AW: Power supply musings

[Haible Juergen]

I got good results with two big diodes in parallel (opposite direction).
No hum voltage below 0.5V will find a closed loop, but higer voltages
will find the diodes conducting in both directions. A 47nF ceramic cap
across the diodes ensures that the enclosure still works as RF shield.
(Forgot to mention: The enclosure is still on earth ground. The components
are between enclosure and signal GND.)

JH.

	>----------
	>Von: 	Rene Schmitz[SMTP:uzs159 at uni-bonn.de]
	>Gesendet: 	Freitag, 11. Juni 1999 11:13
	>An: 	synth-diy at mailhost.bpa.nl
	>Betreff: 	Re: Power supply musings
	>
	>At 06:25 11.06.99 -0400, you wrote:
	>
	>>If you break the audio shields, you are asking for noise
problems...so I
	>>break the mains ground... and isolate the chassis from each other
(humfrees
	>>are a commercial variety of the technique I use, nylon shoulder
washers)
	>>
	>>Noise is gone. Some say that I am at risk this way (safety)... I
think the
	>>audio cables are more than adequate to handle the fault currents
long enough
	>>for the breaker to trip. Most Audio gear can have the "3rd pin
ground"
	>>safely plugged into one central common point. I pulg into the wall
at
	>>exactly one point, and run a dozen outlets right from that point.
	>
	>I do it the same way. To add safety when the gear is NOT connected
to other
	>devices (at least one of which must have a connection between
circuit and
	>power gnd) you can place a small neon bulb between circuit and
mains gnd.
	>The bulb is a perfect insulator at small voltages, however a
voltage of
	>about 65V will make it conduct, and relatively low ohmic (sp?). 
	>Of course you should use a transformer with seperate chambers for
primary
	>and secondary winding, where you are allowed not to ground the
secondary
	>winding. 
	>
	>Bye
	> René 
	>
	>             ,   : (uzs159 at uni-bonn.de)
	>|") [" |\ | ["   : (http://www.uni-bonn.de/~uzs159)
	>|"\ [_ | \| [_   : (http://members.xoom.com/Rene_Schmitz)
>                        
>