Using a VMA436 8-Channel Relay Board and an Arduino Uno R3 along with an Adafruit Audio FX board. Trying to synchronize music to 110VAC lights. I am seeing some strange behavior that is related to load on the output side of the relays. I have the relay outputs wired to standard 110V power outlets. When I have nothing plugged into the outlets, the system works perfectly. When low load 110V lights are connected, it functions mostly without issues. However, when I plug in light fixtures that have a brick transformer light fixture on it to the outlets, it interrupts the arduino script and does not function at all. I know each relay is not even coming close to the 10A limit they have.
I feel like I am seeing effects of the opto and coil side of the relays both being powered by the arduino. Bouncing back at the arduino and causing it to reboot, etc. I have tried pulling off the jumper that comes on the VMA436 and powering the relay board across the VCC + GND with a 9VDC battery and connecting my arduino ground to the COM and inputs on the relay boards to the corresponding Digital Outputs of the arduino. This gave me consistent functionality as long as I did not use the light fixtures that have a brick transformer plug.
Any other suggestions to further isolate the arduino from bouncing and feedback from the relay board? I am also powering the audio fx board from the arduino power.