Just for information - because a Stepper motor acts as a generator when rotated it makes a good low cost quadrature encoder for jogging inputs. Take a 200 step motor from a old 5 1/4 inch floppy, one opamp, some diodes and a few resistors and you have a a rotary jogging device. Turning that shaft produces a voltage, the voltage is applified, and the output is quadratured encoded. We drive the stepper motor with a quadrature encoded voltage to make it turn. Just reverse the process, turning the shaft by hand produces a voltage that is quadrature encoded.
Turbocnc has inputs for jogging Channel A and Channel B thats works very nicely with this circuit. To make the jogging circuit work just a little bit better I have tied the quadrature outputs of my stepper motor to a PIC12C508 first. I have coded the PIC so that if you turn the jogging input quickly it outputs a fast jogging pulse stream. Turn the shaft slowly and it outputs a slower stream. This makes fast turns of the shaft mean jog fast and slow moves of the shaft mean jog slow. Your PC's mouse does the same thing when you move it around.  |