14 Jan
2006
14 Jan
'06
11:59 a.m.
----- Original Message -----
From: "Chuck Guzis" <cclist at sydex.com>
To: <cctalk at classiccmp.org>
Sent: Sunday, January 15, 2006 7:45 AM
Subject: Re: AC power on front panels
On 1/14/2006 at 11:09 AM gordonjcp at gjcp.net wrote:
For a practical implementation of this sort of arrangement see the
circuit here-
http://homepages.ihug.co.nz/~tractorb/collins/Collins%2075S%20mains%20switc…
I threw this together to get round an issue with under-rated wafer
switch contacts being used for mains switching.
Regards
DaveB, NZ
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Surely a transformer would need to be powered all
the time?
So what? Your central heating system and doorbell have one. Much,
if not
most, modern electronic equipment, such as PCs, televisions, etc.
all have
some tiny draw from the AC mains even when powered off. If all
you
needed was a very small DC supply you could do away with the
transformer
and perhaps use a couple of capacitors in series with each side of
the
line, followed by a rectifier and a zener--it wouldn't provide quite
the
isolation from the line that would be ideal, but it wouldn't need a
transformer.
Cheers,
Chuck