Thyristor type answering circuit three

It is a dual -timing answering circuit, and the number of channels can be increased at will. It uses 555 time base integrated circuits Ai and
Az to form two sets of delay circuits. It uses 7806 three-terminal fixed integrated voltage regulator A3 as the working power supply of the circuit. Bl uses a 3V
instant intermittent buzzer ; Bz uses a small buzzer. device . Adjust the potentiometers RP and RP2 to change the delay time of the two sets of delay
circuits respectively .