"w. v. ooijen / f. hanneman" wrote: > > > Will a ULN 2803 (8 darlington drivers) protect its inputs from back-EMF? > > In the case of a PIC driving a 2803 which drives the stepper motor coils, > > is there any danger of hurting the pic? > > A 2803 has bleeder diodes to the Vcc, which is the only function of the Vcc > pin. Don't forget to connect it, otherwise things will work normally but > only for a short time. The bleeder diodes protect the 2803, the circuit > driving the 2803 won't notice any spikes. See my comments on this in one of the other posts. > > > Should I stick a 0.1uF or <what value> uF cap on each of the 4 PIC pins? Never put more than 50pF *directly* on a PIC output - read the PIC specs carefully. This may caus e latch-up. If you really want to (but I can't see why), add a series resistor in first. -- Friendly Regards /"\ \ / Tjaart van der Walt X ASCII RIBBON CAMPAIGN mailto:tjaart@wasp.co.za / \ AGAINST HTML MAIL |--------------------------------------------------| | Cellpoint Systems SA | | http://www.cellpt.com | |--------------------------------------------------| | http://www.wasp.co.za/~tjaart/index.html | |Voice: +27-(0)11-622-8686 Fax: +27-(0)11-622-8973| | WGS-84 : 26�10.52'S 28�06.19'E | |--------------------------------------------------|