In article , Dave Plowman (News)
wrote:


I expect Jim will be along with a more sophisticated PS arrangement
shortly ;-)

Not really. :-) I have tended to design PSUs on a more 'specific' basis.
Thus I have some preferred topologies, but wouldn't comment too much on
component values, etc, without knowing more about the details. Not made a
PSU for the purpose Andy describes, so can't comment in detail beyond saying
that what you/he have discussed looks fine to me.

FWIW I *do* have a prefered topology, aimed at low noise/ripple rather than
being a rigidly predefined voltage. Also ensures a slow start-up and
decline when turned on/off which is important in some applications.

http://www.st-and.demon.co.uk/Audio/700/700page5.html

If you look at the above page it shows an example of the form of PSU
that I tend to use when low noise is desired. For the example shown
the required voltage was around 20Vdc and the output current around
100mA. I tend to avoid feedback or ICs in such supplies as my
experience (perhaps now out-of-date) was that these tended to
either give more noise, or risk unintented HF instabilities under
some conditions of use.

If interested in the above, you would probably wish to fiddle with
some of the component types and values. :-)

Above said, I can't say that the design I've used would be 'better'
than what you have already tried, but offer the above in case
it is of interest.

Slainte,

Jim

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