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Re: Hum help (Was Radio Shack Attenuators)

> Speaking of blank stares, I've got a 12V, 20 amp power supply that
> is generating a hum.  I understand that I can put a capacitor
> across the positive and negative terminals.  How big a capacitor
> should I use?

The general rule of thumb I heard about a million years ago was 1000
microfarads per amp of current draw.  However this applies to what you are
putting before a regulator or in an unregulated power supply.  To add
something to the output of an existing (I assume regulated) power supply,
you want quite a bit less than that.  A better bet would be to determine
why a previously working regulator is not doing so.

Jim Walls - K6CCC
Mobile Radio Operations
Southern California Edison Co.
Ofc:   626-302-8515   -   PAX   28-515
FAX:   626-302-7501   -   PAX   27-501

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