Devantech multichannel relay module boards devantech usb rly16 the usb rly16 relay module board has 8x relays providing volt free contact relay outputs each with a current rating of up to 16a the processing hardware is powered and instructed from any standard usb bus and the power for the relays is via the 21mm dc power input adaptor with a power supply of 12v dc ge500ma required the relays are spco single pole change over types and the normally open normally closed and common pins a