In the reset there was a 1uF electrolitic capacitor and I added .1 uF cap in parallel. With this one, the stability was almost perfect. I guess that the spikes where of higher frequency and the 1uF didn't absorb them. .1 uF in parallel with the 220uF electrolitic capacitor in the input of the= 7812 .1 uF in the on the voltage input of the pic (directly over the pins) This last two helped a little but in more than 24 hours of working I have no resets. Next time I will use the osciloscope to see whats going on. Thanks Russell for all On Thu, Mar 18, 2010 at 9:47 AM, Russell McMahon wrot= e: >> All what I did was change the cap on the reset pin, > > >From what value to what value? > >> and put another cap on the spare >> voltage input of the pic. > > which changed it from what value to what value? > >> By now, every thing works fine. >> Thanks a lot for all your comments. > > BUT it sounds like you MAY have changed it from marginally unstable to > marginally stable. > ie, you should have adequate capacitors there BUT a small value should > be enough. > > It seems likely that a spike was getting into you power supply and > that you have damped it down enough "for now". Understanding what was > happening (and probably still is) is essential if you want good > reliability. > > An oscilloscope on the 7805 input and output should prove of value. > IF you are getting a significant spike there then the diode > arrangement you are using (on the PCB) is probably acting like you'd > expect that it might. > > Trying changing the caps back and putting diodes across the actual > relay coils (if they are not there already as well as where they are > shown on the PCB) may be educational. > > Fixing something is good. Knowing what was wrong and how the 'fix' > worked is better. > > > > =A0Russell > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- = Matias Vidoni eMail: matiasvidoni@mvcom.com.ar MSN Messenger: matiasvidoni@mvcom.com.ar Skype: matiasvidoni WWW: http://www.matiasvidoni.com.ar Google Talk: matiasvidoni@gmail.com -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist