The PHILCO Phorum

If you put two .04ufd caps in series you'll get a .02ufd cap. But what happens to their 630 volt rating?

Pepper

It becomes 1260V rating. In theory and more or less in practice.

uh, I didn't think the voltage rating changed.

Yes it did.

Hey Peper,
Long time no post!
Good to hear from you.

Terry

Morzh,
You're right.  Oops, I was thinking parallel, not series.

(12-08-2015, 09:39 PM)Art Hoch Wrote: [ -> ]Morzh,
You're right.  Oops, I was thinking parallel, not series.

 Parallel you double up on the capacity, but the voltage stays the same. I can't remember the physics about why you can connect caps in series to double the voltage rating, but I'm glad that you can, and it works, and have taken advantage of this principle many times. I'm sure that Mike can explain the why, but then again I could just look it up.
Regards
Arran

Arran

The physics is simple: two caps of equal capacitance in series will get charge to exact half the charge each hence the voltage being Q/C, it will therefore be 1/2 voltage across each.
Obviously for exact voltage rating doubling you need exact same two caps.

The half charge is explained by the fact that the same current goes through both caps and so both charge equally.