PIC and noise

[creative]

Hi friends,
I am using PIC 16f84a in a control board to drive a uln2805 and it drives 8 miniature relays and the relays drives heavy contactors of 50AMP. It's working smoothly without load in the final stage. when I do attach final load (heavy 3phase motor, AC solinoids, small singlephase motors) sometimes the PIC suddenly resets. found out the actual problem occurs because of spikes so I put snubber network(100ohm2w+0.1/1kv) to all the loads in parallel like Contactors, and across the contactor connections too. The problem has been solved 90% >But still sometimes the Pic resets itself when it switches any of the above item. I think it will be a good idea to solve the problem 100% to put a filter in the 12 ac supply of the PIC circuit. can you suggest any filter design to override noise of spike from the PIC suppy?. Which is better to add filter in DC or AC 12v?
appreciate your suggessions in advance,

 

[GraveYard_Killer]

Hi friends,
I am using PIC 16f84a in a control board to drive a uln2805 and it drives 8 miniature relays and the relays drives heavy contactors of 50AMP. It's working smoothly without load in the final stage. when I do attach final load (heavy 3phase motor, AC solinoids, small singlephase motors) sometimes the PIC suddenly resets. found out the actual problem occurs because of spikes so I put snubber network(100ohm2w+0.1/1kv) to all the loads in parallel like Contactors, and across the contactor connections too. The problem has been solved 90% >But still sometimes the Pic resets itself when it switches any of the above item. I think it will be a good idea to solve the problem 100% to put a filter in the 12 ac supply of the PIC circuit. can you suggest any filter design to override noise of spike from the PIC suppy?. Which is better to add filter in DC or AC 12v?
appreciate your suggessions in advance,

if its working without the load, flawlessly, i believe the problem is inrush current. u could expermiment by putting a 50amp NTC thermistor with the load motor.