🚀 go-pugleaf

In <1112@tsdiag.ccur.com> davet@tsdiag.ccur.com (Dave Tiller N2KAU) writes:

>How about:
>                  /       /  
>------800V------>|------>|--------/\/\/-----600v----<load>----
>                /       /           R                         |
>              100V zener 100V    (I limit)                  <GND>

Ouch!  First of all, the Zeners should be facing the other way -
we're interested in reverse breakdown voltage here.  The above circuit
will give you a very nice 798V or so supply

Secondly, with the zeners in series with the load, one-quarter of the
total power dissipation takes place in the diodes which is rather
nasty.  (Same current as load through diodes; 200V across diodes.)

Thirdly, having a current-limiting resistor as shown before the load
makes the output voltage rather heavily dependent on the load current.
Suppose you have a 5-ohm I limiting resistor.  Draw 5A and your output
voltage drops by 25V!

Some other circuits posted here, such as the emitter-follower types,
are more appropriate.

>-- 
>David E. Tiller         davet@tsdiag.ccur.com  | Concurrent Computer Corp.
--
David F. Skoll        | Department of Electronics | Opinions expressed here are
dfs@doe.carleton.ca   | Carleton University       | my own and not necessarily
(613) 786-7515        | Ottawa, Ontario, Canada   | those of my employer.