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tube-type bridge rectifiers




From:  Bill the arcstarter [SMTP:arcstarter-at-hotmail-dot-com]
Sent:  Saturday, February 07, 1998 10:58 AM
To:  tesla-at-pupman-dot-com
Subject:  Re: tube-type bridge rectifiers

It was written:

>----------
>From:  Bill the arcstarter [SMTP:arcstarter-at-hotmail-dot-com]
> Can anyone suggest a rectifier tube capable of perhaps 100-200 ma of 
>plate current at about 15KV or so?  I'd eventually like to move this 
>onto my pig...
Am I missing something here ? - why not use strings of 20 or so
1N4007's - 20KV at 1 amp for a couple of bucks - too fragile maybe ?
how about 1N5408's?
     ____                                                           ____
   _/ L_/  Mike Harrison / White Wing Logic / wwl-at-netcomuk.co.uk  _/ L_/

Well - I've had bad luck doing this using discrete diodes.  Once I made 
a bridge using two 1N6000 diodes per leg - and ran it on 7500 volts.  I 
used a safety gap with a small 500pf doorknob cap across it, series 
resistance and series inductance after the bridge.  It lasted 30 
seconds... (I'm told the 1N6000 are good for 6KV but haven't verified 
this)

But - I did pull a bridge out of a commercial X-ray transformer tank - 
each leg of the bridge consists of about 15 discrete diodes in series, 
w/o ballasting.  Two of these bridges were used to provide 140KVDC at 
200mA to an x-ray tube.  I'd hate to kill it so I've not tried using it 
for coiling yet.

I'm told that tube-based bridges will take a substantial amt of abuse 
w/o failure.  That sounds good to me.  I have a whole heap of filament 
transformers (at 140KV isolation, out of other X-ray equipment), so 
powering the tube heaters won't be a problem...

All comments welcome.

-Bill the arcstarter
http://www.geocities-dot-com/CapeCanaveral/Hangar/6160


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