The cap is to reduce ripple to a level that wont cause chatter in the relay.
A higher value cap reduces the ripple further and there is finally some
finite value where the ripple is at zero.
Theory is in the PS section of any ARRL or other handbooks going back into
the 20's.
I usually use 150-220 MF in such a circuit as I use 24VDC relays to do all
my remote antenna switching and phasing. Again, it is not critical. If the
relay doesnt chatter youre good to go.
Carl
KM1H
Carl
KM1H
----- Original Message -----
From: "JT Croteau" <[EMAIL PROTECTED]>
To: "Discussion of AM Radio in the Amateur Service"
<[email protected]>
Sent: Thursday, February 14, 2008 9:13 PM
Subject: Re: [AMRadio] Cap Substitution
On Thu, Feb 14, 2008 at 7:13 PM, Jim Wilhite <[EMAIL PROTECTED]> wrote:
I read you are rectifying AC to power a DC relay. If that is the case,
I would go to a higher value cap for the filter. Say about 100 uf or
more.
Ok, and what would be the theory behind this.. I'm somewhat ignorant
on some of this stuff. The original schematic of the schematic I am
repairing calls for 50 uF but I don't have that value in my junk box
but I do have 47.
Thanks
--
JT Croteau, N1ESE - Manchester, NH (FN42gx)
Contest Manager, TARA Skirmish
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