AC power on front panels

Chuck Guzis cclist at sydex.com
Sat Jan 14 15:44:38 CST 2006


On 1/15/2006 at 8:59 AM Dave Brown 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
h%20.pdf

Very nice job, particularly using the grounded/earthed neutral as the
return.  Here in the USA, one side of the 120vac is tied to the third prong
of the mains receptacle in the distribution panel, so this would also be a
way to avoid tying into an incorrectly-wired receptacle (more common than
you'd think!). 

Back in the bad old days of glass-enclosed active devices, a dodge for
powering a single 6.3v 0.3a filament from the mains without a filament
transformer was to use a 1.0 uf nonpolar cap as a dropping device.  In that
application, if the cap failed, the filament of the tube/valve would simply
burn out.  Perhaps a very small (7w) incandescent bulb might be used in
your circuit in place of a 100 ma fluse.  Would a common NE-2 neon also
work as protection?  It might be nice to use as a "this equipment is
connected to the mains" indicator.

Cheers,
Chuck







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