Re: capacitor

--- In CAD_CAM_EDM_DRO@y..., "Mike Snodgrass" <snarf@s...> wrote:

> Hello, I have a variac rated at 60A, and plan to rectify and
> filter the current at my driver enclosure, to power my geckos.

What value of cap would I need? I realize it would

> have to be rated at higher than required voltage. Also could I use

a AC cap ahead of the rectifier?

> Thanks
>
>
> [Non-text portions of this message have been removed]

Mike, I would be very careful about that set-up. First, the VARIAC
is not an isolation transformer. There's a real chance of getting
fried! Second, the general rule I use is 1,000 mfd per AMP, so you
would need a 60,000 mfd capacitor rated at 250 volts. That may not
be easy to find. An AC cap isn't going to help filter the line.
The bridge rectifier blocks current from going back into the line so
that's where the cap comes in to "filter" during the low peaks of
voltage once it's been converted to DC. The cap stores voltage while
the line is up and then releases it when the line goes down. But the
capacitor has to be big enough to provide current for the load.
The voltage rating has to withstand the highest applied voltage plus
a safety margin. I repeat, BE CAREFUL.... It scares me...
Gary