Another way to isolate the low voltage associated with the microcontroller and that portion of the circuit operating on higher voltages is by using an opto-isolator.relays can switch very high current loads, both AC and DC.
transistors can switch medium current loads, DC only (triacs can switch AC)
transistors switch very fast, relays switch very slow.
relays wear out after x amount of cycles, transistors can last longer than the technology itself.
transistors waste more power than a relay
So would there be any large problem with a relay or other device being switched on and off by a MCU powered with DC +5V to drive a device that runs on 120V AC?
by Aaron Carman
by Duane Benson
by Duane Benson