Solid State Relay – Common

This is a DC controlled Solid State Relay which can turn 230V AC equipment on and off. The output is like a NO normally open contacts of a relay and have to be in series with the Load like any other switch. This should not be used for large inductive loads like big motors. The Q1 transistor limits the current thru the LED by providing an alternate path for more current. The DC input can be from 3V to 20V.

The Triac can be chosen depending on current in the load. Look for datasheets and applications at STMicroelectronics for BTA41600 triacs. MOC3041 zero crossover opto-diacs.

Read more at my main page – Solid State Relays – SSR I used to make them long ago.

This is the newer version of NO – Normally Open DC Control SSR. It has a Constant current source that is more stable and robust.

DC-AC Solid State Relay or SSR – del30008

You could use it to control AC powered Electricals like Heaters, Motors and Fans. It can also be used to Switch ON and OFF any Equipment, Control Panel or System.

You have to choose the correct current rating and heatsink needs of Triac. This is the older version below. It has a shunt current control. This new circuit above has a regulated current source.

This is a basic output Module in control systems. It is faster than Electromagnetic relays but has some heating in the triac. Some designs with mosfets are also available. SSR with a IGBT – Insulated Gate Bipolar Transistors also can be made for large powers.