On 2025-07-16 8:57 a.m., ben via cctalk wrote:
On 2025-07-16 8:13 a.m., Tom Hunter via cctalk wrote:
Recently I got a nice and complete PDP-8/s from the US. The power supply
uses a ferroresonant transformer which in addition to the standard
primary
and secondary windings has a separate 2.3H winding connected in
series to a
2uF 660VAC capacitor forming a resonant "tank" circuit. The
transformer's
secondary side and the resonant circuit are operated in saturation.
There
is a magnetic shunt to prevent the primary side going into saturation as
well. It accepts a wide input voltage range, but is very sensitive to
the
input frequency of 60Hz. This is quite a nice if not elegant design
for the
period in question, but maybe not the most efficient.
A 50 hz to 12? volt DC and 12? volt DC to 60 hz converter might be a
better option if you have moving parts, plus you have safe power supply.
Have you checked for a UK pdp 8 power supply schematic?
Ben.
Exactly what I do to change motor speeds on my jukeboxes - convert the
line to 12VDC, then use an Inverter for automobiles, etc, that puts out
120 @ 60 Hz at the current required. I then modify the converter output
frequency if I want to speed up or slow down the synchronous motor speed...
John :-#)#
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