One of the four answering group circuits

This circuit requires five relays and is relatively complex, but it has
functions such as sound and light display and violation detection.
    In the figure, the function of button SB6 is: when the specified time has expired and the moderator presses this button, its normally closed contact will disconnect the power supply of each
group so that they can no longer answer questions; at the same time, the normally open contact of SB6 will close . , connect the audio loop , indicating that the time is up.
After the host presses button SB7, the circuit is restored.