hello , I hope all is well.
i made a circuit recently which the arduino triggers (relays and leds from its digital outs) I built and tested the circuit on a work top table using a standard 5v power supply to test and trigger the relay/led circuits (to save me booting up my pc+arduino each day). The circuit works great but when i finally connected the arduino instead of the 5v psu, The earth's/grounds of the circuit and arduino just do not like each other...So I installed an opto-isolator circuit between each and wow it all works !! great, but the problem is that when i installed it all into a metal chassis the usb plug and the power plugs both touch the chassis and cause the same problem as before, so what i did was use insulation tape around the usb connector, this just seems so bad and not a good idea.
i think its a ground loop problem,potential difference or something? i just hope someone might know of a fix that will work, I have no schematic because my circuit is so hard to see now under all the hook up wires. if anyone might know of a fix i'd be so grateful
thanks for reading.
: )