Charging up a cap

I have a 10,000mfd/16v electrolytic cap that I need to charge up. I am using a 120vac/12vdc 240ma transformer to do this. About how long should it take to complete the charge?

Thanks, Lar

Reply to
Larry B
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Hooking it up to the power supply and measuring the voltage would have been way quicker than typing up your message. That said, t=R*C , where R is the impeadance of your charging circuit. A rule of thumb says it should be full in approx. 5*t.

Michael

Reply to
Michael Hofmann

I am

have

circuit. A

Sorry my response took so long. Wife had surgery. AOK now.

I know enough to be dangerous and do not need an exact length of time on the charging issue. I don't have most of the requested variables (impedence of the transformer, wire inductance, forward drop of the diode).

If it is true that overcharging (assuming a 14vdc charge into a 16vdc cap) will only reach a "stasis" point and not damage the cap, what would be a safe amount of charging time needed to get close to a full charge (making typical assumptions for the unknowns).

Thanks, Lar

Reply to
Larry B

First approximation of t in your case is 1 second. So in about 5 secs it should be fully charged.

Michael

Reply to
Michael Hofmann

full

secs it

I must have a bad cap. Once charged, if I short it to discharge it, I get no spark or snap.

Larry

Reply to
Larry B

You can test the cap using an analog volt meter, test for impedance, then reverse the leads, the needle should bounce and then the cap would discharge. Usually works for me, that and a brief visual inspection as most caps that I've seen have visibly failed (overheated, cover has shrunk, etc.)

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Myron Samila
Toronto, ON Canada
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Reply to
Myron Samila

the cap (which is brand new) reads open in one direction (+ to +).

then reverse the

Usually works for me,

visibly failed

up.

long

a

it, I

Reply to
Larry B

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