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

Question by Balls of Kevlar   |  last reply


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.

Topic by tigerdog330   |  last reply

Capacitor? Answered

Can I make a capacitor out of plaster Paris/fix-it-all and washers ?

Question by wiccakingkamui   |  last reply


Hey, selling a massive box of Cap's.... see here if interested;;=151394654697#viTabs_0 Thanks!

Topic by 75lockwood 


Hello my friends, i didnt post any instructable latly because i am in school and end is near.... but now i am working on few projects, and for one of them i need capacitor 1f 5.5 v. so my question is how long can this capacitor power the single white LED?

Question by tealk   |  last reply


So i'm trying to make a power supply, so for example if i make one with just capacitors (ill put a schematic if i can) and i hook it up to a device,Will it just discharge immediately or will the charge ask for a while?

Topic by minecraftpotato   |  last reply

about capacitors

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

Topic by kendallickes   |  last reply

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!

Topic by DELETED_DELETED_basementhacker   |  last reply

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.)

Question by V-Man737   |  last reply

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 :)

Question by The Prickly Potato   |  last reply

substituting capacitors

I was designing a board that uses a bunch of the same chip and all of the inputs require a capacitor. For example lets say I have 10 identical chips with identical setups. Instead of having individual capacitors for everything to ground (except for the outputs) can I combine all of the ceramic capacitors and use a couple of bigger electrolyctic capacitors? So lets say I can have 1 capacitor for all of the identical inputs instead of 10 smaller ceramic ones. But for stuff like timing do I need individual capacitors?

Topic by guyfrom7up   |  last reply

Replacing capacitors...?

I need to replace three 470 uF 25V caps but I was wondering if using 1000 uF 25V caps would work or not?

Question by gr33ko   |  last reply

Are these Capacitors Fried??

I think i blew out a cheap voice chance I have... can anyone verify that the capacitors I have circled are indeed blown... I've never looked before, and am not 100% sure the black isn't just a manufacturers marking. also, the caps are 20pF and 56pF and I need to replace them STAT... would Radio Shack's 100 pack capacitor grab bag have these numbers?

Topic by gschoppe   |  last reply

capacitor control

I was just wondering if anyone knows any methods of controlling the energy discharge from a capacitor..

Topic by nuncoop   |  last reply

Capacitor problem Answered

I needed a 2.2 and a 10 uf capacitor to make a metal detector, but the values printed on my capacitors are not less than 5. I want to find that if the values on the capacitors are in uf, nf or pf. And if they are none of them. 

Question by tanyutsharma   |  last reply

Capacitor Value

Can someone identify the following MDC.05 +80%Z5U 20%1KVIs this a .05uF capacitor rated at 1000volts?

Question by TedD   |  last reply

Microwave capacitors? Answered

Is it possible to put 25 microwave capacitors (2kv 1uF) in series and running 40kv through it without them failing?

Question by The MadScientist   |  last reply

What are capacitors for? Answered

What are they for I've seen them everywhere... are they used to hold power?  

Question by RelientOwl   |  last reply

Resistors and capacitors Answered

Can any one tell me how can we use and install resistors and capacitors? And how can we study the resistors and capacitors

Question by k.bipin   |  last reply

capacitor resistance

Why is it that as super capacitors capacitance goes up the internal resistance goes down? I'm looking for a tiny capacitor that can supply 0.3 volts20mA (I'm going to be powering flexinol, not an LED) for 1 second. I don't want the capacitor to be huge because I'm making a beam bot where size is a factor for charging time and because of it's physical size.

Topic by guyfrom7up   |  last reply

Capacitor Charging?

How do I charge a capacitor rated for 450v at 1150uf using 2 AAA batteries? I tried using a mini transformer but it takes a very long time. Is there a quicker solution? Thanks in advance, IndianHacker

Question by IndianHacker002   |  last reply

for what this capacitor is ? Answered

I can't find 4.7pF ceramic capacitor

Question by Rendydevara   |  last reply

Is this a capacitor or a battery? Answered

In regards to my "battery free bike light".   I was told that a dynamo flashlight charges a capacitor.  Is this the case? Take a look, Thanks

Question by onrust   |  last reply

Help with capacitors

Hello everyone. I've seen this instrucable ( that uses a charged capacitor to light up a LED.I found this very interesting, so I started investigating what a capacitor is.So far so good and my questions are:- Can capacitors be used as replacements for batteries? I'm thinking specifically to light 1, 2 or 3 LEDs.- If so, how can I calculate the specs of a capacitors for a determined amount of LEDs.- Is it possible to calculate how much time the capacitors will keep the LEDs lit?- How can I determine if the capacitors have enough charge to light the LEDs?- Would you be kind enough to suggest a circuit to achieve any of these?Thank you.

Topic by transistor   |  last reply

Capacitor question?

I would like to know if I can hook up a capacitor to the incoming power being generated by my windmill so I can up my outage? I've been reading that you can use a capacitor bank to step it up. Thanks?

Question by swat420   |  last reply

are these really capacitors?

Http://'m only asking because either the manufacture doesn't know what they're talking about or it's a battery with it's capactance measured in farads. The say rechargable capacitor. That's the only reason why I feel causious

Topic by guyfrom7up   |  last reply

capacitor help

Hey everyone i was wondering if someone could help me, I have a capacitor row (as shown below) and i was wondering what i could do to make it a shocker type thing? Any help would be greatly appreciated.

Topic by lakeside69   |  last reply

Capacitor charger

I want to build a fast simple capacitor charger with minimal components. i was going to builda dc to dc converter. but then came across this picture from here i am going to replace the switch with a 555 timer and transistor . does any body know if this circuit is any good or has any body built it

Topic by chrischavez   |  last reply

Capacitor Help

I am trying to build a lab power supply which I need to complete in order to continue an electronics course I am taking. The schematics require two 4400 uF capacitors, which for the life of me I cannot seem to find on any website or store. I was wondering if it is possible for me to use a slightly higher capacitor without causing electrical problems?

Topic by Sedgewick17   |  last reply

Charging a capacitor? Answered

Recently I've had an idea for a project that requires a relatively low voltage (5 to 30 volts) capacitor bank. However, that capacitor bank needs to be charged. While I do know you can easily just hook it up to power, I find that too simple, and lacking of safety, and knowing when it is fully charged. So, could anyone please enlighten me on how i can charge my cap. bank relatively slowly, with, say, an LED that lights up when charged (to avoid them blowing up in my face), and a kill switch/button that discharges the capacitor bank in the event of an overcharge. If anyone could provide an explanation or circuit diagram that would be great, thanks. BTW, the capacitors I was planning on using are or

Question by LiquidLightning   |  last reply

Capacitor Power

I want these so badly, and I live relatively close (about 300 miles away).|66%3A2|65%3A15|240%3A1318&_trksid=p3286.c0.m14You can make one heck of a capacitor bank, releasing almost half a megawatt in a split second.My only problems:I don't have 1600 dollars, crycry.These things are so large that if I were to line them up side by side (so that the thinnest parts create the overall thickness) it would be 25 feet long, 14 inches wide, and almost a yard tall. THE POWER BOGGLES THE MINDI'm so mad, if I was an adult I'd buy these in a heart beat... sigh... deal of a life time... I hope not...and best of all, they are PULSE CAPACITORSthoughts? comments?

Topic by guyfrom7up   |  last reply

Capacitor charger? Answered

Ok so im planning on building a portable coil/rail gun. But one issue is I cant quite find a circuit that would work best to drive a custom transformer. The charger I have now is a flyback driver that I used a wall adapter to power. I just need some advice and maybe schematics. Thanks, bud

Question by budhaztm   |  last reply

16Volt Capacitors

Hi everyone, I took apart an old Amateur Radio i had lying around and the boards have loads of parts, im wondering what i can use some of them for, most of the boards inside have lost of 16v capacitors and ive read instructables on making battery free torches etc, would these be of any use fpr these type of projects? Ideas welcome :) Cobs

Topic by Cobra_SFX   |  last reply

Giant Capacitor

Our microwaved died in my house so I took it apart for parts. I found a Giant Capacitor, its about 4in x 2in x 1in It has 3 Leads coming out of it and somthing that attaches to a panel, im guessing the ground. Does anyone have any idea what i could do with this let alone charge and have it release its energy all at once. Of course I have to clean it and am aware it could kill me at any time.

Topic by acer73   |  last reply

what is a capacitor battery/battery capacitor?

What are batt-caps, how do they work, and how would 1 be wired to a 1.5v battery? what are some specific names of different batt-caps?

Question by freenergyfuture   |  last reply

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

Question by RaviT120   |  last reply

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

Question by D3zire   |  last reply

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"?

Question by Fypsigon   |  last reply

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"?

Question by Fypsigon   |  last reply

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.                                               

Question by Atul009   |  last reply

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?

Question by -max-   |  last reply

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.

Question by -max-   |  last reply

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?

Question by deepakmurali   |  last reply

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)

Question by -max-   |  last reply

Need Capcitors

I Need Capacitors Bad!!! Any Size.

Topic by wolf996   |  last reply

Polarity of tantalum capacitors

Howdy all, Recently got back into basic electronics and have started building kits. Been building a kit that uses tantalum capacitors and it notes that polarity orientation is very important. The question I have is: is there some un-published indicator of how polarity is indicated on these tantalum caps? I've been over these things with a microscope, even bought new ones, but other than the values & manufacturer, I can find no obvious sign of polarity. Leads are the same length and not marked. What am I missing? Thanks in advance for any help. Dave

Topic by gutbucket   |  last reply

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

Question by DieslV   |  last reply

Help with charging capacitors

How do I charge my 450v capacitors with a 120v outlet? I am building a rail gun and need to get these up to a high enough voltage. 

Topic by gclark0812   |  last reply