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
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|