Semiconductor relays and TRIAC based
mains controlling ( 20 ) :
Semiconductor relay circuits
Charge coupled bi-directional power MOSFET relay - uses an
inexpensive C-MOS inverter package and a few small capacitors
to drive two power MOS transistors from a 12v to 15v supply,
only about 1.5mA of DC is needed to turn on and off 400 watts
of AC or DC power to a load, leakage current from the power
line into the control circuit is a tiny 4uA, pdf file
Electronic Relay - medium power complementary transistor
pai will switch on and off a load up to 3A 12V