I had the oposite, in the bench it did not work and on the final prototype it did! I used separate boards, one for the logic and other for the relays that were activated by NPN transistors +12V | RL | C logic >---->>---1KR-----B signal conector E | GND Francisco Martin Peach wrote: >I have had this kind of problem and no amount of diodes in any configuration >helped. Finally I shielded the PIC with metal and that did the trick. The >EMF seems to have been radiated inside the box. >/\/\/\/*=Martin > >----- Original Message ----- >From: "Daryl Sayers" >To: >Sent: Monday, February 18, 2002 5:19 PM >Subject: [EE] Power spikes reseting my pic > > >>I have built a simple watering system using a PIC 1684. Works well on the >>test bench but am having problems running live. >> >>I am using a 24V power pack (1A). The 24v is to power the solenoids to >>open/close the water valve. I then cut this 24v down to 12v via a 7812 >>to power the 12 relays that I use to activate the solenoids. I then >>use a 7805 to get 5v to power the control circuitry. >> >>My problem is that I seem to be getting spikes (back EMF) into my >>control circuitry that is reseting my PIC. I have put a diode across >>each solenoid to limit the spike but this doesnt seem to be enough. >>I put the diodes inside the box I built. Should I put something >>right across the solenoid itself. I was thinking a filter cap. What >>sort of cap and what value should I use. >> >> >> >> 12v 24v >> | | >> | | >>RA1-4 |\ ULM2803 | >> -----| \---------+ | >> | / | | >> |/ O -----+ >> O \ >> Relay O ------+-------------//-------------+ >> | | O >> | --- Long Cable O solenoid >> | /\ Diode +---//-------------+ >> | -- | >> | | | >> | | | >> GND ----+---------+---------+ >> >> >> 12v >> | >>24V +--------+ | +--------+ 5v to pic etc >>--------| 7812 |--+---| 7805 |------- >> +--------+ +--------+ | >> | | | >> | | |+ >> | | --- 200uf >> | | --- >> | | | >> | | | >> | | | >> GND ----+---------------+--------+ >> >>-- >>Daryl Sayers >>Corinthian Engineering Ph: (02) 9906 7866 >>Suite 19, 401 Pacific Hwy Fax: (02) 9906 1556 >>Artarmon, NSW, 2064 email: daryl@ci.com.au >>Australia www: >> >http://www.cordoors.com.au > >>-- >>http://www.piclist.com hint: The PICList is archived three different >>ways. See http://www.piclist.com/#archives for details. >> >> > >-- >http://www.piclist.com hint: The PICList is archived three different >ways. See http://www.piclist.com/#archives for details. > > > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body