Sound source switching circuit composed of thyristor

Audio source switching circuit composed of thyristor introduces a thyristor audio source switching circuit that does not use integrated circuits, does not occupy relay contacts, has simple circuits and is easy to expand. When the power is turned on, because the control poles of SCR1--SCR4 have no trigger current and are in the off state, J1--J4 do not act. If you need J1 to pull in, press S1, the current will charge C1 through R2, point A will become low potential to the ground, and T1 will be cut off. As C1 is charged, the potential at point B increases as the potential at point A increases. At this time, since the current charging C1 flows through the control electrode of SCR1, SCR1 is turned on, J1 is powered on, and LED1 lights up. After S1 is released, J1 remains in the pull-in state due to the action of SCR1, and C1 passes through R1 Discharge. If you need J4 to close, you need to press S4. Since T1 is turned off first and then turned on, SCR1 is turned off due to power loss, J1 is reset, and then SCR4 is turned on and J4 is closed. The principle is as mentioned above. In the same way, if you need other relays to close, just press the corresponding button. If you need to expand, you only need to add unit circuits composed of light-emitting tubes, relays, thyristors and buttons.