But, it's not adjustable, unless you use an adjustable reference instead
of the zener. I assume you have in mind a PNP with the collector to
ground, the zener between the base and ground, a base pull-up resistor
base to emitter, and the emitter being the top of our shunt regulator. I
also wonder how "tight" the regulator would be. Seems like the inpedance
would be the r'e of the transistor (25mV/IE) plus the zener dynamic
resistance/beta.
        Thanks for the comments!

Harold


On Wed, 24 Jan 2001 23:37:05 +1100 Roman Black <fastvid@EZY.NET.AU>
writes:
> Harold M Hallikainen wrote:
> >
> >         I have a project that involves a variable shunt regulator
> (10-15V,
> > 200mA). It SEEMS that it should be possible to use an LM 317 or
> 337 wired
> > in some manner to make this work, but I'm not seeing it. Anyone
> see how
> > this might be done?
>
>
> You can use one transistor and a zener, this works
> very well as a shunt regulator as the zener is
> driven from the regulated output and gives a
> good precise regulation.
> -Roman
>
> --
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>

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