[AMPS] Screen regulator circuit needed

[Rich Measures]

>
>In message <19981115133322.AAB2436@[209.239.238.94]>, Rich Measures
><measures@vc.net> writes
>
>snip
>
>>€  Bipolar transistors have a secondary-breakdown problem which makes 
>>them problematic in HV pass regulator service.  Power FETs are virtually 
>>immune to secondary-breakdown.  .  From my experiences, National 
>>Semiconductor's 723-based "positive floating regulator" circuit (using 
>>FET pass transistors) is good for regulating screen potentials.    2000v 
>>regulated output is practical with 600v-rated FET pass transistors.    
>>Since FETs operate with zero gate current, paralleling FETs for more 
>>current is easy.
>
>Only if they have the same, or fairly similar gate threshold voltages -
>not a problem with same types having same date codes but beware of
>mixing date codes or type numbers without measuring first.

This is why I use an equalizing resistor in the series-pass reg. circuit 
on my Web site.  FETs should not be paralleled without equalizing 
resistors.  
>
-  later, Steve


Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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