4 Channel 5V Opto Isolated Relay Module is a simple relay board. 4 channel relay board works from a 5V supply to JVCC for the relays and 0V for the switching signal to activate relays . It uses a transistor to drive the relay & optocoupler is used to separate the output. Using this relay board you can easily control high power DC 30V/AC 250V devices or appliances using arduino or microcontroller. It can be connected directly to a microcontroller pin. It has 3 pin terminals each relay output NO COM NC. NO normally open with relay common pin. NC Normally connected with common.
What is the basic difference between normal and opto isolated relay module?