The circuit is composed of a monostable delay circuit, a driving circuit, a buzzer, a light emitting diode and the like. The output signal of the one-shot delay circuit consisting of 555 and R1, C3 controls the operation of the latter circuit.
After the lamp is turned on, the power from the directional lamp relay in the circuit is applied to the 555 8 pin through the diode, so that the capacitor C3 is charged through R1. As the charging progresses, the potential of the 6-pin rises. When the potential of the 6-pin reaches 2/3 VDD (approximately 1 minute delay), 555 flips, and the low level of the 3-pin output turns BG on. The corresponding LED is illuminated, and the buzzer sounds, and the sound and light signal reminds the driver to turn off the light in time.
The length of time in which the lamp is lit in the circuit corresponds to the delay time of the circuit, which can be changed by adjusting the time constant R1C3.
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