In article ,
Jon Elson wrote:

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. There is an
excitation coil and two pickup coils, so the
signal scheme is exactly like a resolver or
inductosyn. You excite with a sine wave at some
modest frequency like 400 Hz, and as the head is
moved, the signal on each pickup coil rises, falls
and then reverses polarity with respect to the
excitation. The two coils pick up this signal in
quadrature. The converter box interpolates the
signal to increase resolution.

The patent literature will tell you a lot. Look for patents assigned to "Sony
Magnescale". There are ~30 such patents, some with relevant-sounding titles.

http://www.patentstorm.us/assignee-patents/_Sony_Magnescale_Inc_/44718/1.html

Google Patents is a convenient place to search, but be aware that patent
drawings on google are often mangled. If so, use http://www.pat2pdf.org to
get an unmangled copy.


I don't think that Magnescale and Newell encoders work the same way, even though
both are "magnetic".

Joe Gwinn