DiscoLitez | Hardware / SSR

8-bit Solid State Relay circuit

Using Solid State Relays What is a solid-state relay? This is a device that switches AC power on/off depending on a small input signal, in this case, from a computer. This signal is totally isolated (optically) from the mains, so no damage can be done to your computer.

To get circuits to build your own solid state relays, see Tomi Engdahl's Electronic Pages.

Very important: The relay must be a 5V signal one - otherwise when you wire it up, it'll develop a smoking habit. ;-)

This circuit is designed for the IBM printer port. If you prefer it, put some resistors between the data out pins on the printer port. These should be 500R to 4K7 in value. Note that they are not included on the circuit, as they did not seem necessary for me.