Scr Circuit Diagram. When the trigger input is high both transistors q2 pnp transistors and q1 pnp transistor will work. And can also test diode led and triac.
Another practical use for the scr in a dc circuit is as a crowbar device for overvoltage protection. This circuit works similar to an scr. A mercury in glass thermostat is used here which are supposed to be extremely sensitive to the changes in the temperature levels surrounding it.
The transistor lat as scr trigger.
We can know the location pin on the gate lead anode lead and cathode lead. It s a diode with a gate an scr not only conducts in one direction like any other diode but the gate allows the conduction itself to be cut on and off. It has three external terminals anode gate and cathode and uses the alternative symbols of figure 1 a and has the transistor equivalent circuit of figure 1 b figure 2 shows the basic way of using the scr as a dc switch with the anode positive relative to the cathode and the scr controlled via its gate. Pictured above is a silicon controlled rectifier scr or thyrister.
