"David Billington" wrote in message
...
Grumpy wrote:
"Jon Elson" wrote in message
...

DoN. Nichols wrote:


Looking at the wires, and assuming that ground is carried by the
shield, while the red is likely the power to drive the LEDs -- also out
of period with the packaged circuits, which were from the 1950s IIRC.

No, these packaged things look so much like Sprague parts, made in the
mid-late 60's, just before integrated circuits took over. The rest of
that module DOES look newer than that, however.

But, the MAGnescale is magnetic, so there would be no LEDs. It has a
smooth
stainless rod with SOMETHING inside.



I think you'll find that the SOMETHING'S inside are precision ground
bearing balls.

there is a British manufacturer who still makes them like that. They were
fearured in "Model Enginners Workshop"
a year or two ago




Newall http://www.newall.co.uk/index.php


Yes. that's the one.