Thanks everyone for the suggestions. In the meantime I realised it is so
sensitive with the load (R3 on that simulation I attached in the original
post). With the R2, yes, I know in the original circuit it should be
connected to the collector, however, I used a modified version of it (the
idea is coming from this proceeding:
http://www.essex.ac.uk/dces/research/audio_lab/malcolmspubdocs/J8%20Optimization%20of%20the%20amplified%20diode.pdf)

Anyway, a zener with an emitter follower would be sufficient enough but then
the cost comparable to those regulators you guys mentioned, so I'll give
them a go. BTW this project is quite cost sensitive and also have a limited
size.

Thanks again,
Tamas


On 11/1/07, Russell McMahon <apptech@paradise.net.nz> wrote:
>
> > A linear pass regulator is very likely a better solution.
> > They are cheap and their performance will be in a
> > different league.
>
> Probably. But there are several shunt regulator diodes
> around that are ultra cheap because they are used in
> zillions. The LM385 is cheapish and the lower spec TL431 is
> about the cheapest IC you can buy, ($US0.40/1 down to under
> $US0.08/large_volume).
>
> FWIW the lovely CD40106 is just dearer at high volume and at
> under $US0.015 a Schmitt inverter may be the best value IC
> ever known.  Not so good as a voltage regulator though :-)
>
>
>
>         Russell
>
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