31 Jul
2025
31 Jul
'25
11:11 a.m.
On Wed, 16 Jul 2025, 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.
As I live in Australia I get 240VAC and 50Hz as opposed to the US 115VAC
and 60Hz.
Late input and FWIW. As taking care of the old pieces of equipment is
enough of a challenge by itself I try to reduce the distraction by using
modern and off-the-shelf lab support infrastructure components.
In this case I would just go for a proper power converter such as one
listed here: <https://www.amazon.com/dp/B09KVG9N71/> (not endorsing the
manufacturer, the product, or the web store in any way), having checked
that the power budget is sufficient of course, as this haven't been stated
for the machine in question. Also to keep the original system intact.
Maciej