 They're a great search. Brought to you by DJI and Adafruit and this week's great search is electrolytic capacitors. Everything you need to know that I can cover in about 10 minutes. Okay, so let's uh over here I've got this design I'm working on an Eagle CAD. It's got a big chunky power supply and it's got these two capacitors. Let me just zoom into the power supply so you can see where they live. So one of these capacitors is a 47 microfarad 25 volts and it sits before the 5 volt regulator. It's there's a little bit of Paris protection circuitry on off switch and here is the 24 microfarad input and it's in parallel with a 0.1 microfarad. And then over here there's actually another 10 microfarad over here to the right but this is the output it's at least 47 microfarad plus and because it's a 5 volt output I need at least 6.3 volts of a voltage rating for the capacitor and then I thought I'd show the overhead real fast what these look like. Okay so what is an electrolytic capacitor compared to your kind of standard issue ceramic capacitor because you're going to see both in many designs. So this is an electrolytic capacitor it's a metallic metal tin there's a marking showing which one's the negative side. If you're using through-hole electronics they look like this you know they come in various sizes this one's a 22 sorry 220 microfarad and this is a 1 microfarad so you know you're going to find them it's usually 0.47 oh yeah I've never really seen anything below maybe 0.22 0.47 microfarad and they'll go up to like farad you can get super capacitors so many thousands of microfarad easily billy farad up to like one farad if you get a super cap very big they're large they don't come super small I mean these are fairly small electrolytic capacitors but you know a lot of them are going to be fairly chunky they actually are round pieces of foil inside that create the capacitance and you know if you compare this board which has two to a board like this which has none right this has no electrolytic capacitors at all it has ceramic capacitors so why why do you want electrolytic on this well first off if you have the space um electrolytic capacitors for you know uh cost per capacitance you're going to get a much better deal like you know a a 10 microfarad ceramic capacitor was going to cost you maybe 10 cents um for that same price you can get something that is um you know 200 or 470 microfarads is electrolytic capacitor so you're going to get much more capacitance second um if you do need a lot of capacitance for your circuit because you have a big power supply with a lot of you know a lot of current draw an inconsistent current draw that you have to protect against with ceramic capacitors they don't like you can get 100 microfarad but you don't really see them higher than that ceramics you can see them as little as a 1.2 picofarad right they'll get as small as possible in the picofarads and up to you know 10 22 47 and maybe 100 microfarad you can get that high but they start getting expensive and they start not being as effective ceramic capacitors are highly affected by the DC voltage across them um they're very small they're great at high frequency uh work uh in use cases because um they have a low ESR but when you have a big power supply like on this board where i'm going to be like drawing a ton of current like up to an amp and it's going to be drawing servos and whatever instead of having you know 4 10 microfarad capacitors in a row which i could have instead i pick one large electrolytic it's partially a cost thing but also you know this one is a 100 microfarad uh 6 volt capacitor again you know it to to make that with ceramic capacitors you either have to pay a lot more um or you end up having a lot of capacitors in a row uh and these work wonderfully um and they're they're durable and i like them so you know they don't replace ceramics electrolytics have a have a big place if you're making very petite electronics chances are you're not going to use uh electrolytic capacitors but when size isn't an issue and uh you want to reduce costs you're going to definitely go for electrolytics so that's that's your like two minute briefer of of when you want them um okay so let's go to uh digikey.com and we can that's the the capacitor so uh you know again there's there's more than like three basic electrical basic capacitors but there's kind of basically three there's the ceramic i mentioned really good for high frequency 10 microfaradish or less is what they are best at electrolytic uh big inexpensive bulk capacitance um pair them with the ceramic and you know you got the high frequency and the low frequency uh matched up and there's 10 uh tantalum or tantalum um a lot of folks will use tantalum because they're very nice uh in between you can get very high capacitance 220 470 microfarads easily um high voltage uh rating however uh i found that they're more delicate it's a lot easier to pop them um electrolytics ceramics are non-polar electrolytics are polar but they can kind of put up with it a little bit uh tantalums will just pop instantly the the moment you abuse them uh so watch out for that and second uh you want to make sure that your tantalum is being ethically sourced if you're getting electrolytics or ceramics you don't have to worry about that as much so let's uh look for electrolytic capacitor and you know there's going to be thousands that's one of the nice thing about electrolytics is they're so generic you're going to be able to have tons of options like you you never have to really worry about like am i going to be able to find an electrolytic capacitor in stock don't worry you will it's like a resistor like they're these are plentily made um so that said uh here you go there's uh you can see there's you know two uh areas there's uh tantalum and there's uh aluminum electrolytic and we're going to go to aluminum electrolytic no you know there's about a hundred thousand of each okay so under electrolytic uh capacitors again there are a lot of options and you're going to want to very quickly narrow down because even when you get to like the one of the most you know you really narrow down you're still going to have like a hundred options so just be aware of that it's not going to be like some searches where we're like let's craft the perfect search and then one item pops out with capacitors you're going to have a lot of options no matter what so look at what's in stock what's available you know what what you care about um but you'll have a lot of options available so let's um let's first look for only active um we don't always see this but uh on capacitance because oftentimes folks are looking for a range of capacitance uh instead of like shift clicking you can have a minimum and a max so let's say i want uh 47 to 100 microfarads and i believe yeah so that automatically updated to about 11 000 options that's kind of nice tolerance um you know it depends on how much you care about this uh for some audio use cases you know you might want a tighter tolerance for bulk uh capacitance for power supply you know what's nice is that the tolerance basically is just like how much they've been them right so you'll rarely get less than 10 or 20 um negative but positive it could be over right which is something you have to think about like usually when you have a bulk capacitor for your power supply you don't care if it's twice as much you're like bonus like free like it's kind of when you open up like you're drinking it's like filled up all the way to the top and you're like nice it's like an extra sip in it you don't care as long as it isn't like halfway full um same thing with capacitors electrolytic especially they're they'll do they mass make these and they're like as long as it's not less than 47 microfarads it goes in the bin um okay so there's also uh one thing to watch for is there's you know through hole or plug type and um there's surface mount so uh chassis mount and surface mount so through hole just to show you real fast uh you know as your standard you can get axial this way these are kind of nice uh they sit nice and flat on the pcb um and then this of course like your common everyday electrolytic capacitor um you know through hole electrolytic capacitors are great i have a bin of them i do recommend picking up a bunch if you don't already have some because they're always useful for like stabilizing power supplies and new pixel leds you know you add a big capacitor nice uh nicely smooths out the power supply for you um that said i'm going to undo the mounting type because i actually want surface mount sorry okay so surface mount and then now it's like okay there's a couple different there's like a lot of different like settings that you might not care about but the one thing you'll definitely want to look at is the voltage rating um electrolytic capacitors work best when you give them at least 20 25 percent of headroom above the expected voltage you're using so if you have a 5 volt power supply um you'll want it to be uh rated for uh 6.3 volts and you'll notice like the voltage ratings are like they're like oh they are more than common rail voltages so if you have a 3.3 volt rail pick four volts 5 volt rail 6.3 volts 7 or 8 volts you know 10 16 is 12 and above 20 25 you know you basically just pick the next one up and give yourself a little headroom um for this power supply uh 12 volts in is the maximum dc input so let's pick 6 volt rating um you can always go higher right so if you can't find the capacitor you want the size you want at 16 volt just bump it up to you can always get 20 20 25 but i'm not worried about getting the right uh capacitor so i'm just going to pick 16 volts okay um so next up you see the tolerance kind of now you only have two options for tolerance that's great polarization's bipolar or polar uh bipolar means that it can be um current can go either way uh sorry the voltage the bias voltage across can be either way um current of course can go back and forth depending as long as the for unipolar as long as ground is is lower than the power rail the positive rail bipolar it doesn't matter they're actually designed so they can go either way those tend to be used for audio um i don't really see them anywhere else to be honest um but for audio dc uh blocking capacitors um that said uh you will pay more for them uh and they're pretty rare so i'm just going to get rid of that option okay and then um size and dimensions so all capacitors come in very standardized sizes which is really great uh let's go to the overhead real fast and i can measure this it's to use so uh for this capacitor i measure it uh this is five point sorry five point two ish millimeters uh this one is also five point two um but if you look they're a little bit smaller than the uh outline um when you're buying electrolytic caps the you'll pay less if they're bigger you'll pay less uh if they're wider you'll pay less if the voltage is lower and you'll pay less for a lower capacitance so more capacitance you'll pay more higher voltage rating you'll pay more smaller size you'll pay more so all things can considered you know if you're if you're concerned about costume size we'll just go with the biggest one you can uh fit on your pcb okay so you go back to the uh computer so i'm going to pick uh six point three millimeters which is the size heat uh seated height you know this may matter to you in this in my case i don't really care too much um the seated height is not that important but you'll see the majority of them are they're not all the same the diameter is more uh uh standardized than the height um and then you know now you still have quite a couple hundred of them so like what what are you going to use to differentiate well you're going to pay more for um lower ripple current so the ripple current is is you know basically tells you how much how good is it at um keeping them from being variations in current and voltage so you'll get lower noise basically this is a shortcut impedance ditto um high impedance cheaper so here like four ohms uh lower impedance you're going to get uh less ripple um ceramic uh capacitors in exchange it as a comparison have much much lower um uh impedance i think this is the same as oh sorry it's not the same as the esr sorry i'm mistaken uh although i don't know what the impedance is compared to the esr so the esr sorry the equivalent series resistance um the lower it is um the less ripple and usually the more stable your power supply is um ceramic capacitors have much much lower esr i have seen some power supply chips that require high esr for stability um for for their feedback loop um i only saw it once but like it actually made a difference the power supply chip said do not use only ceramic capacitors on the output you have to have at least one electrolytic capacitor um so you'll pay more for lower esr again um they're almost all rated at about 120 hertz but i guess some are rated at 100 kilohertz um for again for me it doesn't matter so much there's also lifetime temperature um again this is whether you are using you want something high reliability at high temperature electrolytics as people who do power supply work know they can die if they are used for a very very long time or they're poorly made or it's very hot so all these things are over liability um i'm just going to go for general purpose and then i'm actually going to like check just for the ones in stock that's 59 and then there's still a lot of options and then this is what i actually like do my little shortcut i just filter by uh sorry yeah i filter uh going down by uh quantity because uh at this point i'm like there's too many options i don't know what to pick you can do it by price but it's tough because again there's so many variables of what you're paying for um you know comparatively for the lowest like current ripple the lowest esr the lowest size so i kind of just go with like whatever's popular and um so in the end i actually thought okay this 47 micro farad 16 volt plus or minus 20 looked pretty good um you know the lifetime temperature i don't really care it's polar i know that um the ripple current was not too high 58 um milliamps and the esr is oh the esr is not rated here you have to look at the data sheet so um i will say checking out the data sheet is is going to be very helpful first off because they have like all the dimensional data and they'll also tell you all of the different um if you like the capacitor you have but you want to get one with like smaller diameter or you want to get one with a little bit more uh capacitance or better tolerance you can use the the numbering system to um figure out like how to like calculate what the part number would be that you want we see okay so it's got the ripple current is here let's see if they have the esr i think they don't i think they're just general purpose and they're like we don't really rate them they just tell you like it's probably like you know an oh maybe or something um of course you can also measure it when you get the capacitor itself but it sounds like it's not it's not guaranteed just interesting right but for general purpose this is good enough for me i'm you know i'm using this with a 7805 the 7805 is like not very picky about you know the capacitance and then i add some ceramics as well um so i ended up producing this one and i think it's going to be just fine i like uh nuchicon as a supplier i've never had any issues with them i'll say that there's a lot of suppliers i think they're all going to be equally as good but i've had very good luck with nuchicon um the entire time i've uh made electronics and so i kind of tend to use uh those are pentasonics again you know the electrolytic capacitor is a very jelly bean it doesn't really matter but if you had if i have two and one of them is pentasonic or nuchicon and one is some other brand i haven't heard of there's the two i'm going to go for so those are my electrolytic capacitor tips in the great search it's a great search for this week