I have the circuit on my DIY stepper driver board, I'll post the schematic once I do a cut and paste of the appropriate page and figure out how to attach a PDF file in the forum.
The BOM (Bill of materials)
1 - opamp LM358 about the cheapest the DIY can find but any opamp will do
4 - 1N4148 diodes
6 - 3K9 1/4 W resistors
2 - 1M 1/4 W resistors
1 - 10 uf 10 volt electolytic cap
alternatively you can use a LM392 comparator then the BOM would be
1 - LM392
4 - 1N4148 diodes
8 - 3K9 1/4 W resistors
1 - 10 uf 10 volt electolytic cap
The PIC is not required and is only used to condition the quadrature signal to make it into STEP and DIR or do what I did and have an acceleration function like your PC's mouse.
BTW ESjaavik I have completed my chopper controller design and built a few proto PCB's. I drive my 8 amp / phase test stepper motors at 35 volts and 8 microsteps. Max. Pulse rate from TurboCNC is set to 19200 equating to 720 RPM. To get to a higher step rate and RPM I need to use a higher voltage. The FETS I am using are only 50 volt rated so I can't go to a higher voltage until I change them which I probably won't do. 720 RPM equates to 144 ipm and with a planned table length of 24 inches it is fast enough.  |