Dual timing multiplexer circuit

Circuit working principle: The dotted box in the upper right corner of the figure represents
the operation box of each competition team. Now assume that the first group presses the answer button, AN01, and it is pressed.
The 7.8 V voltage passes through LED 2 and VD, causing VS01 to trigger conduction, causing H01, H1 and LED 01
to all light up. Since there is a voltage drop of about 4V across H1 and R1, HA1 rings immediately. In addition,
since the voltage at both ends of the IED2 and VD1 components is less than 4V at this time, it is impossible to
trigger other thyristors to conduct again.