I bought a Trav-A-Dial from a fellow poster here. It's one of the ones
with a built in encoder. Southwestern Industries can't or won't tell
you what signals it outputs or what voltage it uses. With help from US
Digital and from Ned Simmons telling me how to use an oscilloscope to
watch the encoder working and google I have been successful in
figuring out how to hook up one of these. The operate from 5 volts. On
the unit I have the black wire is +5 volts and the white wire is GND.
The red and yelow wires are one pair of Nand and And outputs and the
violet and green wires are the other pair. The encoder disc has 250
lines on it. Using a digital readout from US Digital, #ED3, configured
to read in quadrature, will give the Trav-a-Dial .0001" resolution.
From the ED# connect the +5 volts to black, GND to white, channel A
to red and channel B to violet. Configure ithe ED3 so that one count
equals .0001 and that it counts in quadrature. You will now have a
..0001" resolution digital display from your Trav-A-Dial.
ERS