[sdiy] [ot/3] Using ElectrolytCapacitors

[harry]

Hi Timo

Y'gonna get yerself killed (likely)

Electrolytic capacitors in an AC line could (probably) be very dangerous...

Even with the configuration you have shown (bipolar)... you will need
resistors across the caps, you probably need to match the values, you
would probably want to use inverse series diodes to limit reverse voltage
on the cap that is reverse biased... and

Electrolytic Caps have (relatively) poor RIPPLE CURRENT ratings... this
is the ability to handle an AC current waveform, as opposed to the DC they
are used to dealing with. Unless something will inherently limit the
current to
a value well below the ripple current rating, they will get hot and either
live a short
life before they blow... or just blow !!!

Search for a FILM CAPACITOR (many companies make these, such as
Cornell-Dubilier) replacement for an electrolytic cap. They are non
polarized,
have probably 10x the ripple current rating of the equivalent
electrolytic... and
you need only 1/2 the capacitance

(Remember when you put the electrolytics in series... you needed twice the
capacitance in each can)

The price may be higher... size of one film is probably about the same as
two
e-lytics... they will weigh more.

Still.. be sure to watch out for the ripple current rating.

And good luck.

BTW I have never been happy with the back to back electrolytics... I have
blown them up every time.  If you want to talk offlist e-mail me direct and
we
could discuss what you are trying to do...

H^) hary

Timo Weggen wrote:

> Hello,
>
> first, I'm no engeneer, I don't know very much about electronics, but I
> am eager to learn. Thus I listen what you all write here.
> Now, in an experimental circuit, I need quite beeg (470uF) capacitors
> in a AC line.
> My father told me recently, he'd used successfully used ElectrolytCaps
> like that, and it worked:
>
> ---[]!--![]----
>
> (Instead of a single hige --||--)
>
> But I am not sure I got it right, and I also want to understand it.
>
> TIA
>
> Timo