I have a simple relay circuit which consists of a 12v DC coil relay switching a 110v AC motor load. The relay is controlled by a pic through a ULN2803 Darlington array and there is also a 1N1004 diode across the relay coil to snub the flyback voltage from the coil.
The problem I have is when I switch the relay the AC load causes some sort of noise or interference which travels all the way back to the Pic and locks it up. This noise can happen both when I turn the motor on and when I turn the motor off. The motors are small 20 watt motors.
So what can I do to filter or suppress or eliminate this noise? What exactly is this noise?
One more thing, when I switch the relay with no AC load it works fine, it also works fine with resistive loads such as lights.
Thanks to all.
The problem I have is when I switch the relay the AC load causes some sort of noise or interference which travels all the way back to the Pic and locks it up. This noise can happen both when I turn the motor on and when I turn the motor off. The motors are small 20 watt motors.
So what can I do to filter or suppress or eliminate this noise? What exactly is this noise?
One more thing, when I switch the relay with no AC load it works fine, it also works fine with resistive loads such as lights.
Thanks to all.