Relays and Microcontroller reset issue

ljcox said:

I have attached an extract from my Garage door opener circuit for your information.

Note that the R & C values need to be selected according to the load characteristics.

Click to expand...

Really appreciate everyone help. The relay module i built was quite open to all type of load switching. Should I really put this RC network into the design? I believe the resistor rating should be at least more then 2W.

You need to design an RC network to suit the load.

Note that the primary reason for the RC is to prevent errosion of the relay contacts due to arcing. The resetting is a secondary consideration.

The resistors in my garage door opener are 500 mW since the current is small due to the capacitive reactance at 50 Hz.

I noticed that the input to your 12 volt regulator is only 10.77 volts -- 9.94 out. You also stated you had a switching supply so I'm thinking you have DC in, 2 diode drops from the bridge. Not sure if it is the problem but the relays probably don't pull in real good. Seems like you can get rid of the bridge and the 12 volt regulator and the whole power system might "stiffen" up.

The solution

Dear all,

I think that i have the solution.please all try this solution and give me the feedback.In market there is an ac connector with EMI filter this solves the problem.and there is anther thing but i think it is not effective you can but a diode in series with the transistor.