4 channel relay board


i bought a 4 channel relay board and hooked it up to my arduino. Anything seems to work fine, i can switch the relay on and off and on…

When a high voltage device is connected (my desk light 230v) it is working (connected to com + NC) but when i switch the relay off the light turns off and my arduino gets disconnected from usb and reconnects. Do the relay needs more current for switching high voltage circuits? Vcc and Jd-Vcc is connected so the arduino supplies the power to switch (USB 400ma should be enough…)

My relay board is working with 5v and can switch high voltage (230v 10A) and there seems to be anything needed builtin (diode, resistor,…)

So whats the problem here?

Thanks for help!

Do the relay needs more current for switching high voltage circuits?

Relays really need their own coil power supply and not be powered from the arduino.

Put a varistor on the AC side of each relay. I ran into this issue as well when controlling AC Pumps. Your getting a voltage spike for the light being turned off, which is causing the Arduino to crash/reboot.

I also recommend a separate power supply for the relays as well. Granted I seen the same issue, with a separate power supply too. The varistor will most likely solve the problem.

Your relay board has optical isolation available. If you're powering it separately from the Arduino it should be very difficult for a spike from the pumps to affect the Arduino.

See http://arduino-info.wikispaces.com/ArduinoPower#OI