Thanks Al, I figured out the circuit myself but I guess there are many ways to do the same thing if you know what you are doing. I was interested in your link to see how they made a jogger but the link seems to be dead. Anyways here is a PDF of my circuit. Pretty straightforward. Any voltage generated by the stepper is clipped by the diodes, amplified and output on Quadrature A and B. The negative input of the opamps are biased midway of the +5 volt power supply. C5 is just a small filter. You can tie the quadrature lines A and B directly to the lines defined by TurboCNC for Jogger channel A and B. I process Quadrature A and B with a PIC12C508 before feeding it to TurboCNC. I use a Unipolar stepper for the input but a 6 wire motor works fine as well. For a unipolar motor the common ties to my J8 pin 5. Winding A goes to pin 1, winding B to pin 2. For a 6 wire bipolar motor tie Winding A+ to 1, A- to 2 and the common of A+ and A- to 5. To help with the jog cogging I also tied my Unipolar motor winding A and D together. This gives a more positive feel when turning the motor.
The part values are quite arbitrary. The 3K9 can easily be anything from 1K to 10K as long as they are the same. The opamp is probably the most widely used general purpose device but any single supply opamp could be used.
Experiment and have fun. |