A very simple and useful SCR tester circuit diagram can be constructed using few external common electrical components . This schematic circuit diagram use just few resistors and a simple red LED .
The tested SCR will be connected to the k, A, G terminals ( cathode , anode and gate ) . By pressing the S1 switch a current will be delivered to the tested SCR which will be triggered on . If the SCR is good the LED 1 will glow once the gate is triggered with S1 , and remain lit indicating that the device is conducting . By pressing the S2 switch the LED should turn off and remain in this state .
Using this schematic circuit you can test other components like LEDs, triacs or diodes . When you test this types of components you need to connect the anode and cathode leads to the anode and cathode of the diode ( and the LED should glow ) . This tester electronic circuit diagram need to be powered using a 9 volts Dc power supply circuit or a 9 volts battery .