[AMPS] Screen regulator circuit needed

[Steve Thompson]

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.

Steve

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