"Adrian C" wrote in message
...
N_Cook wrote:

Looks like a regular linear ps to me except for the transformer being
about
4 times the size necessary for a preamp and relays - more superfluous
weight.
Pair of 3300uF caps , 78M18,79M18, 5V reg , no chokes, no mu-metal or
anything noticeably odd but, at least, no gold plating.

Doesn't sound anything special. 78M18 and 79M18 are bog-standard regulator
chips.

I was wrong in calling it a "very clean power supply". I should have said
"it has the effect of a very clean power supply"....

Have a look around the preamp section. As from the link I gave (from
google), it's not a regulator but an "active filter".

Quote "tracks input voltage as changed by variations in line voltage and
load, and takes out some AC. That may be useful under some special
circumstances. In the tube days, this was done using a large choke, that's
in a way what this circuit simulates."

Active filters in power supplies are common when low ripple is required but
voltage stabilisation is not required. At it's simplest it's just an emitter
follower with the base fed from the input via a resistor and decoupled to
ground by a large capacitor. If the current loading is high a compound
transistor (darlington pair) might be used. Again nothing special there,
they've been used for years (thermionic version were in use before the
invention of the transistor).

FWIW I tried a patent search. Got nothing.

Not original enough to be patentable.

David.