This is a Normally Closed PCB Mount SSR. That means when DC
Control input is low, the triac is ON, the output passes the
load current to turn on small heater-motor-lamp or a bigger
One of the applications is in Home Automation -
When input DC is high the output is OFF. This is also Optically Isolated from Mains. A Microcontroller output which is buffered by some driver can drive this relay.
It is better that in big systems these SSR Modules can be on another PCB, to avoid mains wiring near Logic circuits. But this cannot be used for medical electronics, or critical applications. More reliability and visual isolation of voltages may be required for such equipment.
A Post of mine listing a SSR Manufacturer Continental Industries - Solid State Relays
Connect this SSR In Series With Load, Like a Switch, Q2 Triac
can be BT136, TXC 10K40, TIC206D. 230V AC 2A Contact Rating or
The resistors R2 and R1 may have to suit the beta of Q1 and
also the type of triac. R1 should be many times R4 for
opto to work. So if you select other components then redo
design of R1-R4.
10th Jun 2020
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