#744 Measuring Capacitor Leakage (easy and cheap)

okay here's a topic that a lot of people have heard about and a lot of people have talked about and i guess it's time for me to talk about it since i always duplicate everybody else's stuff but um leakage current of capacitors so we know that old capacitors like aluminum electric lytics uh go leaky after they're after they're old and um different capacitors even when they're new some have more leakage and some have less leakage and so i want to take a look at exactly what is leakage and how is it specified what you should expect and how to test it all right so what is leakage well here is a uh electrical schematic a simplified schematic of a capacitors okay there's some inductance due to the leads and construction and everything it might be coiled up so there's some inductance and then there's some parallel plates in there that are act as the capacitor and then there might be some series resistance so it's called effective serious resistance and there might be some leakage and we can think of that as a resistor across the plates okay and so we're not talking about this we're not going to talk about this and we're not going to talk about this what we're going to do is we're going to talk about this this leakage okay what is this leakage and what can we expect all right so certain types of capacitors like ceramic capacitors are not very leaky at all and some film capacitors are very very good they're not very leaky at all electrolytic capacitors are the worst so the aluminum electric lytic capacitors you know the ones that look kind of like this these are the worst and that's due to their construction and the chemical makeup inside okay let's look at a data sheet so i pulled these off of the nichikon website so nichikon is known to build some of the best so whatever specs they have they must be good um so here is a um a capacitor that might be used in a radio um it is a uh a 400 volt capacitor and let's look at the let's look at the uh let's look at the specifications here it says ideal for low profile so it's small uh low profile power supply application so it's good for filtering power supplies all right downsize high ripple design so it's meant to meant to take out those ripples right so it has a rated voltage of 400 to 450 volts well which is it 400 or 450 why do they have two and a capacitance of 27 to 120 microfarads okay so you can get these in a various various ranges so they're in the 27 to 120 micro fruit capacitiveness range which is kind of power supply range right okay so endurance with ripple current so as ripple happens in a capacitor there's an ac voltage on the capacitor and as we know it uh polarized capacitors don't like ac so they can kind of do damage to the uh to the makeup of these things over time so this is endurance with ripple current 2 000 hours and 105 centigrade so also high temperature the chemicals don't work very good also and they degrade so this is meant to be really really really hard and robust non-solvent resistant type flux remover or something and ross compliant okay so the characteristics are there's a temperature range and it's it's looks like there's two different capacitor types one that's good from minus 40 to plus 105c at 400 volts or minus 125 to 105 c at 420 or 450 volts so a little bit confusing on what we're actually saying here they might be saying that um you get one of these and if you operate it at 400 volts then you can expect this uh temperature range minus 40 to 105 but if you operate it at 450 volts then you can then you have to uh live with minus what minus 25 instead of minus 40. all right so i could close them a little further here okay so the next thing is rated voltage uh see capacitance tolerance is plus minus 20 so it might say 100 microfarads but that's plus or minus 20 so electrolytics have a very wide range leakage current so that's what we're interested in um so how is this specified first of all it has something says cv okay so we'll talk about that so cv less than a thousand and cv greater than a thousand okay let me let me get a piece of paper all right see the less than a thousand or greater than a thousand sorry about my greater sign okay cv well i'll see these exactly capacitance capacitance and voltage voltage okay so it's capacitance times voltage c times z okay so let's say we have 100 microfarad capacitor and we're going to operate that at 400 volts okay our cv is now four zero zero zero zero okay there's four zeros uh in the micro it says here where i equals current in microamps and voltage in microfarads okay and rated voltage in volts okay so we got it right okay so the c is going to be in micro so we can get rid of our micros here so it's 100 times 400 is 4 40 000 so that's definitely greater than a thousand okay let's say you have a 10 a 10 microfarad capacitor at 16 volts then cv is only equal to 160. so that's less than a thousand right so you need to calculate it for the capacitor you've got okay and so then it says if cv is less than a thousand then the leakage current i is going to be 0.1 cv plus 40 okay and if it's greater than it's going to be .04 cv plus 100. so what does that mean well you multiply the c times the v so let's just take the case of our uh 100 microfarad well that's kind of a big thing okay let's get let's let's let's not think about that let's think about this one 10 10 microfarads at 16 volts 160 okay so we have 160 times 0.1 that's 16 plus 40 that's 56 okay and so it says that we have couldn't have up to 56 micro amps of leakage current wow that's a lot 156 microamps of leakage current okay but that's after one minute what does what does that mean after one minute well once the capacitor is charged up and you wait one minute then you measure it and then there's a thing that says after five minutes after five minutes it gets better and we'll talk about that why does it get better okay so this is this is this is the one minute category after five minutes it's .03 cv plus 15 and .02 cv plus 25. so you can see this is a much better spec than this is right so after five minutes it's this so in our case it's less than a thousand so we're gonna do uh 160 times 0.03 look at our calculator oops 160.03 is going to be 4.4.8 plus 15. so it'll be 19.8 micro amps all right so after one minute it could be 56 microamps but after five minutes it it uh it could be uh 19.8 micrograms okay that's the speck it's got to be better than this all right so that's the way it's done it's specked in these units of cv and depending on how long you wait so we didn't talk about that why does it get better why does it get better well these plates of capacitance these metallic plates have an electrolytic inside they have this this goo inside and this goo inside has charge and when you apply voltage on these plates you will start getting positive charges on one side and negative charges on the other side and then this goo in in the middle will start to migrate will actually start to move and it will align itself with either negative or positive depending on the polarity of the goo right and this is kind of why lcds work right lcd panels are are capacitors and they have goo inside and you apply a voltage on them and they change state depending on what voltage you put in them well the goo inside of capacitors actually changes around also as you as you turn them on right and so once you leave them on they start separating and there's not as many of them in contact and so you don't have a big of a leakage path when they're all jumbled up in here there's more chance of it getting through but when you turn it on for a while these things start to separate and align to their neighbors and where they want to be then there's more electrical isolation in in in the chemical and you get in you get better leakage now if you have a capacitor that's been sitting around for a long time let's say you buy some new old stock you go to your surplus store and you buy some old electric lytic capacitors and you put them on put put them on the tester you go oh my goodness they're leaky i think i have some of those so we can do this test i've never done this before but this is i know the theory um if they've been sitting around a long time then these guys uh have a tendency to be very leaky they are they're just been sitting around for a very long time they're kind of rusty all right and if you put a charge on it you can kind of get them moving again you kind of kind of get them going again and once you get them going again then they finally they finally start doing the right thing again they finally start going to the positive side on the negative side and they kind of heal themselves they're self-healing and so if you have a capacitor and you put the working voltage so this is a 400 volt capacitor you put 400 volts across it and then you wait half an hour half an hour that's a long time you wait half an hour and then you rejuvenate the capacitor i think they use a different term too you restore the capacitor they people who are into this they use some terminology for it re re oh god well i think the paper has it i think i think the paper uses the terminology i'm not i'm not uh reconditioning that's that's it they call it reconditioning all right so reconditioning your capacitor you put the voltage on it and you wait half an hour so i think we can try that because i think i've got some that are old but good all these big goodies um so how do you measure the capacitance of i'm not the capacitance uh if you want to if you want to measure path and just get yourself a capacitor meter right so i've got this nice lcr meter it'll measure capacitance it'll measure inductance and it'll measure esr it'll measure it'll measure all those good things but it won't measure leakage you need a leakage tester okay and so you can go off and you can buy a leakage duster i've got one i can show that one to you a another thing you can do is watch somebody else's youtube channel and he's got a very fancy capacitor leakage tester and you can go build his and um be happy with that um or you can just do it the way that i do it which is just trivial and why doesn't everybody just do it this way i i don't get it sometimes sometimes my mind is just too simplistic and i just i don't know i'm a simple boy so you wanna you have a capacitor okay and you wanna measure the leakage right which means you have to hook this up to a power supply so let's put a current limiting resistor in here for good safety and we'll put a plus v on it and then we will charge up that capacitor right depending on the size of that resistor that capacitor will take some time to charge right and if you wanted to measure the leakage you put in an ammeter right you want to measure microamps so what do you do you put in a microamp meter right you measure the amount of current and what range of measurement device do you need well look over here 56 microamps 19 microamps okay uh maybe one microamp you know maybe that's good enough um a tenth of a microamp but i you know i don't know that's 100 nano amps that's pretty small it sounds pretty good right so um let's go ahead and do this we will measure the leakage of the capacitor and um we will measure it a couple different ways we will use a couple different instruments to measure microamps okay okay so we want to measure microamps you get a multimeter that has a microamp a microamp scale so here is microamps okay and it looks like we can measure 0.01 microamps that's that's pretty good um one thing i didn't mention was when you measure the leakage of a capacitor that's specified at full working voltage so this one we're going to measure this this capacitor here ignore that over there that's just some 5.5 stuff this is a 220 microfarad at 16 volts so we want to test it at 16 volts it will have the worst leakage at 16 volts and the leakage less than 16 volts will be a whole bunch better okay so we want to measure at 16 volts and so what do we do well that little diagram i said we're going to put it through a current limiting resistor here's a 10k so we'll hook uh 16 volts up to the top of the 16k okay and oh that's my meter that's the wrong wire this wire here is 16 volts all right and uh okay so this is going to be the ground side but we need to go through the meter right so we're going to put the current meter here so the so the voltage comes in the top 16 volts goes through the resistor goes to the capacitor and then comes out the bottom and that's going to go through the meter to ground okay and here's our ground okay so let's watch the meter when i hook it up and it's starting out at 400 microamps okay now remember what our spec said our specs said after one minute and after five minutes well guess what we're gonna have to wait and um so um yeah uh we just have to wait so um you might have a tester and it might have leds and those leds go ding ding ding ding ding well it's just a volt meter those leds are just a voltmeter it's just using it's just a voltmeter it's all it's all it is just a voltmeter it's just measuring the voltage across the resistor that's all that thing does anyway so here our little leds are going blink blink blink and we're just watching it so you know why why build something i mean i already have this right i already got it and we're here at one one you know it's less it's certainly less than a minute already and we're certainly at one one microgram well it's weigh in spec right it's way way in spec it looks great and it's still getting better right so yeah we can wait we can wait until it finally asymptotes to some number or we can just call it a day and say yeah it's fine right yeah it's fine um so um like i said there's suddenly some self healing going on so that one minute spec and that five minutes back if we wait five minutes um you know that's what we're watching we're watching that that that that chemical start to separate inside those capacitor plates and um and heal right there's an exchange of ions and yeah fancy chemistry so there we go it's currently a slow down point anyway so this meter's working great right point eight point eight two point eight one point yeah so it's doing great so okay done so you can stop watching this video now because because you know everything you need to know this is this is all you need to know okay so i'm going to prove to you that you do not need fancy equipment all right you you do not need fancy equipment um we're going to use something that's maybe more affordable um here harbor freight i got this for free they actually give them away once in a while on a rare day i don't know if they do anymore but i remember on a rare day i think i got this for free it was one of those come in and buy something and get it for free anyway it is a free multimeter and i think there are probably five dollars new i don't know um but guess what it's got a 200 microamp range it actually is a microammeter so that's pretty cool so let's go ahead and we'll hook up the positive side here and we'll hook up the negative side over here and let's go ahead and short out our capacitor so we start from start from zero again okay we'll use this uh we'll use this piece of wire here as a as a short we will short it out here to the positive side here anyway so that's kind of going okay so now we will hook up our current meter again and we'll watch it there we go as before uh this is the 200 volt range it's a little it's a little high there we go 100 so it's doing exactly the the same as the 60 meter right um so there we go it's going down it's going down to going down and i claim once it gets below a microamp it's like well why are you looking any longer you know why are you wasting your day so yeah so there you go right five bucks done do not build yourself a capacitance duster it seems silly to me now you might want to build yourself a high voltage supply then you could test your 400 volt capacitors at 400 volts so that's a good thing to do some people build their supply and they build a current meter into it so they can do this test but i don't i don't know why you want to dedicate everything just for a capacitance test all you need is voltage and and a microammeter and and that's all you have and like i said you can get these you can get these pretty cheap you can get these really really cheap um so 0.6 microamps right and this thing's this thing's not bad it you know it's certainly within 10 you know and that's fine it's all you need so there you go there's your there's your fancy dancy um microgram meter all right so um certainly there are other things that people might be worried about that might be more finicky than i am so i'm not bad mouth anybody but it's just it seems like people spent a lot of effort in in capacitance testing that just doesn't seem to be necessary so let's talk about um let's talk about a little bit more now remember um it's this leakage right so we're talking about um we're talking about 0.6 uh 0.6 microamps at 16 volts okay so what resistance is that let's calculate that all right so we have 16 volts and 0.6 microamps is 26 mega ohms okay equals 26 meg ohms okay so so if we wanted to test our test our fancy meter here well we can do that easily with a resistor if you happen to have one now not everybody's going to have these resistors so you know this thing's good within 10 percent right absolutely for sure but i have some high value resistors here that are just laying around so let me grab one here uh let me grab oh that one's too high uh that one's too high that one's too hot here we go so here's here's a capacitor this is a hundred meg ohms okay 100 meg ohms so 100 meghams let's do the math we love math right everybody loves meth um 100 mega ohms okay times 16 volts or 16 volts divided by that what would tell us how much current with that right so 16 volts we should get 160 nano amps with this .16 nano amps right if we put this across to 16 volt 16 volts so here's our 16 volts we'll put that here um well we can start we can start here sure why not um let's see if we can measure 100 meg ohms with this thing okay so there point two so certainly within ten percent right point two it should be point one six but it's point two so we can measure a hundred meg ohms then let's try our fancy meter because they had one extra digit all right so where did i put the clip leads here there so microamps microamps 100 megaohm okay so there you go 0.15 perfect 0.16 even better okay so uh so if you were going to build your own capacitor tester and you didn't have a micro amp meter you only had a volt meter then you would measure the voltage across a very large resistor does that make sense and you would calibrate it so that a certain voltage across this fancy resistor was either pass or fail okay so that's the way a lot of these good passenger testers are made they're just made with a very large um 100 mega ohm 20 mega ohm 82 meg ohm whatever you want it whatever you want to call it you can get a big megome right and then you have a capacitor tester all right so let's so that was what that was 0.16 0.16 all right uh here oops sorry here here is an 800 mega ohm resistor 800 what is that 0.02 yeah 0.02 so how do i do that math it's 16 volts and eight right so it's 0.02 um so there you go so this meter works just fine up to 800 meg ohms it probably it's its last digit is it is at a gig ohm right so this will measure gigome resistances now you tell me you tell me is there anything that you've ever built that would care if your capacitor had a gig ohm resistor across it okay think about that is there anything you've ever built okay i can only think of one instance and that is a microphone preamp um and that's a pretty special case but maybe there's others i mean people in audio land like are just nuts i mean they they believe in crazy stuff you know oxygen freak uh yeah anyway i don't want to go into that but some people are very very picky and they want the best and maybe a gigan is just too much for them but a good a gig i don't care i really really really don't care about any good one all right let's uh let's take a look at a a piece of test equipment that's meant to do just this and we will measure a capacitor that i believe is an old stock might be on the bad side and then we can see if we can what do they call it rejuven not rejuvenating uh re i've not forgotten again please remind me reconditioning um reconditioned that capacitor and see if it gets better so um let's do that okay sorry if i'm ranting i do like to rant don't i um but i'm of the philosophies keep keep it simple right um if you haven't watched this channel actually enjoy it um keep it simple stupid guy kiss kiss analog anyway let's see uh let me look at this these these are old new stock that i got at the junk store i believe and i bought them because they're high voltage they are um they are 100 volt so this is 10 10 microfarads at 100 volts okay so let's measure the uh let's measure the leakage here um i'll measure as high as i can with this setup put this uh put this in circuit and we'll hook up our micro ammeter and we will set our volt meter as high as it can go as high as it can go i'm using my uh hy1803 28 volts let's use 28 volts all right that's as much as i can go here so um okay so we've got 28 volts coming in and we're looking at the microamps and then let's turn it on and all right so let's watch is that in camera yeah okay all right we're about one minute so at one minute we're about uh 30 microamps and maybe 30 micrograms is just uh not your thing maybe you just don't like 30 micrograms so let's go ahead and uh let's go ahead and and uh i'm going to charge this thing directly with uh the 28 volts i i don't have a 100 i'm just putting 28 on it and i put it directly across the capacitor so now i'm just putting voltage on that capacitor i'm just putting it there and we'll we'll wait a couple minutes and come back and and see if uh yeah see if it gets better there is a memory effect a recharging effect also in electrolytics that g that confuses issues sometimes but they're both related uh the the rejuvenation thing is uh the chemicals when the chemicals go to the plates and then they they pull apart and then when you let go they move back again and and the act of moving back they can actually generate voltage and the voltage starts ramping up again even though there's nothing attached suddenly the capacitor has more voltage in it well there's energy stored in the chemicals and that gets released into charge so okay i did that just for a short period of time i just wanted to see if you know if it gets better or not um let's see if we can find a uh let's see if we can find a volt a power supply that'll go uh we'll go to 100 volts and we can and we can test this thing better all right i pulled up my trusty 8212 a power supply i think it goes to 100 volts the scale goes to 100 volts um we'll see if it we'll see if it gets there so i'm starting off here around uh around the same around 28 of 28 volts that's kind of where we left over last time and you know we're still we're still going down right we're at 9.8 microamps but let's uh let's ramp the voltage up and you can see look at that the capacitor got a whole lot worse with increased voltage right because we're having to charge it now and you know so we need to test it at the appropriate appropriate level here so we're gonna we're gonna go up as high as it can so it does it does reach 100 volts so there we are 100 volts and we are at 800 microamps so that's why you want to test these things at voltage um so let's let this thing charge up all right um it's been about a minute um so let's let's look at that spec again uh this this is this is not the data sheet for that capacitor but let's say let's say it was this is a 100 microfarad no 100 volt 10 microfarad okay so that's a cv of a thousand right so we have a cv of a thousand and our spec is let's say the five minute spec is point zero three okay so we have a thousand times .03 so that's 30 and we have plus 15 so that's 45. so it has to be below 45 microamps to meet spec we're meeting spec right um and it's still going down so you can wait as long as you want if it makes you feel good but um yeah i don't care especially for a uh a filter capacitor i'm more worried about esr for filter capacitors than anything else so you know there's there's all kinds of different capacitors and tandulums have really really good esrs but they're temperature sensitive there we go anyway this is going to be a very very boring video of us watching the grass grow here but that that's exactly why capacitors do what they do and you don't need fancy equipment um you know it may be that you don't have a 100 volt power supply laying on your bench and uh or if you wanted it like if i wanted right now to test a 400 volt capacitor well i don't this doesn't go to 400 volts now i do have something i mean obviously i have something that'll go to 400 volts but um uh yeah so i think the the rule really is um to measure them at the voltage that they're rated if you can't use the highest voltage you can get away with and then cross your fingers if you believe testing 100 volt capacitor at 30 volts is enough then good for you um and i don't have the experience to say that one way or the other i don't know whether that's a fine thing to do and you extrapolate you can say that it should be 10 times better at 30 volts than at 100 volts or only twice as good at 30 volts and at 100 volts i don't have that experience so i can't talk it to it but i can in this particular case know once and for all at 100 volts 10 microfarad it is 11 microamps of leakage current i do know that for a fact and like i said uh 100 volts uh and 11 micro amps is 9 meg ohms right so 9 mic ohms and a power supply circuit yeah looks good to me now i know a lot of times the numbers are just used to measure whether things are going to go bad or not in the near future and that's something i also don't have a good good gut feel for like like instead of it being 10 micro amps which i'm sure is perfectly good if it was measuring you know 40 microamps um which is still within spec still within spec but 40 microamps i would feel maybe that's a bit too high and maybe i come back a month from now or a year from now that 40 microamps turns into 400 micrograms you know i i don't know how these things die i don't know how close you can be to the spec i really don't know that information but i do know you know easy ways to test capacitors now there was a youtube channel that i saw the other day when i was kind of researching this for the video where the guy had the world's best and cheapest micro current capacitor leakage tester it was just it was the best thing i ever saw instead of using a microamp meter he just stuck in a blue led that's all he did he put a blue led right here in the negative side and the blue leds are super sensitive with low current at a micro amp in a dark room you can still see it glowing right and so his tester was just one led and it was bright that's bad and it was dim that's good and that's all there was to it um it was great it was just wonderful i i i wish i wish i could remember where where i saw that but i just thought yep that guy that guy gets it um this is my this is my answer to his one diode this is my cheapy harbor freight one yeah this one works fine too all right i don't get many opportunities to pull this thing out but this is the day because we can use the leakage test this has a leakage test in it so this is my zm11u and it has capacitance tests in it so let's go ahead and open it all right let's plug it in all right so uh i have a whole series of videos on this thing so if you're interested in uh in this instrument it is a zm-11 slash u you can search uh youtube and you'll find a bunch of my videos uh uh on this instrument it's an lcr meter uh and a bunch of other things so it'll test transformers it'll test insulation resistance which is really the um like if you're measuring a ceramic dye a ceramic capacitor you're really measuring the resistance of the insulation that's really the measurement you're making and this will this will go up to uh 10 000 mega ohms so 10 gig ohms this will measure up to 10 gigahertz so we could use that to test capacitors too i never thought about that but yeah we could see if we could test a capacitor at 10 meg ohms 10 gig ohms all right so capacitors there is a c there's a c charge we're going to want c charge because we're going to test the voltage uh we're going to go to dc volts uh let's see maximum voltage control is this all right so we can set this to 100 volts this will go to 500 volts so you can test the 400 volt capacitors in here just easy we're going to set this at 100 volts but let's go ahead and get our resistor that resistor where you go that hundred here it is all right so we have this 100 volt 10 microfarad capacitor all right so let's insert that with the voltage off so i don't zap myself in fact let me turn this off so this is safe safety safety third right isn't that what mike rowe says safety third okay so now we have our 10 microfarad in there and we can turn it on and charge it we can take it up to uh oops knob we can take it up to 100 volts let's go let's go to here uh we can measure its value uh with the with the capacitance meter right here and measuring nine microfarads that's what that's what this says nine microfarads anyway that's a different thing we want to measure leakage okay so the way you measure leakage is with the ammeter and we will set dc volts to off and we will then turn this knob yeah it's this knob here okay so let me um let me let's get this up so we can get a good camera angle on it this is going to be hard remove the camera okay so the capacitors on the test where it says c uh we're in uh high voltage mode so i shouldn't put my fingers on here but this is 100 volts and the way i test that is i go here to volts and i'm measuring on the volt scale at the top so it's 100 volts and so we go here we'll turn that that voltage off so we're not measuring voltage anymore and then i'm gonna start turning this knob and i'll turn it to here and we can read the dial now this is the milliamps this is leakage this is it's going to measure the current that's going through that capacitor and it has three different settings uh uh 25 milliamps full scale five milliamps full scale and one milliamp full scale so one milliamp full scale is a thousand microfarad of a thousand microamps full scale right all right so we'll go to we'll go to five and we see we see that needle not moving at all so if you're testing a bad capacitor like a really leaky waxy or something like that in here and you turn it if you immediately get 25 milliamps you stop and you don't go any farther right you know that's bad so you can go to the next stop this is spring loaded you can't leave it in that position you have to hold your hand on it so here's five milliamps and we look for the meter deflection i don't see any then we go to one and i don't see any meter deflection at all so that's the way they were tested in the old days that the one milliamp scale was fine and dandy you didn't need anything fancier than that it was ready to go um so this is measuring um a full scale is a thousand is one milliamp or a thousand microamps and it's just not deflecting the scale at all so yeah it's just not it's not measuring anything here right so um but we are testing it at uh at voltage which is nice and we can test the capacitance at the voltage also the way that i i didn't really show that on camera easily the way that i tested uh the way that i tested capacitance was with a bridge circuit so i change this knob here and this knob here so this is range okay so this is a 0.1 millifar microfarads micro micro was m in the middle base of 0.1 and this is uh and then this is 1 and this is 10. so those are multipliers so okay so this is in this position it's one micro farad increments or multipliers for the scale okay so then we look at the uh let me turn the room lights off we look at the seeing eye tube and the seeing eye tube gets uh the 65 uh gets wider and white and whiter and then it gets narrower again right at the end here and so i set it just for uh there and then i can change this a bit let's see yeah this is going to be a little bit like here okay that's a little bit better a little bit finer so what i'm doing is i'm changing the key the d value on the bridge there we go so you can see it now um it gets it gets wide and gets crispy and then it gets blurry again and you want it right at the wide crispy spot and it's right there and it is 9.1 microfarads so there you go um you couldn't see that could you because all room lights were off so what i was doing was i was adjusting this knob and making it crispy and the way that i got it a little crispier than it started out with was to change this knob and this is the d value the circuit the circuit tries to mimic the capacitor you've got right so you put in an unknown and you're balancing it in a bridge with a known which is here and if all your varying is capacitance it doesn't match the inductance and esr and other things inside and you need to to balance that on the other side to make the two exactly the same so it has this value here d which allows you to adjust the resistance on the other side and add some series resistance i think is what's going on here and then you can make this a little bit crisper and then you turn this knob until you get maximum deflection and then you read to a 9.1 off the scale here and you multiply it by one and you get 9.1 microfarad so that's the way that works okay so i hope i showed you how to measure leaky capacitors and i'm no expert at making them good again the rejuvenation process but i couldn't find any that were bad enough to try to rejuvenate but i've seen lots of people do it online and they they seem to think it does something it does make sense the uh the chemistry of uh the electrolyte that's inside these things it does seem like you know if you have a an old battery maybe you can recharge it a bit and it'll last a little bit longer probably won't last a long time but it it'll give you uh maybe a little bit longer life it's like taking a non-rechargeable battery and charging it you know not a really good idea but it actually does work a little bit i think anyway there you go

Channel: IMSAI Guy

Views: 21,181

Keywords: s100, s-100, cpm, cp/m, cpm80, intel 8080, 8080, 8085, zilog z80, vintage computer, vintage computing, IMSAI, IMSAI 8080, ALTAIRTTL CPU, cpu design, eagle cad, eagle pcb, 8-bit CPU, 8bit CPU, diy cpu, 74181, 74381, 74382, ALUZeta, Zeta2, ROMWBW, Zeta SBCelectronic test equipment, vintage electronics, DIY electronics, electrical engineering, electronic engineering, electronics, PCB design, Circuit design

Id: H1qMV_hTGGw

Length: 47min 4sec (2824 seconds)

Published: Thu Mar 25 2021