Unknown capacitor

[GoGeTa006]

k. . .I came across this "flash charger" that was used by a photographer. . .obviously to charge the flash lights (the BIG ONES) you know those that have stands and all.
ok so I dissasembled it and found this huge capacitors (around 10 cm tall, diameter of around 4 cm). . .im eyeballing it.

ok so I look at this capacitors and they have nothing printed on them. . .some numbers and stuff that I looked online and couldnt find anything. . .I used some oscilometer and stuff to measure resistance  .. .and I came around 1000 micro farads.
Now im trying to find the voltage. . .

I was thinking of frying it. . .but I dont want to waste it. . .
anyone knows how to know the voltage capacity of a capacitor?

the purpose of this. . .is (if you read my last semester post about a railgun and coil gun. . . well you can go from there)

[bloody000]

AFAIK the voltage is just a rating and as such cannot be simply measured.

[darren42]

the capacitor should have something written on it, otherwise it will be next to impossible to detail the voltage rating

[BuriaL]

I dunno much about this but google spit out some info.
Maybe its helpful. If you know the charge and capacitance you can calculate voltage?
*shrug*

http://www.kpsec.freeuk.com/capacit.htm

[GoGeTa006]

I dunno much about this but google spit out some info.
Maybe its helpful. If you know the charge and capacitance you can calculate voltage?
*shrug*

http://www.kpsec.freeuk.com/capacit.htm

charge is something else.
i know the capacitance and thats it.

the capacitor should have something written on it, otherwise it will be next to impossible to detail the voltage rating

nop! it has numbers and everything but I googled it all up and came across nothing. . .I tried looking it as a part number from this thing and nothing either. . .
Tho by seeing this flash charger's name
norma 800 . . . . I think theres a chance of that being the voltage. . .altough that is EXTREMELY high. . .i was guessing around 500 at the most. . .but i wanted an exact measure. .
but well. . .if it cant be done then it cant be done,. ..

[kostya]

What do you mean by voltage of a capacitor? The voltage difference between the terminals? Isn't that just going to be whatever voltage power source it was charged off of?

[GoGeTa006]

What do you mean by voltage of a capacitor? The voltage difference between the terminals? Isn't that just going to be whatever voltage power source it was charged off of?

yes but no. . .
if you hook it up to a 9v battery it will have 9 volts. . .
but if you hook it up to a voltage multiplier . . .thats a different story, the capacitors have a voltage limit.

say grab a disposable camera, break it appart you have a 200 uf 300V capacitor. . .you charge 300 volts out of a 1.5v battery. . .

[boxer4]

Just sticking in my 2 cents here, even though it's already been covered.

No, without destructively testing a capacitor, you can't tell the WVDC (working voltage DC) or max surge voltage of a capacitor.  You must refer to numbers printed on it.

However usually you can make a good guess.  Provided that your measurements are correct (4cm diameter, 10cm long, 1000uF), that the capactor is in good shape, and a 1990s capacitor, I'd say this is somewhere around 50 to 100 WVDC -- but this is from experience.  However, this could be totally wrong as there's no way for me to tell how the capacitor was made.  Also "good shape" as it's not dried up or anything, this will reduce capacitance leading to an incorrect guess to its WVDC.

And bah, 4cm dia 10cm long... that's tiny...

(and I think my 0.3F ~10cm dia 15cm tall capacitor is actually small compared to the industrial gallon paintcan sized and even larger for motor starting and power factor correction capacitors.)

[GoGeTa006]

Just sticking in my 2 cents here, even though it's already been covered.

No, without destructively testing a capacitor, you can't tell the WVDC (working voltage DC) or max surge voltage of a capacitor.  You must refer to numbers printed on it.

However usually you can make a good guess.  Provided that your measurements are correct (4cm diameter, 10cm long, 1000uF), that the capactor is in good shape, and a 1990s capacitor, I'd say this is somewhere around 50 to 100 WVDC -- but this is from experience.  However, this could be totally wrong as there's no way for me to tell how the capacitor was made.  Also "good shape" as it's not dried up or anything, this will reduce capacitance leading to an incorrect guess to its WVDC.

And bah, 4cm dia 10cm long... that's tiny...

(and I think my 0.3F ~10cm dia 15cm tall capacitor is actually small compared to the industrial gallon paintcan sized and even larger for motor starting and power factor correction capacitors.)

thats small. . .
I really tought it should be well over 300v since its used for a flash.. . .or maybe i got you wrong and WVDC is something idfferent?
well i got my small capacitors that i took out of a flash disposable camera, 300v around 100-200uf

[sdedalus83]

I'm so used to dealing with solid state audio electronics that a 4cm x 10cm 1000uF capacitor soundsfreaking huge.

Checking panasonic's electrolytics catalog came up with a 4cm x 8cm 450V 1000uF cap.  Considering the one you have is probably a lot lower quality than the panasonic, I wouldn't be surprised if it's rated for 750V or more for it to be that big.  A camera flash is going to have extremely high voltage requirements with almost no current draw, so that sounds about right.

[GoGeTa006]

I'm so used to dealing with solid state audio electronics that a 4cm x 10cm 1000uF capacitor soundsfreaking huge.

Checking panasonic's electrolytics catalog came up with a 4cm x 8cm 450V 1000uF cap.  Considering the one you have is probably a lot lower quality than the panasonic, I wouldn't be surprised if it's rated for 750V or more for it to be that big.  A camera flash is going to have extremely high voltage requirements with almost no current draw, so that sounds about right.

yup./ . .im used to small capacitors too. . .so when i held that in my hand (instead of my fingers) i was like OMFG. . .im gonna kill someone

[sdedalus83]

Although I've used black gates before and a 50v 1000uF cap would be about that size.  The cost was also obscene.

[boxer4]

I suppose I'm trying to be conservative here, going over your WVDC of the capacitor is dangerous (possible explosion).  Yes it could be well into the hundreds, it's hard to tell.  I highly doubt the WVDC of the capacitor is in the 1000V range and I'd put an upper bound of around 500V as it may be newer than I thought; again it's a guess.  At 1000uF that's a fair large capacitance there, usually people don't make high voltage capacitors at that capacitance.

And yes this picture was to be somewhat hilarious:

caps (it's a link to cut down on bandwidth for people who really don't want to look at round cylinders)

Most of these capacitors are really old, except for the three "tiny" ones in the front (there are many SMT caps are smaller).
(My project with these capacitors was a little less destructive than a railgun/coilgun.  I was planning to make a small welder with them.)

[Talapus]

This is the biggest cap I have played around with:

(click to show/hide)

Yes, that is a 19 inch rack

80μF, 10kV