I recently took apart an old stereo reciever that didnt work anymore. As always, I salvaged as much stuff as I could, and came across 2 huge capacitors. They are each about the size of a C- batery,and are rated at 50v, 6800 uF. I, of course, saved them, but now I cant think of anything to do with them!if anyone has any ideas, please let me know stat.

Posted by tigerdog330 10 years ago | last reply 10 years ago

about capacitors

I understand that capacitors store electricity, but what controls them. what lets them discharge?

Posted by kendallickes 9 years ago | last reply 7 years ago

Help for Replacement capacitor ? Answered

250v185j cl21 capacitor  burned from  old portable rechargeable fan what can i do.. pls help me for  replacement capacitor in india

Asked by RaviT120 1 year ago | last reply 1 year ago

Do capacitors have positive and negative terminals?

What are electrolytic capacitors? In what way they are different from normal capacitors? The charge on a capacitor depends on how i connect it to battery,but electrolytic capacitors have one long and short terminal to differentiate between positive and negative terminal. Why?

Asked by deepakmurali 6 years ago | last reply 6 years ago

Replacing capacitors with different rating? Answered

Hi! I am trying to repair a computer has 2 capacitors that are blown. I have a replacement for the first one, but not for the second one.... My question: On the capacitor it says 330μF 25V, can I replace it with another type of capacitor? Wich number is important, the "μF" or the "V"?

Asked by Fypsigon 7 years ago | last reply 7 years ago

Replacing capacitors with different rating? Answered

Hi! I am trying to repair a computer has 2 capacitors that are blown. I have a replacement for the first one, but not for the second one.... My question: On the capacitor it says 330μF 25V, can I replace it with another type of capacitor? Wich number is important, the "μF" or the "V"?

Asked by Fypsigon 7 years ago | last reply 7 years ago


How come capactors are used so much in electronics for exampel: what are those 2 capacitor doing?

Asked by Balls of Kevlar 7 years ago | last reply 7 years ago

Help me connecting capacitors???

Friends i need help in connecting capacitors to get a burst of current in following cases:- capacitors of same V but different uF(i know thats not a 'u' but i dont know how to type it) capacitors of same V and  uF capacitors of different V but same uF.                                                                                & also if you can suggest me a book, article,instructable ect. so i could do it next time on my own. And i know how capacitor works but just want to know how to practically use them.                                               

Asked by Atul009 5 years ago | last reply 5 years ago

Need Capcitors

I Need Capacitors Bad!!! Any Size.

Posted by wolf996 6 years ago | last reply 6 years ago

curious about Capacitors ! Answered

M just curious about capacitors that the voltage they store when they get charged i have two capacitors laying around for test  on one is written 400v 22uf other is 420v 100uf so how much voltage can they hold when they get charged fully ??? and any simple way to charge them ??? i want make something for shocking pranks.... :D

Asked by D3zire 4 years ago | last reply 4 years ago

Big Capacitors

I found a big capacitor in a floor cleaner...I think. It is a black cylinder with two leads off the end. In the floor cleaner, it was hooked up to a lot of stuff in a really important looking box that had a lot of wires flying everywhere. It looks sort of like the thing below, but a little smaller. So, really, there are two questions: 1. Is it a capacitor? 2. If it is, what can I do with it? Thank you!

Posted by basementhacker 5 years ago | last reply 5 years ago

Is my understanding of capacitors correct? Answered

I am currently working on a "Tutorial Tuesdays" video for my YT channel about capacitors covering some of the basic theory, real-world ratings and considerations, and maybe some cool demonstrations with how to use them and stuff. I just want to make sure that I do understand them correctly,so hopefully you smarter people out there can tell me if I am wrong in any way. 1) A capacitor stores energy in a electric field between two electrically insulated conductive plates, the strength of which will depend on the proximity and surface area of the plates, the dielectric constant. 2) Can I compare "electric charge" to mass; "voltage" to density; and "capacitance" to volume as an analogy? (yes, I know I am ignoring dielectric constants and strengths.) 3) If I look at the peak to peak AC current through a capacitor, and the peak to peak AC voltage, can compare the ratio of the two figures to figure out capacitive reactance? (example: If I have one volt peak to peak AC applied across a capacitor, and I see 10mA of current peak to peak, does that mean the inductive reactance is 100 ohms?) 4) Are the most important things to keep in mind with capacitors in general are "working voltage" (the maximum voltage a cap can withstand), "capacitance" (how much charge a capacitor can store for some given voltage)  "ESR" Equivalent Series Resistance, which is how 'good' the capacitor is, and "temperature" (which can potentially adversely affect the performance and ratings of a capacitor)? 5)Uses for capacitors include Energy storage, analog filters, DC removal, voltage transient suppression, voltage smoothing, timing/counting AC coupling, data storage, phase shifting, motor starting, etc. 6) The ---| |---- symbol represents a generic non-polarized capacitor      The ---| (---- or --[] []-- (with one box colored in) symbol represents polarized capacitors    The ---|/|---- symbol (with a slash in the middle being a slanted arrow) represents variably capacitors 7) Should I try to learn how to work with complex impedance (capacitors, resistors, and inductors in all sorts of weird configurations) Also, can I treat reactance in general as a resistance when looking at capacitors in series or parallel with resistive loads and stuff?

Asked by -max- 2 years ago | last reply 2 years ago

Can substitute 300uf 450v with 3300uf 450v?

I'm replacing some capacitors on my plasma tv couse it stopped working I opened it up and these capacitors look a little bit bulgy just a bit I'm hopping if I change them it might start working again the two capacitors are hard to find so I am trying to replace 300uf 450v with a 3300uf 450v can it be done

Asked by DieslV 1 year ago | last reply 1 year ago

Help with some noise filtering? Answered

I've attached a file of a project I will build, but should I need some noise filtering capacitors? Thanks, BoK

Asked by Balls of Kevlar 6 years ago | last reply 6 years ago

follow-up capacitor Q's ? Answered

I am amazed at all the great responses I got with my last question, thank you all! :D Though now I have a few more: 7) Should I try to learn how to work with complex impedance (capacitors, resistors, and inductors in all sorts of weird configurations) Also, can I treat reactance in general as a resistance when looking at capacitors in series or parallel with resistive loads and stuff? For example, can I simply add up Xc, Xi, and R for a total impedance? Or do I have to worry about phase shifts and stuff?  8) Is it OK to say that "Q" or charge is a more theoretical physics concept and is not too important with practical electronics? (C, V, and I being more of the focus and "ignoring" Q is OK?) 9) I have added a few of the "slides" and sneak-peaks to my upcoming video. If anything is wrong don't hesitate to nitpick and point it out! 10) capacitor fall under 2 major categories, polarized and nonpolarized. 10a) [under the 'polarized' branch] Electrolytic and tantalum capacitors are used for bulk filtering, but are evil and do not tolerate overloads particularly well. Especially tantalums. They tend to be available in huge capacitances, but can be "leaky" and have high ESR and series inductance. 10b) [under nonpolarized branch] Ceramic capacitors are the most common type of capacitors, and come in a few types. Generally used for local decoupling. They are pretty robust and tolerate overloads. Film capacitors find more use in high voltage applications, have lower leakage, better high frequency performance, and certain types have self-healing properties allowing them to tolerate overloads and surges the best. Mica capacitors are generally the most stable, with the lowest leakages, so they find uses for more critical analog applications.

Asked by -max- 2 years ago | last reply 2 years ago

Capacitor quick question: (Dissipation factor vs ESR?)

I want a decent small capacitor that is suitable for "high power resonant circuits." On the osciloscope, the waveform looks like 2 well rounded humps, one that is skinny and tall and one shortly following that is shorter but longer, and this is periodic at 30KHz. UPDATE: looking at the waveform closer, it is clearly a damped ringing that is a bit trimmed. The screenshot is uploaded. The maximum measured slew rate was about 25.5MV/S, (which is 25.5V/uS, right?) for a "perfect" 1uF capacitor, that is a peak current of 25.5A! I am unsure of the RMS current due to the non-sinusoidal nature of this waveform. But it must be pretty high as well, explaining why my 3, 1cm diameter 3cm long 0.47uF MMC film capacitors get pretty warm.   . Why do some film capacitor datasheets only give dissipation factor ratings at a few test frequencies (like 10KHz and 100KHz) and others give ESR ratings as well? . Based on what I googled, I figured out dissipation factor is the ratio of ESR to the capacitive reactance. And since the frequency and capacitance is given it is not hard to calculate the ESR. So then why is this not conveniently already listed on the datasheet? Is it because the dissipation factor is what is directly measured? (like the total measured impedance of the capacitor at a certain test frequency)

Asked by -max- 2 years ago | last reply 2 years ago

Best way to accurately measure capacitance w/ osciloscope?

I am sure there are many ways to measure capacitance w/ an oscilloscope, and one of the annoying things is that some capacitors have different capacitance at different voltages and test frequencies. My original idea was to use the RC time constant and a known resistor, but I think this is probably the least accurate way to do this. Would using a sine wave function generator and figuring out capacitive reactance (and capacitance) be the better method? OR what about measuring resonant frequency of a LC tank circuit? Or some other method I have not mentioned? What's the best?

Asked by -max- 2 years ago | last reply 2 years ago

How do you know if a capacitor is finished charging to its full potential capacidence?

How do you know if a capacitor is finished charging to its full potential? Also if you were to have a group of capacitors linked together in a series or parallel fashion how could you determine whether or not the capacitors were charged completely? I am mainly referring to polarized capacitors. 

Asked by Dr. Kreap 6 years ago | last reply 6 years ago

Anyone have any capacitors laying around?

Hey, I'm doing some electrical engineering projects and I need some capacitors. Anything flash-capacitor-ish sized or bigger is best. Thanks, Ben

Posted by Ben Mighall 6 years ago | last reply 6 years ago

Quick coilgun Capacitor question

Im using chargers to rank 330V or even 370V. Heres my options. 400V 330uF Capacitor 450V 150uF Capacitor Im guessing the 330uF, But what's better for a coilgun? (using 4 of them in parallel, yet buying 10.)

Posted by Killa-X 10 years ago | last reply 10 years ago

microwave oven capacitors for sale

I have some microwave oven capacitors and  transformers that I would like to trade or sale. Iam interested in radio parts ( crystal head phones, vacume tubes ect.) I just don't have money for shipping

Posted by inductionheat! 9 years ago | last reply 7 years ago

Can any body identifie the Capacitor

I have a DVD play I'm trying to fix I found the Capacitor blow out. Can any body tell me what the spec are on this Cap. All the info on the cap in on the first Pic's the second pic' is a pic of the cap.

Posted by Bernie777 2 years ago | last reply 2 years ago

If I have two identical capacitors and I connected them in series/parallel what would happen? Answered

Take 10,000uF and 100v, Does that double the voltage or the capacitance? I want to end up with a capacitor bank of around 400v with a capacitance of minimum 8,000uF. So what I'm getting at is what can i change around in terms of capacitors and to what effect. Thanks : DBTW, I'm going for a coilgun hereEDIT:Also, if i'm building a capacitor bank for a coilgun, would i be going for the max capacitance or the max voltage?

Asked by pyroten 9 years ago | last reply 9 years ago

Can I modify an electric gas lighter to charge to charge HV capacitors?

I need help for charging High voltage capacitors. I have an electric gas lighter and I require help to modify it so that I can charge High voltage capacitors for coilgun using it.Please help me.Thanx in advance

Asked by Jayvis Vineet Gonsalves 9 years ago | last reply 8 years ago

Is it possible to run a 1.5 volt motor off of standard capacitors? Answered

I'm new to electricity and would like to make a small vehicle that uses capacitors to power a small motor (described above.) Would this work at all? are there resistors or anything that I would need? and if this could work, what types of capacitors would I use. the vehicle needs to move about 7.5 meters.

Asked by I am Bob 9 years ago | last reply 9 years ago

On capacitors and polarity.

(Asked twice already, but for some reason was not visible.) That is sort of a blanket question. I'm wondering: 1) why only some, and not all or none? 2) what (in their physical structure) causes them to have polarity? 3) why do we make ones that have polarity? Is there something prohibitive, like cost, or safety, making it so in the production? (okay, not safety, as may attest anyone who has seen a reversed capacitor explode.)

Asked by V-Man737 9 years ago | last reply 9 years ago

What kind of SCR would I need for a coilgun with 2500uf 500vdc capacitors? Answered

Using a bank of 6 capacitors, all rated for 500 WVDC and 2500 uF. I'm only going to be mainly using them with 240 and 130 VDC. Would a 500Amp SCR be applicable?

Asked by Mudbud 5 years ago | last reply 5 years ago


I am trying to turn 3v dc into 300v dc to charge some capacitors I plan to use to make a coil gun. Any way I can do this cheaply and relatively easily would be a huge help!

Posted by J55862 10 years ago | last reply 10 years ago

Charging camera flash capacitors from mains supply

Hi everyone, I have a quick question about charging some capacitors.  I'm trying to make a very simple ignition system using capacitors from disposable camera flash circuits.  I'm planning on using maybe 5 or so.  They are rated at 330V and 120uF.  If I were to hook them up in parallel, so that i have a total of ~600uF, could I use a full-wave bridge recifier diode to turn the AC into DC and simply charge it like that without anything else in the circuit.  I don't know how to explain this very well so I attatched a schematic so you can see what I'm talking about.  Any help is much appreciated.. P.S. Ignore the fact that the full-wave rectifier looks messed up, doesn't have a f-w r symbol.  Thanks again!

Posted by BCSTechie 5 years ago | last reply 5 years ago

is there an easy way to measure the weber stength of a magnet?

Have been given the task of creating a circuit powered by a rotating magnet in a copper coil that will charge a capacitor long enough to light an LED for 600 seconds after the rotating magnet has stopped. In all the magnet charge up torches I've opened, there are two 3V Lithium Cells (CR 2032) between the generator and the circuit. These cells aren't rechargable. The current from the generator is AC. I know this shouldn't be too difficult, but can't figure out how to approach it with so many unknown variables. Just looking for any help possible for value of capacitor or resistor. Thanks for any help!

Asked by 9 years ago | last reply 9 years ago

How much Joule does a coilgun need?

So I always wanted a coilgun but in germany there arent any stores that give away used cameras with flash for free because they all send them away whole to a factory for development. I recently bought a pack of random capacitors for 2,50€ and now im asking myself if the capacitors in it are enough. There are many different caps in it but the biggest  are : one 63V 1000µF and six 100V 100µF.  The single big one has a power of 1.985 J and the six small ones a power of 3 J together. I dont want a gun to kill people but i still want it to shoot and penetrate paper and stuff like that. So how much Joule do i need for the gun to work properly

Asked by Milou151 3 years ago | last reply 3 years ago

how to charge a capaticor from this camera circuit?

I got this camera circuit from an old underwater camera.It also had a motor.

Asked by ilevitskiy 6 years ago | last reply 6 years ago


Hi there. While testing some code on three servos using my picaxe 18m2 project board I initially had them powered of the 4x1.5v battery pack. This was working smooth enough, but because I eventually plan to power seven servos (for a robot arm project) I thought I'd try using a 7.5v wall transformer but they didn't seem to like this as the smoothness of movement was gone as they slowed and sped up and were jittery.  Is the 7.5 a bit much, a few resistors maybe? Or prehaps capacitors would smooth things out. I'm not overly electronically gifted, robot builders guide is all I've got to go on. cheers. john. 

Posted by jonnymelon 5 years ago | last reply 5 years ago

Please I need to build a passive infrared occupancy sensor. I need help please.

Great community, my supervisor actually want me to develop a passive infrared occupancy sensor from the scratch, I want this great community to help me the components that I will need, the physics of the circuits,  the block and circuit diagram and possibly, if anyone has an idea of what could serve as a reference for me to work with. Great community of scientists, thank you so much.

Asked by Joebaba 6 years ago | last reply 6 years ago

what is the number printed in this capacitor ? Answered

Hi i got a circuit with a 100n capacitor can any one tell me what should be the number written on the ceramic capacitor ? i think it showld be 104 but i am not confirm. please tell me!

Asked by ubdussamad 5 years ago | last reply 5 years ago

Myler Capacitor for Tesla coil? Answered Is this good for a SGTC? im using a flyback transformer powered  with ZVS driver running of 30v. So im thinking of putting 60 of these is series and nothing in parallel. The secondary is 16inch long and 4 inch dia. Flat primary with 7 turns.

Asked by jasshopper 2 years ago | last reply 2 years ago

Shorting Capacitors? Answered

Hi Guys, Recently I found a person selling a power supply for $3 and I thought why not to buy it and salvage the components. I was wondering will it be safe to short the huge capacitors in the power supply? Thanks :)

Asked by The Prickly Potato 3 years ago | last reply 3 years ago

How to get the value of these capacitors?

Hello, I got these three capacitors  there are several codes written on them but i can't find a way to find the capacitance they carry in micro farrad can anyone tell me how to read there value?

Asked by ubdussamad 5 years ago | last reply 5 years ago

help i need information on capacitors

This is a call for help I need all the basic information on using capacitors. Especially how to charge them, and discharge them. I need to know so I can post my first Instructable.

Posted by pgd5000 9 years ago | last reply 9 years ago

Can i use different capacitance values of capacitors for a voltage multiplier?

Question says it all

Asked by ARJOON 7 years ago | last reply 7 years ago

Good values for a beginner capacitor assortment? Answered

Working at my desk, I realized I need a nice restock for my parts- I have a lot of resistors on order (pretty much the Radioshack assortment but cheaper), but I need capacitors. I dont know a whole lot of electronics, so I dont know what values are common and widely used- so I need to know what values would be good in a large capacitor assortment (Values anywhere from nf to 4700uf are available where I am ordering.. so a good large assortment) Thanks! -Astroboy907

Asked by astroboy907 7 years ago | last reply 7 years ago

I need capacitor help? Answered

I have an issue with some bad capacitors and I have read conflicting information on the matter and hope someone can help me. I have 2 different caps that have to be replaced one is 10v 1500 microfarad and the other is 6.3v 1500 microfarad. First can I use the capacitors that are all silver in color with no plastic sheating (not sure of the name; pics included) because I have a bunch that are 6.3v 1500 microfarad? As for the other capacitor I do not have that exact value, I have 10v in 1000 microfarad, 1200 microfarad, and 2200 microfarad, but I have one that is 16v 1500 microfarad, what I'm mostly wondering is what can be changed the voltage or the capacitance? And would one of those work for the 10v 1500 microfarad capacitor I need or should I just ebay it? Due to a postal strike I may not get it for a while and like most I needed it fixed yesterday. I am fairly new to trying to learn electronics and hope someone can shed some light on my problem.

Asked by DavezDesignz 7 years ago | last reply 5 years ago

Can I Use an LED chaser circuit to make a large, sequenced coilgun? Answered

I saw an easy adjustable speed ten LED chaser circuit on the web and was wondering if I could use it to control relays in a coilgun that would be sequenced and therefore acheive higher velocities than others? Also, could I use a Wimshurst machine and homemade capacitors or leyden jars to power it, or do I have to use a ton of camera capacitors? Thanks!

Asked by mad magoo 9 years ago | last reply 8 years ago

How do you charge a capcitor? How would you connect one to a small high speed electric motor?

I need to know this for a project and I am trying to charge them but it is not really working. I have two small capcitors.

Asked by Sk8terthing 9 years ago | last reply 9 years ago

Distortion pedal project

I was planning on making a motion detector with my roommates but that proved a difficult first project so now we have the plans for a distortion pedal for guitar.Here is the design for it and here is where we are going to buy the equipment (except for the audio jacks which we bought at Radio Shack already).Here are a couple of things we need to know first:1) The plan calls for two 10uf electrolytic capacitors, and the store has those but of 5 varieties with different voltages, which ones should we get?2) What kind of capacitors do we need? Ceramic disk?3) The plans call for a 0.0056uF capacitor yet I couldn't find one like that, can I just substitute one similar? If so, which one?4) If anyone wouldn't mind, could someone explain how this circuit works? Preferably answer the other questions, but I would like to learn how it works also.Thanks a lot to all who answer!

Posted by gohuskies 10 years ago | last reply 10 years ago

Help with capacitor basics? (the math part) [ANSWERED. Come here for the proof if you want it!] Answered

I understand the operation for capacitors, which make a lot of intuitive sense to me, and seems deceptively simple. I know that the derivative  of the voltage across a capacitor (the slew rate, if you will) is proportional to the current, for a given capacitance. So when the voltage is not changing much, like when it is connected across power supply rails, and the capacitor has little-to-no current flowing through it, and it appears as a high impedance. Fair enough. And when I am winding up the wick on the constant-voltage power supply, so that the slew rate is constant, and the voltage is changing at a constant rate, the current will be relative to how fast that voltage rising/falling. Again, that makes sense. I have proven that to myself time and time again. The technical math way of showing all that is this:          dV/dT * C = I or with units plugged in: d(volts)/d(seconds) * Farads = Amps (or something like that)   Likewise, I know that I can do things in reverse, and that forcing a controlled current through the capacitor, that the slew rate of the voltage across the capacitor will be proportional to that. In other words; the voltage will be integrated over time (as it steadily rises or falls). I do not like integrals in math (esp. when they require by parts or partial fractions!), but the concepts do come in handy in practical design! This is also my 2nd favorite way of imagining what an integral are! (My favorite is actually the water cup or well analogy, where a water faucet or hose is a function, and a the level of water in the cup, pool, well, etc. is the integrated result. That makes the function of integrals really clear and deceptively easy LOL!) So, I basicly have been trying to figure out how to take these simple, easy-to-understand relationships, and take ohms law, and have a super basic RC circuit, with 5V, 5 ohms, and 0.1F. I have so far figured out how to take ohms law, substitute I in the capacitor formula, and get a function. HOWEVER, this is where I get stuck. -------------------------------------------------------------------------------------------------------- Here is the circuit:            +5V---(V2)-----/\/\/\/\/\/----(V1)-----| |-------0v----(grd) So after having a bit of a think, I have figured out that I really need to account for 2 different V's. The 5V power supply, V2, and the voltage across the capacitor, V2. I know that the current flowing through everything in a series circuit is the same, so then I can easily figure out current by calculating the voltage drop across the resistor which is this:            I = (V2 - V1) / R  So now, lets plug that into the mysterious capacitor derivative thingy: (All I did was substitute the I in the capacitor formula with the that ohms law formula above.)           dV(1)/dT * C = (V(2) - V(1) ) / R. -------------------------------------------------- Now, I just plug in the values, and simplify as much as I can, to make it more friendly to my eyes. C = 0.1F, and R = 5 in my case, since I am using a 5 ohm resistor, 100mF capacitor, and I know V2 = 5V, since that is the output of a 7805 voltage reg.           d(V(1))/dT * 0.1F = (5V - V(1) ) / 5ohms. That dV/dT is a bit hard to look at, so I will use V prime, or V' to represent that instead:          V(1)' * 0.1 = (5 - V(1)) / 5 I do not know how to simplify that further though, to end up with that weird inverse exponential curve that is the time constant thingy, with that decaying charging curve. I have V on one side, and V' on the other side. :( So this is how far I got:        5 + (1/2 * V(1)') = V(1) EDIT: I HAVE ADDED THE PROOF HERE IF YOU WANT IT

Asked by -max- 3 years ago | last reply 3 years ago

May I know how I can increase the amount of sparks in a leyden jar and how much salt be dissolved pr litre water ?

It is asked inorder to create a perfect leyden jar..

Asked by BANANI 8 years ago | last reply 8 years ago