Hi, I am using Arduino Mega 2560. So far there have been no problems with the relay. I use a 4 channel relay as shown below. Each realy switches a solenoid valve (12 V). The continuous current is 0.6 A. I have fly back diodes about 5 cm to each solenoid valve, before entering the relay I also have fly back diodes (5 cm away from the relay). I did not use the solenoid valves for about 2 months and the relay did not switch. The relay is powered from its own 5 V source (optocoupler use). Only the control wires are connected between the Arduino and the relay and one 5 V wire from Arduino. 12 V was applied to the relay output for 2 whole months (but the relay did not switch all the time - there was no need). After 2 months, I put the solenoid valves back on and I wanted to turn them on... 4 control pulses were applied to the relay... but only one realy switched... all 4 diodes on the relay module was ON... I found that when I tap the relay a little, it switched.... Sometimes it switches itself... and sometimes it is necessary to tap.. it is not just one relay, they fool alternately.
Are the contacts tanned? Or is there some small current in the control wires? Thank you for the advice.
