It's about puka puka. It's about these two women. But they are reflections of me. It really is, it's like, it's kind of an amazing thing.  Then she would, she says, I will, I will keep fighting other balls. Yes, I will. That's me. Yes. That's you. I get it. I get it. I get it. So, you know, but so I do, but it's also not about me. It's about something larger. I think film helps me to transcend things, experiences. The larger part, the larger you and each film is a, it's kind of an expansion of your own life experience. So you made a lot of films. It strikes me that, you know, the subject is always way different. There's two of them that are really alike in any way. And I suppose that's the sort of a mission of yours is to explore the corners, different corners all the time. And the question now, this is a hard one. Now are you ready for a hard question? Let's try. Okay. Which one is your favorite? Oh my, I, you know, I love, I love all of them. I really do. When you watch a film that you've worked on for 10 years, five years, seven years, eight years.  You know, I feel like when I watch them again, I go through it's like a memory of that life, everything that happened, you know. So I really love, I don't say this, do not have to choose one. I really, I watch, I guess I'm at a recently on a Zoom event that happened here in LA with the Spanish Council. And Maripat was there on Zoom and they asked me, would you change anything 12 years later? And I said, no. And Maripat, they asked Maripat, would you change anything 12 years later? And she said, no. That's a statement. So I really love every film that I've made, you know, and but they get more layer, more layer and change. Well, I was gonna add, for example, you know, you have a character in a film. And you know, I mean, I observed this a lot in my television watching these days is too much. But that's COVID. So I forgive myself. But you know, the best ones are the ones where there's a dynamic where people change as they do in life. And you can see it and enjoy it. And you can put yourself in the shoes of that person who is changing as you are. And so and so you change, don't you? Yes. Yes. Everything changes, right? Like reality is always changing whether we like it or not. Now we've had a really good test of it with a pandemic. We started as a film, you have an idea, the idea changes, the character, the lives of the characters change, your life changes. When you get it to an audience, the audience will make it their own is no longer yours. You know, the impact of the film is beyond you. Yeah. And of course, the thing we talked about a little while ago is, what do you want to achieve? Well, in some tiny perceptible way, you want them to change. I want them to be inspired in a way, like not through me and my work, but like I want them to be like connect with another human, you know, like when you watch automatic cake and see auto and you see all his values, you know, and just his creativity and his ability to be happy and enjoy himself.  Like Mari Pat says, I do we want to do that? You know, it's like, it doesn't matter what you do, you just don't have to be able to fight, you don't have to be a famous person as a celebrity.  I went through, she went through that really hard time. I can connect with her because I was there. I want to humanize stories. Does that make sense? Yes. Find humanity. A noble, a noble commission. So where are you going, Emma? Well, where am I going? I hope to continue in the path that I am. I, in terms of my films, I hope that they continue to reach an audience. Yes, El Matador, just screen again after 12 years. Arato speaks, I want to do an impact campaign, take it into the school system that is available widely in the education system. Big idea, but little by little. Now I'm finishing the island in me. I hope it also has a life. And for me, I really, one of the most important things for me is personal growth. Like if anybody that knows me personally or lovers that I've had or like, it's like, it's kind of a pain because I'm always at this thirst for growth. You know, sometimes it's a little bit like limitless. But then, you know, I get like a lot of, I have to deal with a lot of challenges. So I hope things, I hope I continue to do what I'm doing professionally, but that it gets a little bit easier and that I continue to enjoy my life. I really think that regardless of the obstacles, my path moving forward is to keep working, doing beautiful things.  I mean, it sounds very subserving, but I took it away from you. Suppose I said, look, starting on Monday, no more films, that's it. Oh, could you develop in the same way? You know, I've tried to give up because I've been in moments that I was so frustrated and it was not easy. And I'm like, is this a sign that I should give up? It hasn't worked yet. Okay, forget that idea.  I hope, I hope I can continue doing it. I hope, you know, a few things with fundraising get a little bit easier so it doesn't take me years and years and years and years. But I really, you know, if I had, sometimes I said, like, God, in my next life, I want to be a, just make bread, you know, have a shop, make, get up in the morning, make bread, sell it. I'm not minimizing making bread. It's hard work. But it's just something that would be like more immediate, you know, more necessary, you know, like essential. Because sometimes this filmmaking business is just very, very difficult. So I thought about putting it up. Yeah, but I haven't, I don't want to really. I got it. I suppose now, I'm a young, aspiring filmmaker. Maybe I have a little experience. I mean, a lot of people do with the technology these days. And here you really have been around the block and you have found so much in it and you have created so much with it. So here I am, seeking your advice here in our half hour of intense conversation. But it's your advice. My advice, you know, I've had the opportunity in Hawaii to teach when we're community college in some of the classrooms of the University of Hawaii. And I always say, directing is overrated. Don't give it up, but learn a craft, learn a skill, become a camera person, an editor, a sound person, learn the craft so you can actually pay your bills, make it functional, you know. Also, when you're telling your stories, find things from the heart, things that you can, that will feed you regardless of what happens. Because filmmaking, somebody told me years ago, it's like every culture. And it's so true. And at the beginning I was like, what do you mean filmmaking is not agriculture? It's all about the technology? No, it's like you never know what, when you plant your seed, what's going to happen. It could be wasted. It could like grow and be shiny and very fruitful. But in the end, regardless of what happens with the external world, if you're happy, if you're happy, I always ask my students, are you happy with it? Like, and I don't mean in a shallow way. I mean, like, could you live with it? If you can live with it, that will sustain you.  And also surround yourself with other beautiful things in your life. It's essential. You know, it's just don't expect, because this world is a lot about external recognition and it's crushing. But if you surround yourself with things that you love, that will feed you and that will sustain you. And if it's meant to be for you, it will be.  There's always nutrition there. So, so, where can I see your films? Give me at least an opportunity to see some of them. Where can I go? What can I do to see your films? Um, you know, I am in the process right now of putting all my films on the web on talcual films. They're not there yet, but I'm working on it. One of my films, ella es el matador, is distributed about women made movies. So you can go to women made movies and it's on bimeo in their channel. It's also on my talcual films page. You can just go to the page and you can actually go to the link there. Um, Otomari cake. Um, I, and our Attila speaks, I, I need to put them on my website. So I would say just talcual films, sign up and then as soon as it's up, you will be able to know. Um, the island in me is, I'm now waiting to see where it will premiere. So maybe I can come back to you in a few months and say, Hey, this is how you can watch all these films. Oh, okay. I want that. Let's talk. I mean, what means as it is, it's a sweet expression. It's been, I could say, oh, Jay is talcual. It's just natural. Kind of like it doesn't have a mask. It presents itself. It means as it is. You know, we've met a couple of times before on think tech. And, you know, we talk about how people change and all that. And you do. And I'm always more overpowering than I was the last time.  You have a foundational solidarity, which is why I like you so much. Thank you. Thank you for having me. Thank you for having me. Thank you. Aloha.


Hi, my name is Eva and I'm an assistant professor at Kent State University. I teach classes in typography and graphic design and today I'm just going to talk to you a little bit about my background as a typeface designer and how that's influenced my thinking on graphic design and led me to re-work a couple of assignments for my students. So I'm going to just talk you through the three kind of characteristics or defining parts of the practice as I see them, how I see them relating to design pedagogy, what exactly I change about the projects and then show you some examples of student work. So to start off with, why that's super loud, I think one of the defining features of typeface design practice is an obsession with modularity and iteration. So as typographers you'll probably be with me on the idea that letters themselves are modules that build to make words and words are modules that build to make sentences and sentences are modules that build to make paragraphs and paragraphs are modules that function in the modular grid. But for the type designer this level of modularity is a little bit more fine grained and starts with the parts of the letter themselves. So if you as a type designer want to make a change to your end that changes all of the ends in the paragraph and changes the overall color of the paragraph and the texture of the type but it also changes anything that has a relationship with that end. The most obvious ones are things like the M, H, U and R and that kind of plays out and say you change the top serif of the ends and then anything that has a top serif or anything that looks like a top serif will change. Similarly the arches or the stem weights and so on and so forth. Basically the point being that all the letters in the typeface have an interrelated kind of complexity in their relationships with all the other letters in the typeface. So it's sort of systems thinking to a higher degree so it's this idea of iteration that's found in all design practice in typeface design practice is kind of magnified. So secondly type design practice is involved with abstraction and translation. So in terms of abstraction what I mean by that is that this is the interface of the font editor robo font and as you can see it's almost entirely black and white and gray. So type designers deal with making meaning and personality just purely through formal characteristics and shape. And secondly this idea of translation is that typography there's a well-known phrase typography is what language looks like and so as type designers you're thinking about translating meaning into shape and thinking about two forms of users so there's a very strong interaction with user interface design here. In terms the two users I'm thinking of are graphic designers who use the font products like tools and so you're thinking about how they're going to interact with open type features and how you're going to structure the typeface how many weights it's going to have things like that but then also how the reader will interact with it which obviously is of paramount importance to any typeface designer. And then lastly type designers are concerned with dealing in visual language and visual language obviously has many different meanings for different kinds of theory but what I'm talking about here is cohesion and consistency in building a tone of voice. So what I mean by that is if you look at two typefaces that might fall loosely into the same category like doko and chaparral here they're both slab serifs that are fairly monoline in weight and there are differences obviously but when you look at them up close you see the differences even more and these subtle differences play out at the paragraph level that change the typeface completely to have a totally different tone of voice and this kind of tone of voice is what I'm talking about when I say visual language or vocabulary that plays out in things like logo type design also and different weights within a typeface making sure that the tone of voice of any typeface is consistent throughout even if there is well obviously there's going to be a variety in the styles themselves. So those are the three defining features as I see them modularity and iteration abstraction translation and visual language. So how did those things parallel in type design or in design pedagogy? Well I see modularity and iteration as playing out in systems thinking which is obviously a catchphrase. Thinking about modularity and iteration and reflecting on process is a way of making flexible integrated and responsive strategies will help students with things like web design but also any kind of design really that has to do with making an integrated system. Abstraction and translation I see is playing out in design thinking so making the students aware that making is a form of research and creating a user-centered focus and this idea of abstraction helping to create new answers to ideal problems and then obviously lastly visual language we are as visual communicators aiming to be visually fluent and so an ability to immerse yourself in a set of shapes and a palette of personality based visual cues can help the students to develop identity systems, information systems, wayfinding, book design etc etc. So in reworking the briefs my main well I reworked two briefs I'll tell you a little bit more about that in a second but the main objectives that I had were to get the students to learn in a modular way so that one brief would lead to the next to encourage them to design and build personality modularly so just to focus on the usefulness of modularity and to encourage a reflection on process and the value of revision or mistake rather than seeing it as something to shy away from to encourage students to think in metaphor and analogy and to encourage a focus on user experience. So all of these things then will culminate in thinking about systems thinking as a flexible conceptual approach and promoting visual communication as an equivalent to verbal or written language. So the two projects were designed to work in tandem and the first was a two-week exercise and it was called rinse and repeat and that was a reworking of an existing brief called the creative process poster but when I googled creative process I got hundreds of thousands of examples of creative process in like flow charts then diagrams and tree diagrams and I just thought well that's just going to end up in more of the same so in order to get them to think actually creatively and really push them I want to just sort of throw them in at the deep end and then the second one was designed it's a seven-week project it was a reworking of an existing project called narration and mapping and I changed the focus from mapping to translation to try and put the idea in their heads that the designer is a sort of medium and so I'll start off with rinse and repeat and the focus here was to get them I just told them to find a mistake in a process and left a totally open-ended what they defined as a mistake or a process and I left the format completely open also so they really were just kind of thrown to the hounds and the hope here was that they would push push beyond their comfort zones and not just make emulative work to think abstractly in their visualizations to reflect on the iterative process and as a means of researching and to think about novel or unusual kinds of visual structures so Marianas think and overthink was kind of this really made me happy when she came up with this idea because I was like yes somebody gets it she decided that she would represent her mistake of overthinking in her process of living so kind of grand ideas here and she made a small I think six inch by six inch booklet that is designed to visually articulate the idea or the process of overthinking so her colour palette is all kind of like pastel pinks but they blend to make kind of warmer reds as you go through the book and she represents a thought as a singular node that has the potentiality for overthinking indicated by a dotted line around it and then as she thinks about it or overthinks that node then forms extra kind of connection connecting dots that come off of it and start to build a structure and as she overthinks the structure gets more and more complex until it gets out of control and all the connections start to break down and her mind gets troubled according to Snoopy there and she brings us through the process by and shows us this kind of like abstract and realization of her thought process by using colour contrast and very formal abstract visual language and then brings us to a culmination where she's letting go of thinking so it's just a really simple idea very well articulated I think. Lindsay's as the second of this I'm going to show two of the exercises since it was short and she focused on the mistake that she found in Chicago's train service on the L line where there are five stops called Western which obviously is a little bit confusing so rather than you know focusing on that as a mistake she decided to put a positive spin on it and turn it into a kind of a boon rather than a bus and she made a small booklet for the tourists to use so that if they got off at the wrong Western stop that they could make something good out of that and some of the things like this one here actually there's not much to see here maybe you should have answered yes to the last question just keep passing through so there's a kind of a tongue-in-cheek look at the whole thing but she maintains a consistent visual vocabulary that ties in with the train lines aesthetic and I think she does a good job of turning the idea of a mistake on its head so both of these projects show this idea of abstraction and translation and a focus on process and that was supposed to then build to lead into the next project which is a seven week project called narrate and translate in which the students were supposed to embark on a new experience new so that they would be able to reflect on the steps involved and then build an informational experiential artifact so again very very open ended and the format was totally open it should be dictated by the content and so the steps involved were that they should do an analysis and deconstruction of this experience visualize the experience in metaphor and analogy and try to think abstractly about what the essence of the experience is and structure and pace the delivery of information in a way that is conducive to the user having a sort of vicarious experience and then the whole thing is aimed at helping the students reflect on the role of the visual in the broader field of communication so Marianne again embarked on a trip to the Cleveland Botanical Gardens and decided to frame her project around the cactus garden there which is housed in a glass house so defining the essence of her experience she said that what you remembered most were the panes of glass in the glass house and this idea of unveiling or unearthing looking through a pane of glass and seeing this lush greenery on the inside so with that in mind she made a set of uh logo types that are all um in kind of a latin um they're all latin and they they refer to the idea of a place of life they vary it means place of life in latin and she was referring to the botanical naming conventions there and she used um this framing device throughout and she took all the photography herself and it's all kind of macro level photography that is um cutting off parts of the photo and kept the visual language consistent and very clean um the outside is almost entirely white and um when you open it you are unveiling and unearthing this giant plethora of plants on the inside and the um product works in a modular way in that it has three parts to it one is an app that you can use to scan the QR codes of the plants that you see um and get more information about them the second part the middle one there is a botanical exploration that helps you get around the place itself and tells you more about the plants that you see and auxiliary which is a set of useful tools to help you take photographs of plants to grow them and take notes and sketch um and this is the app that goes along with it which um can like maintains the same visual uh identity Jess's uh Hona beauty kit is something similar she decided she would make her own um homemade and natural beauty products and defining the essence of this experience as a kind of do it yourself getting back to nature taking reclaiming um your um ability to do things for yourself and not have to be a slave to consumerism she decided that she would make a product that empowered the user she made a very um nice consistent brand identity that has sort of mini brands for each of the products that she made but she gives them empty jars and um a list of ingredients and a dvd to go along with it to just explain how they can make all of these products themselves um and it's in essence translating what she went through this is just um making some softening lip scrub right there um and the idea of do it yourself is uh continue through the um hand lettering and illustration that she uses throughout the colors are also color coded according to um different kinds of feelings that you want to have come through and the logo type the little kind of um flower guy is supposed to represent rosemary which is the greek goddess of fertility i believe um so again lindsey's fine fresh food does something similar um she embarked on a three-week vegan eating experience and um in terms of translating that she felt that the defining characteristic of this experience was having to research for herself and be very mindful of what she was putting into her body so she decided to make a toolkit essentially that gives the um power back to the consumer and she um supplies them with a bag and a kind of book that has three parts to it um and translates it in a what i've called a multimodal translation that where the tactile qualities of the papers themselves and the fabric are all very organic and um feel very paired back and the um the illustration throughout is just that it's illustration rather than photography with the view to keeping it less about specific foods and more about just the general reflection on food stuffs and what you're putting into your body and it's broken into three parts so we see a little bit we read a little bit about her experience she gives some recipes as a starting point and then there's a section for notes at the back and a little pocket to hold all of your um ideas as you're going through the process yourself and then lastly um Greg's dissolution into the obscure uh he took part in a paranormal investigation um and went in with a skeptical uh approach and came out with a skeptical approach um but decided to make it a kind of a tongue-in-cheek look at it and he made um he decided that the essence of the whole experience was a sort of like fumbling in the dark and then trying to rationalize it in a scientific way so he wrapped the whole thing in a wooden box that's completely unmarked so you have to open it to find out what's inside and then it's got two levels so the top level there um the quirk board actually sits between those two levels and you read the investigation guide dissolution into the obscure first to assess whether your evidence is good or bad for the existence of a haunting and then if there is good evidence for a haunting you are instructed to please access the next level of the box and at the next level of the box you are supplied with a seance board and all of the spiritual items that you might need to conduct a seance so again it's this kind of modular set of ingredients that the user can use to um create their own experience and it translates his experience into something uh useful and in terms of visual vocabulary he makes good use of a kind of fairly um encrypted hand lettering style here where you have to sort of work to decipher what's being written out combined with a very formalist approach to typography that makes it feel sort of pseudoscientific um so um what did we learn since we're in the thinking of learning here and the students the stronger students learned a lot from the process and had no problem with running with abstraction and open-ended briefs but for the weaker students I noticed that not having specific deliverables and not having specific milestones along the way was kind of um scary and threw them off track a little bit so I um I think if I ran it again I would want to incorporate some more milestones maybe not weighted but just so that at the start they can latch on something and run with it um for continuity I would rather than having sequential projects I would nest them um so that when content wise leads into the next so that there's a bit more of an investment in the project and then lastly um and these two things are kind of intertwined I would rebalance the time so instead of the first one being two weeks and the second being seven I would make the two week one longer so that they have time to assimilate the skills that they've just learned and the seven week one shorter so that it prevents monotony um and those things should be easier if it's all the same content too so that's all I have to say about that and as I'm new to teaching I would love to hear your feedback on these things that I'm saying at the Q&A later and if anybody wants any more information about the students I have some business cards too thank you


We'll start with a project overview. So CEL is a £6 million five-year EPSRC project, and we've got another 18 months or so left. UCL is leading a consortium of eight partners up at their logos there at the bottom. And their aim is to provide an energy data resource for the UK research community. So that means providing high-quality smart meter and link contextual data for innovative research in the public interest. So we are recruiting and collecting data for around 8,000 to 10,000 households in GB. And we're aimed to be representative of the SMETs to populations, so people with second-generation smart meters. So you're probably aware, high-resolution smart meter data could be a real game changer for research. But there are substantial barriers at present to getting access for researchers. So you've got the technical barriers of actually accessing that data, the legal barriers around the sensitivity to the data, and then the financial costs of getting access. So to counter this, CEL is providing a central resource for the UK research community. So we're already funded. You don't have to pay for individual access to the data. We're providing a secure lab environment. So a smart meter data is personal data. So we've got this virtual environment you can work in. Our UK data service team has overcome the technical barriers to actually accessing the data from individual meters. We provide data linking at the household level. And what I'll mainly talk today is about the observatory data set. So this is the data set of the 8 to 10,000 households, and that is for study on its own, or to act as a control group for your projects. And we're also going to be providing a laboratory function where researchers can recruit their own participants and we'll be able to access their smart meter data for you if you have consent. So so far, we've recruited around half of our participants and we're currently in our final wave of recruitment, so letters went out last week. And we're aiming to reach hopefully 10,000 in the next couple of months. We are open for business. So we've got a UK DS study number 8666, which you can search on the UK DS website, check out all our documentation and some code. And research has already begun. So we have researchers using the data now in the secure environment. So to give you an overview of the different data sets we're using. So there's electricity data and gas data from the smart meters. We've also got weather data, the survey and energy performance certificates. And this combines into what we're calling the CERN Observatory data. So the electricity data is daily and half-hour readings. In theory, all participants should have this. We also have export data if it's available. So if someone has solar panels, we get them their export data. And that's active and reactive power. When people sign up, so they can, they give us consent to access their data and we can go back up to 12 months depending on when they moved into the house and when they got a smart meter. The gas data is quite similar. So again, daily and half-hour readings, but not so many people have a gas mains meter. So that's 70% of our solar participants. The weather data is from the ECMWF and it's irrefiberated analysis data. So modeled based on readings. It's publicly available and hourly resolution 30 kilometers spatially. Initially we just were providing surface temperature but in the next data release we'll be providing up to 920 more areas. And that's a little bit behind the other data sets because it's released quarterly. Now, when people sign up to sell, we ask them to optionally fill in a survey. So that's about 40 questions about the dwelling, your participants and their attitudes and behaviors. And pretty much everybody at least starts the survey and most people are completed. And that's just one-off connection. And finally, EPC, which you might be familiar with, about half of the phones in the UK have an EPC. So we source that externally and it's publicly available but we link all of these data sets together. So now we're going to a little bit more detail about the data you can expect. So we collect the smart way to data via something called the DCC gateway. So that's a messaging service and that sends us the data directly from each household meter. We get the electricity and the available gas data in half hour in daily readings. We also get inventory data. So basic information about the meter although we're not currently making that available for researchers in UKDS, but something potentially for the future. So our team at UKDS collect readings every single day and we then make them available in UKDS approximately quarterly in terms of the files you can expect. So there's daily and half hourly files. So these are reads for each participant for each day and for each half hour with the available energy data. We also create a retype summary table. So for each type of reading for each participant there's the amount of data available with each type of error flag that we've created and some basic re-statistics of the moon and the max. We also creating a participant summary table. So that's a high-level data quality summary for each participant. So that includes non-smart reader data and basic info. And I should say that the energy data includes both the raw data and these error flags we've created and some basic error collection if possible. In terms of the different retypes available. So this table shows you all the different retypes for the daily and the half hourly data. There's some example values in units. And you can find this table and a lot more information in the documentation we've created which is on the UKDS website with the study. I'll just say a few things about the sensitivity of smart reader data. So consumers own their own smart reader data. It's personal data. So we write to participants and get their explicit consent for collecting the half hourly and daily smart reader data. And that's going forward until they withdraw consent or move out I don't have a stated end date for that. And then as I said before historically back up to a year if possible. So most of our data goes back to around 2019 a few of the earliest readings from August 2018. And as we'll talk about later all projects need to have ethics applicable from the university and be approved by the cell data governance board. So the cell survey is answered online or on paper. It's about 40 questions and it's optional. It's mostly multiple choice and then there are some derived variables that we've added in some. So things like the number of adults and the number of people in each age category. And we've also included some error flags and some basic data cleaning. Here's, this gives you an example of the types of questions we've asked. A copy of the survey can also be found on the UKDS website, the study. So things about energy and heating including the heating practices time changes to energy efficiency. Information about the accommodation but the number of rooms when we think it was built. And things about the household and specifically the household at the end. So how they're managing financially if they've got an electric vehicle and they're working status. And then the energy performance certificate data is the publicly available dataset. It's about 80 variables and about a half of our participants have that data. So it's a mixture of practical data for things like the energy rating, energy. And then numerical data like the total flow area in the square. The weather data, as I mentioned before it's publicly available and it gets updated every three months. So it's a re-analysis model of climate data. It's an even space locations, 30 kilometers apart. And in the datasets, each participant has a grid cell variable to link with their nearest data point. So we can do that. And we're moving from one variable to around 20 extra variables in the next data release which will be in a couple of weeks time. So a few things about the data governance board I mentioned earlier. So UCL is the data controller for cell data. The data governance board of the DGB is formed of independent experts. So from industry, government, academia and consumer interest groups. So it's independent from the team at UCL and from cell. So they acted the data owner to review and approve data access requests. And UCL acts as the DGB secretariat and we have a technical advisory role. So in order to access the data it will require accredited researchers, it's only available to UK University employees, legal reasons and access is always within the secure virtual lab environment. To give you an idea of some of the projects we're planning or we started, we've got one project on the COVID-19 impact on energy consumption to see how lockdowns have impacted how people are consuming energy. We've got a project about smart EPCs. So how smartly to data can enhance energy performance certificates or provide a different alternative in use energy performance certificate. And then we'll also be producing an annual report to report on some of our smaller projects in general findings from the data. We're going to be linking cell with the English Housing Survey, hopefully recruiting some of their participants to match up their EHS data with our cell data. Some of our consortium partners have got projects as well. So for example, Leeds Beckett have a project characterizing building thermal response to understand the time spent in thermal discomfort as people wait for their homes to heat up in winter. And it's out hunting that researching habitual energy consumption over periods of weeks and months in order to understand the potential for peak demand shifting. So that gets you a flavor of some of the projects we've envisioned and I'm sure that will be far more that you might be interested in doing. So if you'd like more detail, we've got our website and email address for inquiries. If you'd like to subscribe to our newsletter to get updates about the project. And of course, you can check out the UKDS website with that study number there. So far we just have the conference paper about cell, but we'll be producing a few more publications this year about how the data is collected and the data descriptor.


So in this series of mine just on deep learning for people who are interested in deep learning Perhaps more specifically for medical personnel health care personnel people involved in health care want to solve problems in Health care using deep learning just making these first these couple of videos just to Get behind some of the mathematics now I have a short video just on linear algebra, which is very important in deep learning and this one is just going to be on derivatives derivatives Here we go Now if it sounds like the world is coming to an end our right outside my office here They're building a new neuroscience center and of the last couple of months. That's already well. It's driving me insane There we go. So derivatives are very important. We're going to have this Concept in deep learning called back propagation and that really depends on derivatives I want you to relax though. You don't actually have to do these derivatives You're gonna write a line of code and the computer is going to do the derivatives for you You should have some basic concept and if you haven't done calculus in a long time This is it now I do have two very large playlists on YouTube one on linear algebra and one on Multivariable calculus and I'll link them below if you're really interested you can have a look at those 100 100 more than 100 videos more than a hundred videos really if you want to get Really deep into into the topic. I've got those playlists for you Let's do a few short minutes just on derivatives Now, let's imagine an equation. I have y equals x squared and that's it. Oh, let's make it plus four X squared plus four. So if we have this it's going to be something like this And that's going to be four and we have this nice X squared plus four remember behind the scenes There's another x here, but it's to the power zero anything to the power zero is just one and four times one It's just four and remember how? Derivatives work must have had seen derivatives at school if I have x to the power n This is just simple and if I take dy dx Or dy dx is one way to write it why prime you might have seen I bring that in forward and I take one away from the exponent So if this was why is x squared y prime is going to be bring that in which is now to forward That's x and I'd subtract one from it. That means one. That's 2x And the same this is exactly what we have having y prime is going to be two times x And if I bring the zero forward that's zero times four zero zero times anything is zero So if we have a constant the derivative of a constant is zero it is gone Okay, so if I have something like y equals 3x squared plus 2x plus five I have that dy dx is going to be equal bring that forward two times three six Subtract one from that. So there's just one left bring the one forward two times one. It's just two and There's a one day one minus one is zero So there's zero left at the top anything to the power zero is just one so two times one is just one So it's two x six x plus two is that derivative Now, let me just clean the board Now that's pretty simple if I have a single variable, but what if I have two variables We usually write that as z and let's have z equals six x squared plus four x y plus three y squared Now I have two and how am I going to take a derivative of this if I look This will be in three dimensions and we usually have this as the x y plane and that's orthogonal to each other So you can think that's in the corner of the room and here we have z So we're going to have that this thing. I can't draw that but imagine it is just going to be this Three-dimensional thing in space is not going to look like that believe me But just imagine now what we need to do in the algebra is we're going to the system has to learn certain values And it has to learn those values and the way that it learns it is it writes a Multivariable equation like this now some neural networks. We're going to write and they're going to have more than a million Parameters more than a million of these x y z ABC there's any 26 but imagine we carry on and there's over a million So it's going to be this equation of over a million and it's also going to eventually you could if we had access to so many Dimensions imagine a million dimensional space, but it will be some convoluted shape in this multi-dimensional space And what we really want is the minimum We're in this now. This is very easy at two dimensions Where is this whole multi-dimensional thing at its minimum? And then when it's at that minimum, that's the point we after all the values of x y z all those millions of parameters if I had a value for each of them and So that that whole equation which is some graph in multi-dimensional space is at its lowest point at its minimum That is the value that a deep learning network is is after if it gets that it has the best values to answer the question We're trying to answer through deep learning So how do we get a derivative? How do we get to the lowest point? Well, if we just have One dimensional space. Let's have that we can start at any little point The derivative remember is the tangent point the point of a straight line that just touches there in three dimensional space It will be a flat plane imagine a piece of paper that just that is flat And it just touches wherever the space just in one little point, but that'll be a plane Three and four dimensional space. It'll be a hyper plane and multi-million dimensional space It'll be a very convoluted hyper plane, but it touches our graph in one point and I can use that slope To get to a point Yeah, I can There's something I can do to get to this point here and at this point the slope of That tangent line is going to be zero and the plane That lies here that touches just there is going to have this slope of zero So in one dimension as I said here in this dimensional space It's easy I have a slope and we use the slope to update to get to a new point Which will have its slope which will have a new point will has its slope And we can to change the slope change the slope change the slope until we get to a slope Very close to zero and then we know we're okay. We know that we are okay now This is easy to see but imagine a multi-dimensional space which we can't Find them in our brains You don't know where it is it's like you are in the space and you start walking blindly Now imagine blindfolding yourself and you in a place where there's a bit of a valley And you have to get to the bottom of the valley You know you can wander around until you go lower lower lower until you get to the bottom of the value of the valley And that's exactly what we're going to do. We're going to be some way and then we're going to start taking steps now Remember when we looked just well in my video if you're watching that just on the simple linear algebra for deep learning You know if I want to get to this point and I see this point as a vector What I could do is walk that way That way but I can move this one here. So that's there so to get to this point I might as well walk this way and that way so that will be so many units of x I'll walk in the x direction and so many units in the y direction if I make that walk I end up in that same place as if I went straight there and that's what we're going to do here We're going to walk in the x direction Which points downwards for us and then we're going to turn 90 degrees and walk in the y direction Along the slope that goes down and if we do those two things combined We've gone further down and the more dimensions of this you'll just have to do this in more one dimension But what we do is when I walk along the x-axis, I keep y constant I don't change on the y-axis and when I change the y-axis I state one plus in one spot on the x-axis. I see those two as constants And that's exactly what we do when we do derivatives And we write partial derivatives like this and I'm just going to take the derivative with respect to x I'm going to see y as a constant. I'm not changing on my y-axis I'm just staying straight on the x-axis. That means all the y's here are actually constants So if I do this derivative that x I can do that's going to be 12x by bringing the 2 forward Now that is a constant There's a one there I bring the one forward one times four is four The x disappears because it becomes a zero and the y is still there because it is a constant That whole thing is a constant and the derivative of a constant is zero It's gone because remember there's an x zero here if I bring the zero forward that's nothing And that is my derivative of z with respect just to x And if I do the partial derivative of z with respect to y I see x as a constant That means here's a y zero here. So that's going to disappear There's a one there. So that's going to become four x And that's going to become six y And that's going to become six y And that is those are partial derivatives and all you do with partial derivatives You keep all the others constant. So if there was also W's and v's and a's and b's and whatever in there you keep them all constant You only look at the derivative with respect to this you keep or you keep the other one constant And eventually you'll get this multidimensional pointing things And you combine all of them Do the one and the other one as you walk there and there you walk along this way then along that way And in multidimensional space if you have basis vectors that are all orthogonal Everything is going to lead you in a different direction But if you combine all of those things you at a lower point And now we've got a new point On this thing we can take a new slope Do all the same thing again and eventually we'll be lower And so we will go until we get lower and lower and lower if we just repeat We repeatedly do this And that is why we have these things called derivatives. So together with linear algebra derivatives Are very important now if this was all agreed to don't worry about it If you're interested in it watch my over 100 videos just on Multivariable calculus, it's quite interesting multivariable calculus But really you don't need that for we where we are going As if you just have some mild slight concept of what is happening here That's all that's required. We don't have to take any derivatives when we design We just have to understand that that is what the algorithm is doing It is trying to find a path That lowers the slope so that we can get to this bottom point And that in any dimensional space is what we are after because that is going to be The best values that are learned by the deep learning network to give us the most accurate solutions