terryS wrote:

But I've also read that the variuos 'command' receivers (BC453, 454
etc,) will work well with much lower B+ voltages.
Which are much kinder on the 60 year old decoupling capacitors etc.
can't remember the value but could it have been as low as 120 volts
DC?
Cos it occurs to me that one could use a 150 volt gas regulator tube
(OD3?) on the output of a power supply to achieve that?

You might be able to do a shunt regulator, since the current demands are
small. Be more reliable to use a solid-state series regulator made with
a zener diode string and a TIP50 darlington. You could use an OD3 and a
6L6, though, I think.

But, since you're going to be running the things on AC house current
anyway rather than on the original dynamotors in most installations,
it would be easier just to use an inexpensive 120V isolation transformer
driving a bridge rectifier and a pi filter as your power supply. Cheaper
to build than a high voltage supply and you get 168V out of it minus the
loss in the filter choke.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."