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[Amps] Bleeders

Subject: [Amps] Bleeders
From: "John Lyles" <>
Date: Wed, 29 Feb 2012 18:19:48 -0700
List-post: <">>
For the big power supply for my TH628 amplifier, 28 kV with 225 uF, do not use 
a high power bleeder. It is a pulsed amplifier, so we need all the current we 
can get, during each mS long pulse. There is a slow trickle bleeder (meter 
multiplier) along with capacitor leakage current, which can take a long time to 
The normal bleed down is a string of very long Carborundum 2 K resistors in 
series, dropped by a big Ross HV relay across the terminals, followed a couple 
seconds later by another Ross HV relay that is a hard short to ground. Then, to 
open the door, there are additional switches as well as big long chicken sticks 
that are used to touch the output. Along with this goes a mountain of paperwork 
and training to satisfy even OSHA. The relay timing is all done automatically, 
so as not to drop before the HV charging supply is off. Reverse is true on turn 


> Message: 1
> Date: Wed, 29 Feb 2012 16:03:45 +0200
> From: "Alf Pousar" <>
> Subject: [Amps] Bleeders
> To: <>
> Message-ID: <F6EDB8E3CF3845EFB10119AC490846E9@fast>
> Content-Type: text/plain;     charset="iso-8859-1"
> Why not skip the bleeder entirely, and make a current discharge circuitry 
> when the session is over. 
> If the anode voltage is very high then stack some thyristors and fire them 
> with opto couplers.
> So when you hit the big switch it turns off all power to the power supply, 
> except for the auxillary
> circuit that keeps the draining alive and then shut off .
> Not very compicated to do and you get rid of the bleeder heat.
> Alf OH2QM

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