Power Conditioning with Energy Harvesters – III

i showed you a demonstration of the thermoelectric generator by applying it on my body and i also in fact on the hot side i just rub the little bit to create a little more ah you know a little more heat and we measured it went to quite a significant ah higher voltage so what does it mean it means that the body heat and the ambient if you are able to get some temperature differential hm you will get reasonably good power output ok how does it compare with a photovoltaic systems well in terms of power density i would say ah thermoelectric generators are even thirty to fifty times higher ok but then lot of paraphernalia circuit and lot of ah adjustments have to be done to get the thermoelectric generator to actually work and give you something useful nevertheless if you find a nice application then this is the best place this is the best kind of ah energy harvester to actually try out your circuit let us think of some some kind of a nice application one thing is let us say you are interested in finding out you have your household geyser right and for some reason assume that you have access to some ah you know some part where the ah water ok the water that is ah getting you know getting heated inside your access to that temperature ok you are able to access the the place where the system is you can feel the heat right then i mean its a little bit hypothetical at this stage ah inlet is cool outlet is ah you have hot water you have stored in the geyser if you are able to harvest this this temperature that is one side of the teg you ah connect it to you as essentially interface it to see the one that we had in our hand here you have hot side yeah so this is the hot side one side is the hot and the other is the cold so as you know as thick as this if you are able to do that then you could use that to measure certain critical parameters of the geyser itself for instance the temperature of the water itself can be measured by a putting a temperature sensor right so you take the teg you take the teg ok and then you connect it to some piece of electronics you piece connected to some electronics ok what you should get will be a v out let us say i like this three point three volts because it seems to be more and more standard ah and you get ground so you connect this to some system which essentially has the ah thermistor let us say let me write it neatly t h thermistor right s t e r i think it is yeah ah so this is essentially yeah thermistor which is connected to ah some sort of let us say an s o c and ah which also has some communication ability and the microcontroller and of course this is connecter some a d c port right and this teg is like a power supply for this so as long as you have temperature differential ah which is let us say room temperature you will have let us says twenty five degree celsius and water is boiling and it is even going up to let us say fifty degrees ok and you are able to keep this surface in contact with that you perhaps have a nice way to harvest because you now have a temperature differential which is d t essentially ok some people even say ah yeah they use this word d t which is a very important ah which is then so it is a temperature difference differential ok difference some temperature ah ah so that if you are able to maintain

is something like twenty five in this case you will get sufficiently good amount of power ah which you can harvest the question is how much power everybody keeps worried is in fact this is the question that you will have to keep how much power do we get what can we do with that ok so this is i think i am sure is prime in your mind ah its all good but can you what can you do surely you will be able to drive this thermistor ah directly without any battery or anything with this electronics ah this is basically power conditioning electronics like this is the power electronics i will say power electronics and using this power electronics this gives you this table output voltage and then you should be able to do continuously you should be able to sense comfortably it should work if you are able to maintain this temperature difference ah in a sustained manner the real challenge is dear friends how do you maintain this temperature differential continuously it appears that what i said is a very nice solution provided you can actually pull it off the cold side it is insufficient if you keep it at ambient right when you say ambient you cant get away by keeping it at ambient because very soon the hot side heat flow because you have a flow of heat from the hot side to the cold side you will attend this fifty quickly back here this is going to create a problem for you therefore dear friends it is insufficient to maintain it at twenty five degrees ambient instead you may have to keep it in contact with the water flow pipe right so you have a water pipe and and outside of the water pipe you will have to keep this cold side the hot side should the other side the other side which is the ah thing one that should be in touch with the ah ah place where you can tap into the ah the surface over which the water is the hot water is actually in contact with then you will be able to harvest and keep this sustain but if there is no water flowing and you just want to keep it in ambient i dont think it will work ok so this is the very interesting thing another ah this is the very important thing so maintaining this temperature difference is the key please note because very soon heat flow ah is indeed an issue all of this means in physics terms the right what does it mean it simply means everything about thermal resistance thermal resistance if you have a low thermal resistance you have this problem in fact tegs really have this problem that the thermal resistance is pretty low and its also so this is one part so you much keep this you must bear this in mind that ah because of thermal resistance change in thermal resistance you will have to ensure that this temperature differential is maintained ah in a sustained manner you must look up the data sheets look up data sheets which will allow you to ah which you will give you some specifications on the thermal resistance of this ah particular teg that you have so but as electrical engineers it is just not about thermal resistance but it is also about the electrical resistance right electrical resistance of the teg that you are int interested which is nothing but the source resistance source resistance also called the source resistance i will put down some numbers from the teg that we used the hot side if it is maintained at forty ok and the cold side is maintained at thirty celsius you will get a voltage at match load ok which will be about zero point two volts that is two hundred millivolts ok n and current you will get zero point zero four five amps that means you will get forty five milliamps ok and so this is the volt spec this is the current spec and this is

the most important thing will be match load will be match load will be four point five ohms ok this is a number given by the manufacturer i am not inventing anything here second if t h is sixty t c cold side is at thirty degree celsius ok you will get ah a voltage the match load voltage voltage at match load will be zero point six volts and current will be amps will be zero point one one amps ok ah a hundred and ten milliampers and the match load ok i should write it here because match load just to be consistent match load is ah fifty five point two ohms so you can see as the temperature differential ah difference in temperature here it is ten ah and here it is thirty right you get higher voltage and higher current ah also the match load resistance we will continuously keep increasing so the teg that we ah this particular specification of the teg you may be interested in knowing is from a company called t e c i bought this from t e c and this particular teg is indeed t e g ah two slash a two dash one two six l d t for body and sensor power thermo electric electric harvesting applications so ah in this design for i o t course you may have an idea of designing a variable right and you may be wondering if i design a variable i will have put a battery definitely you will have to put one ah one option is it put a battery because if it is measuring a critical parameter you cant be a hunting for ah temperature differences when you are actually measuring that parameter you will put a battery this ah teg can be used for charging the battery continuously wherever a temperature difference whenever temperature differentials are available you should be able to harvest from that and then from that you should be able to keep charging the battery so its a nice solution indeed which you can seriously consider to if you are trying to build at the end of you know going through this ah this ah you know with these inputs that we are discussing at this stage ok so the take that we have is a forty ah cross forty mm cross five point four five ah mm ok all the is is actually you can see its just a little over half a centimeter thick and it has a forty cross forty four centimeter cross four centimeter ah into a a thickness of about five five about half a centimeter five point four five m m and it is a good teg indeed and you as you can see it seems to be giving reasonably good output voltage ah from directly from the ah you know from the ambient maintaining the ambient if you are in an a c room surely temperature will be at thirty six and ambient will be at ah around twenty or even twenty two depending on comfort level so you should get a clear safe ah ten degree differential ok delta t will be about ten ah ten and with that you should be able to get reasonable amount of power from what we have seen this from this specification so this is the story of the teg and ah so how did we go about a power conditioning this teg and what is the story behind this teg

with respect to ah you know understanding the kind of numbers that people talk about in terms of power output and this particular power condition and power electronics that is associated let us revisit that picture and then let us see ah to put everything back into place so for that what i will do i will go back to this picture right we started with this ah l t c three one zero nine as you can see the teg of interest has been discussed the one that we purchased and we were trying this power electronic part is this l t c three one zero nine this is a one is to hundred transformer we will discuss that in a moment and we also mentioned about source resistance which is which has to be as low as possible ah and and then we talk about a microcontroller read you and all that ah and of course what is important is ah you see now we got a body sensor right body ah body heat harvesting sensor which i wrote here the here i had written about the fact that this has a application for body sensor right so this if a body is a body and sensor power ah applications ok this one hm essentially what we were doing is ah so this is a very nice ah ah you know energy harvester alright what is the correct ah power electronics ah that you should choose ok because this company t e c has not indicated any specific ah company that we should use any vendor particular vendor ah chip energy harvesting chip for harvesting to use ah to be chosen so we were investigating this in the process we found that this l t c three one zero one seems to be an appropriate one so let’s put down that we have an l t c three one zero nine this is l t c three one zero nine ah ah d c d c of course everything around what we discussed in till now has already been that we are talking about boost converters and nicely this boost converts often give you an l d o output as well apart from the actual v out and they also give you a something called a v store right and v store is meant for applications where some amount of energy stored in the v store is pumped into vs v out during the time and the input harvest it is not there for some reason if the harvester is absent ah the energy for a very short duration from v store goes to ah v out here ah with respect to this particular teg of interest that we are we are we are talking about as i mention to you this is forty mm and this is forty mm as well i cant show you thickness on this thing but imagine that it is thick enough which is five point four five mm and that has to be connected to something we have mentioned is the one is to hundred ah step up transformer ok here there are some design considerations and we will discuss that in a as we go along ah when to choose one is hundred when to choose one is to twenty for instance and one to choose when to choose one is fifty for instance its quite obvious right so you would if your input ah is typically of the order of thirty millivolt that means just coming from body sensors then you have to choose one is to hundred if your input is more than this lets say its fifty millivolt and so on fifty or sixty millivolt then you dont need this kind of one is two hundred step up so you could choose one is to twenty and accordingly if the voltage goes up you can choose one is to ah one is to ah so sorry one is to fifty and then one is to twenties also are possibilities as this input voltage goes up now when will the input voltages go up depends on your application right the geyser application i mentioned is giving you a good amount of temperature differential in which case you will perhaps not need a one is to hundred you will be able to get away ah even sometimes you may even be able to get away without any transformer directly interface it to l t c three one zero five which is good for us in some situations if the volt so you have to actually find out what is your harvesting opportunity in terms of the temperature differential find out that then choose this particular transformer ok that is the key to what i am trying to ah get it now ah the problem with

this teg is this this particular teg is that ah you must i must put this downright i will put it down in capitals heat sinking you must do heat sinking there is no other way the cold side should be able to with i mean draw the ah the heat which is emanating from the ah hot side it should be able to pull out that heat otherwise temperature differentials will go down and then ah nothing will come so you have to look at how to design ah a good heat sinking ability for this ah for this system ok ah so there will be ah ah some sort of data sheets ah there will be a data sheet which will tell you so you must go back to your data sheet and carefully look at what are those data what is it that the curves in the data sheet are actually telling you ah about the current ability ah for different input voltages and different ah turns ratios so this transformer again is the issue so you must ah ah look at ah so that is the that is the most important thing so you must look at temperature differential so i will say d capital t one then input output everything input voltage ah ah input ah showing output current capability for different input voltages right so input voltage output current all of that should be essentially coming up to you from the data sheet ok so ah so that is the most important thing in general hm you can say you will get fifteen milli from watt the manufacturer is claiming you will get about fifteen milliwatt ah at the output in terms of power output you will get about fifteen milliwatt of output ah maximum and the minimum you will get this is maximum and then this also we will be about the minimum will be roughly about ah fifty micro watt this will be the minimum power ok so that is ah another important thing now question is ah whether you will get continuous power is the question continuous power o u continue o u s continuous power well i dont think ah you will get continuous power ok if you if you are able to keep the ah temperature differential for long time for for in a sustain manner why not surely you will get but in practice that will be a little bit difficult ok now you will have to also battle several things on why did you choose this ah teg in the first place i mention to you that the data sheet did talk about ah the fact that it is meant for body ah heat harvesting and for body sensor and all that but i could have chosen ah other some other vendor also right and from that so they may be a similar product from other vendors well hm so the question really is like this right ah it will the basically depend on the average power for the given application so the question really is about the d t so the question is about d t is the is the key and the application average power is so d t and average power see these are the two important things you will have to ah worry about ah again the ah the the manufacturer gives a lot of nice numbers i would like to stick to what the manufacturer is saying ah rather than speculating anything from my experience on working with teg because that i have looked at several tegs and i think you should just go by ah by looking at the data sheets studying it carefully around the data sheet you should be able to plan your design what the ah manufacturer is actually claiming

is that ok he talks in terms of the manufacturer is actually talking about ah if you take a ah you get an output power the output power of a typical teg of a typical teg hm is roughly ah ninety microwatt per degree kelvin for every one square centimeter of teg area this what it simply means is this means that you are maintaining ah ah good heat sink that is very important i am not when taking that taking that into ah ah into any account but what is usable it turns out that this what you will get output power of the teg is this what you will get but if you do all this l t c three one zero nine conditioning one is to hundred and ultimately what is important is this v out right what is it that you will get it v out and the i out the the current and voltage out at the output if you see they claim the manufacturer make some nice observation he says you wont get this so i will strike this off this is input if this is the input what you will get will be twenty five microwatt per degree kelvin for every square centimeter area of a typical teg ok ah that is what you will get so if you take forty mm cross forty mm ok that is your area hat you have ah with the d t of let’s say ten degrees ten degree kelvin right ten degree ah ah with the ten degree kelvin across we will give you roughly four milliwatt will give you about four milliwatt ok so thats a good enough power in my opinion with all the low power electronics that we have ah so this is reasonable right you should be able to use this four milliwatt power in a very effective manner with some good power management algorithm this is a good number i would say this is the very good number to work on ok so do look at the manufacturers data sheets carefully and go ahead with the design ok so here the point is that ah we have assumed source resistance to be two point five ohms of source resistance that is the key point the source resistance assumed will be three point ah to sorry two five ohms so which is also another important consideration the ah energy harvesting applications energy harvesting applications using ah tegs you will obviously choose a teg this is the very trivial answer right maximum output voltage and maximum output current you will want to go and buy that teg which gives you the maximum ah power ah ah maximum power output right so this also means ah obviously with lowest source resistance this is always the nice thing please note maximum [laughter] output voltage maximum output current and lowest source resistance the smallest the smaller it is the ah very good thing it ah good for the system to give a good amount of power output ah they also mention that larger tegs larger size tegs like what we are discussing about forty mm cross forty mm this is the pretty large size teg the four centimeter cross four centimeter we will also have ah lower hm thermal resistance we will also have a lower thermal resistance indeed a pain right this is a problem so you are heat sinking should be very good because very soon the hot side and the cold side we will come into an equilibrium because of this lower thermal resistance problem so heat sink you have to thats why i said the

geyser example looks a little shaky at the moment but automobile maybe good you have the radiating radiator ah some coolant and some circulation of or even if the vehicle is moving the ah the engine surface can be hot ah wherever you have placed the teg ah but because of circulating air the cold side may continue to remain at some reasonable point and that can be definitely in an automobile ah ah you know in the engine compartment part of the automobile that its very possible that you should be able to harvest hm significant amount of high power from that system also this tegs a meant for this kind of very high temperature ah applications hot side can really go to high temperatures so again you will have to choose based on your application you may have to choose what kind of temperatures this tegs can which stand also note that you should not reverse the hot and cold side cold side cannot which stand high temperatures so if you touch the cold side on to the engine side which is emanating lot of heat then you may actually the teg may actually go bad and may not be able to you may not be use it so take care of this simple precautions before you start you know using it in a particular application let me complete the story so this low thermal resistance has an issue and therefore which means you will have to put good amount of ah heat sink sorry heat sink s i n k becomes definitely a critical requirement for hm ah for this but if you are using large teg which means area is of no constraint to you putting a heat sink is also not an issue right if you have if you have sufficiently large area i would not recommend ah way tegs for body based systems but at the moment they seem to be the only ones which can give you sufficiently good power that is the issue so you may even want to examine ah small ah tiny ah nano pelts or micro pelts micro pelts in fact there is a company called micropelt just google it you will find a company called micropelt here the source imp ah source resistance of these ah systems hm is roughly i think my from a memory two hundred ohms or something like two to three hundred ohms see what it all of this is leading to something very interesting right ah if you have higher source resistance to begin with the output voltage that you will get from the teg will be high that is clear ok whereas if you take the lower heat this lower source resistance tegs like to ohms two point five ohms five ohms and all that the output voltage will be in the order of a few hundreds of millivolts tens and hundreds of millivolts i would say tens hundreds of millivolt so you dont even have to worry so much about ah if you first thing that you can look up in a data sheet is what is the output voltage let us says he says thirty millivolt fifty millivolt i can give you fifty millivolt i have a circuit for fifty millivolt to give you three point three using power electronics and all that or if you says i will give you a two hundred millivolt or hundred millivolt and so on first thing to infer straight away is its source resistance must be in the order of a few hundreds of ohms two hundred to three hundred ohms this is very clear first first i would say hm rough first cut ah understanding why why i am stressing this why i am stressing this i am stressing this because your choice of power electronic chip become very critical here you take the wrong ah power electronic vendor chip for a thermoelectric application and connect it you get nothing in other words this source resistance should match the input resistance of the chip right for instance if you take this teg that we are discussing from this company called t e c tec and connect it to the same vendor some other chip ah which is also energy harvesting chip is an incorrect decision i will give you what the vendor himself says he says if you take my teg my ah my chip my chip three one zero nine l t c three one zero

nine or three one zero eight ah i assume i assume the source resistance inputs or the source resistance kind of tegs that are going to be connected or the order of two point five ohms to five ohms because he is on load load resistance is around this and unless the load resistance the load resistance and the source resistance these are not matched if they are not matched you have serious ah you know extracting you have serious problems of extracting any useful power from that system keep this picture in mind that is why your design is has to your choice of component become very critical ok so micro pelt is another company i mentioned to you whose source resistance which is in the order of two hundred to three hundred ohms dont choose this l t c three one zero nine or three one zero eight choose some other one what he recommends on the micro pelt website is from this vendor from the chip from this vendor t i which is b q two double five zero four or he even suggests ah the ah l t c you can also use l t c three one zero five with m p p c we already discussed this so with m p p c ah you can use l t c three one zero five or you can interface it to b q two double five zero four remember whatever you do you have a beautiful tool in your hand and dont forget to use the tool and what is the tool simulation tool right every vendor will have a simulation tool you just have to look out for it if you choose a component from ah vendor a look for a tool from vendor a it will be there in fact b q has a simulation tool for this b q chip ah the once that we spent a little time trying to show you ah the this vendor linear technologies has has his tool typically l t c spice you go to some other company they will have a tool them even have an online tool simulation tool which is you feed in values and then you will get some ah you know system design related part numbers and components of your of that would be required for taking up your circuit so lot of system design challenges building the i o t system is in become start becoming very comfortable if you know where to find things and how to do things thats all i am trying to say ok ah for instance if you say this is my input voltage and this all i can harvest from the environment and the differential that i am able to maintain feed in those values it will actually tell you what kind of components would be required do you have to put a one is to hundred should you put a one is to fifty should you put a one is to twenty ah step up transformer what are the other components what should be the inductor value for instance output inductor value because dont forget this is a buck con this is a ah boost converter right ah so either boost or buck the output inductor is an critical thing here so that will be ah will definitely be there so let me draw your attention to the simulation tool for l t c three one zero nine we can discuss that i can show you the simulation and then ah please download and try it yourself if you dont have a teg it doesnt matter right you have a p c or a laptop you have any internet connection download the tools which are available dont be sold to any specific vendor all vendors donot exam in different vendors and then try and mix match change make changes to the simulation parameters based on the models given by the vendor or closest to what the vendor provides run your simulation once you are satisfied then go about investing ah to by ah these kits or components to design your circuit so that part is something you will have to look up just now so let me turn my attention to this nice simulation ah which i have done on for ah piece spice so this is the l t e spice l t e three one zero nine you can see that this top side wherever i have pointed my cursor this top side essentially is the ah transformer which has been used i did not make changes to this circuit which i also

found on the web so lets not waste much time i will expect you that i expect that you will be able to ah modify whatever is available here and then start ah you know and actually ah try out ah do a hands on by this yourself so you see now from zero volts the output is slowly picking up and this simulation will run for a while and you can essentially try everything that you want you can modify parameters i will just stop it here so that we can spend a little moment or to ah here so you essentially can change parameters you can change the output capacitance you can change the transformer you can change the kind of source that you are looking at and then re simulate the circuit and before you actually prototype anything so what is important is to really run this thoroughly before you ah finally use it so this is in summary a big summary of all that was required ah with respect to a use of thermo thermal energy ah with ah when you talk about energy harvesting for the the power section of the ah ah embedded system or the i o t system that we plan to ah we actually will plan to built two points two points come up ah to summarize or you know to further ah you know to further let us say ah you know sort of consolidate our learning on use of tegs is one thing that come up is can i use tegs for charging a battery the answer is yes but you should be careful that ah you should actually pass the output of the teg into the power management or battery charging i c of the battery so in other words you have the v out coming from the from the boost converter ah of the ah lets say l t c three one zero nine or boost converter chip ah and this one should actually go through the battery charging chip and then it should connect to the battery this will take care of all the over voltage and under voltage protection ah which will ensure it because particularly if you are if you are charging a lithium ion battery then you obviously we will have to connect ah a temperature sensor right so it will be connected to the temperature sensor because you dont want to charge in the battery ah during charging with the battery gets very very hot there is a chance that this might even explode so lithium is an explosive so you have to take care and use all possible precautions to ensure that ah the charging is safe so you should not directly ah you know charge that that is another important thing second thing that occurs is what is the ah ah efficiency of this system typically i would say it is anywhere between in tegs if you are using the efficiency can be anywhere between twenty and forty pa ah forty percentage unlike solar which is you know people say even solar theoretical efficiency ah about with efficiency on paper is twenty six percent most panels dont give you that kind of efficiencies and the discussion i did with respect to solar after all the conversion and all the losses and taking care of all the climate a weather changes i have just taken ten percent and i give you those numbers with respect to ten percentage quite like that in the teg world people do claim that it is in the order of twenty to forty percent ah but there are there is not include all the losses losses are not included so i let you ah judge for yourself based on several of these things ah before you decide the actual ah efficiency of the system

let us now move on to another type of let us now make a clean slate right so i will rub this and i will make a clean slate let us know talk about another type of energy harvester right harvester and as usual let us begin with the demonstration of this energy harvester ah then we will see ah how this ah the what kind of applications this particular energy harvester actually has ah madhuri my colleague here we will actually demonstrate another type of harvester and what she is actually going to do is ah you will see that there is a nice enclosure this enclosure is is made out of three d its a three d printed enclosure and its a three d printed enclosure here and you will see carefully that there is a plunger here there is something though like a press which she can actuate and she will press that in a moment and what you will see is if she process that plunger ah essentially its like a switch right ah you will see this mechanism inside getting also depressed and a certain amount of voltage being generated ok so let her adjust the time base such that you will be able to capture a nice ah system what she actually has in here hand is nothing but electromagnetic switch basically linear motion harvester you can call it so a linear motion of this plunger there is a coil and and there is a magnet inside of course and every time she presses there is a small amount of ah voltage that is induced across this coil and it is just essentially a source of energy for the ah system as you can see this can be used in many applications where ah one can ah can you please that again yes so you can see that the systems can be used for ah essentially ah you know pressing ah for harvesting energy for using them as push button switches ok so this is essentially a electromagnetic switch ah which is harvesting energy from kinetic a kinetic energy harvester which essentially ah is a source of power ah to to power in applications where push buttons ah push buttons are required where should we ah so what is this what is this is this is this the actual so what you do with that kind of way form that you get thats an a c waveform right obviously you have to hm build a small circuit around this push button switch so lets develop that circuit also and see what actually happens at the output of the this kind of a harvester what you will have to do is so this is a linear motion harvester ok this harvester is a essentially i will represented like a block and i will have to connect it to a bridge rectifier bridge rectifier ah and output can be stored in a small capacitor here ok what i have used is a thirty three microfarad capacitor to store our energy and what i have used here are bat fifty four diodes these are schottky diodes schottky barrier diodes and very effective for this kind of energy harvesting applications essentially these are s c h o t t k y schottky diodes meant for energy harvesting applications

ah this diodes these diodes is schottky diodes ah have you had to note several things about these diodes basically there volt forward voltage drop forward voltage drop is dependent on the forward current essentially if the forward current is something like ah point one milliamperes the forward voltage drop is two hundred and forty millivolts and if the forward current the current drawn through the diode goes up to hundred milliamperes then you will have a forward voltage drop of about eight millivolts again i draw your attention to the data sheet please look up the data sheet design everything around the data sheet this is the key point ok so and in fact the data sheet we will tell you nicely ah all these data in fact all these numbers that i am putting out here or actually from data sheets right so the whole design can if you have the idea right ah rest of the thing can actually come out from the data sheet itself alright so here is the linear harvester linear harvester which is basically an electromagnetic switch this is from a company called cherry you can use it from cherry is called the cherry switch we can also use eco two hundred from enoceon enoceon this is another company which were by which you can buy this kind of a linear harvesters use them put them through a bridge rectifier circuit ah and essentially ah store that energy and use this energy how much we will you get again the same question right we think from our calculations we get about hundred and twenty micro joules of energy you are getting about maximum of about hundred and twenty micro joules of energy and what can you do with this kind of micro joules of energy well you will be surprised that you can do several nice things first thing you can do is you can boot the microcontroller you can boot the microcontroller you can sense on the a d c a d c port and and you can also ah transmit a b l e bluetooth low energy data packet thats all that you can do right and this is already good enough suppose you want to send an on or an off you want to sense a position of a switch you can do all of this with this little small harvester how does the d c output look that is the next question right because a c ok you have to do all that power conditioning and all that let me know draw your attention to the ah d c output ah so for that let us look at the the ah d c output coming from i have taken a snapshot of the ah the d c output so let me show you how that looks this is how the ah the output actually looks you can see that ah this is one volt per division so it is going up to a quite a high extent of about three point three volts or so its able to go go to ah to roughly three volts plus and remains there for this one point ah one point eight milliseconds of time ah and after which it is so this time from this point here to this point here is already good enough for you to boot the microcontroller to sense the a d c and also to do a transmission of a data packet so now you see the trick you must have your crystal or crystal oscillator should come up very fast it should give you a stable clock out in microseconds macro controller should run at a clock frequency should be quiet fast

a d c conversion time should be very fast and you should be able to do quick communication to the b l e link b l e over whatever s p i i two c communication puts and also do a transmission of a data packet very tight time budget you just harvest on the fly do a transmission on the fly and be done right this is the challenge and you should be able to write software embedded software which can essentially run all this in the given limited time of about one point seven to one point eight milliseconds or even two milliseconds ah after which there is no more energy right so this is what software code will have to do ah the magic for you to ensure that you manage the power effectively