16 Jul
2025
16 Jul
'25
3:42 p.m.
On Wed, 2025-07-16 at 11:42 -0400, Will Cooke via cctalk wrote:
The Computer History Museum in Sunnyvale, CA has a working IBM 1401
computer from Germany. It has ferroresonant power supplies. They bought
a converter to supply 50 Hz power because they were certain it wouldn't
work at 60 Hz. And it has motors in the card reader, card punch,
printer, and tape drives, that would all run at the wrong speed using
60 Hz power.
At first they had an antique and unreliable motor-generator. Now they
have a switching supply that IBM provided (maybe donated).
On 07/16/2025 11:10 AM EDT Tony Duell via
cctalk
<cctalk(a)classiccmp.org> wrote:
On Wed, Jul 16, 2025 at 4:00 PM Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
One thing to keep in mind is that the transformer may not be designed
to work at 50 Hz. A "normal" transformer will saturate if the
frequency is too low. A lot of 60Hz equipment won't work (well) on
50 Hz unless the transformer is specifically designed for that.
However, how that applies to a transformer that is already intended
to saturate I don't know. I do suspect it is still an issue since it
will likely saturate sooner than expected, for some definition of
sooner.
What I might do is make up a cap bank that is 1.2 X larger
than the 2 uF and power it up.
Remember that the resonant frequency goes as 1/sqrt(L*C). So
doesn't
that mean you want a capacitor of 1.2^2 times the original value?
-tony
Will