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From: liz@poppyrecords.invalid.invalid (Liz Tuddenham)
Newsgroups: sci.electronics.design
Subject: Re: LTSpice model for a SiC MOSFET
Date: Thu, 22 May 2025 16:50:25 +0100
Organization: Poppy Records
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john larkin <jl@glen--canyon.com> wrote:

> On Thu, 22 May 2025 09:44:30 +0100, liz@poppyrecords.invalid.invalid
> (Liz Tuddenham) wrote:
> 
> >john larkin <jl@glen--canyon.com> wrote:
> >
> >[...]
> >> Going from 1KV to 3.3v has interesting possibilities. The easy way is
> >> a resistor and a zener. Efficiency about 0.3%.
> >
> >Roughly 1W dissipation per mA , so if the current requirement isn't too
> >high, that is probably the most straightforward system with very little
> >to go wrong. 
> >
> >
> >> More efficient would be a resistor and a zener and then a buck
> >> switcher. 5% maybe.
> >
> >That's a lot of extra complication for very little improvement, the
> >resistor still has to carry the full load current.
> >
> >For a cult market you could use an 807 and tap the 3.3v off the cathode
> >bias resistor.  (or better still, rectify the heater supply and use a
> >linear regulator but don't tell the customer).
> 
> I never liked 807's. Ugly tubes.

Ah yes.  For that market, appearance is everything.  

A much better-looking bottle would be a PY81 but, although it is
specified to withstand a peak anode voltage of 7 kV, the maunfacturers
only allow that under cutoff conditions.  It also uses a standard B9A
base, which is still easily obtainable.


-- 
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk