I have 4 12V(1A) solenoids running on a 12V(4.16A) power supply. Each solenoid circuit is controlled by a 5V relay module connected to the Arduino Uno (powered by USB).
The solenoids actuate properly but eventually the Arduino resets, typically when multiple solenoids are turned on/off in fast succession. This is accompanied by random character artifacts on the LCD display (connected to the Uno) during operation but before the reset.
From what I've gathered there are back EMF surges occurring when the solenoids lose their charge. Here are some possible remedies I've found:
-Add a flyback diode (IN4004) to each solenoid circuit. (Redirect the surge)
-Add a capacitor (4700 - 10,000 uF) to the 5v supply (from the Uno) for the relays. (Filter the surge)
-Provide a separate 5v power source to the relay modules instead of using power from the Uno. (Isolate the surge)
Any input on which solution(s) should be applied or other possible causes for the Uno reset and LCD distortion is appreciated.