Trigger circuit composed of single junction transistors

1206RGB (single)

One-piece inductor

A trigger circuit composed of a single junction transistor is shown in the figure.
The lower part of the left picture shows the main circuit of the thyristor, and the upper part is the trigger circuit of the thyristor. They are all connected to the same power supply. Therefore, the AC voltages of these two parts are zero-crossing at the same time in the alternating process. The transformer used is called a synchronous transformer.