Based on some schematics I've found on the 7 x 12 minilathe yahoo groups, I can say this interface will definitively work on the original mini-lathe spindle speed controller. A more accurate schematics (or someone willing to mail me his/her minilathe controller, as a loaner for a few days, in order to reverse-enginneer it) will help and I will continue my search for it.

kreutz