We often see many car drivers, to forgot to turn off lights in a car when parking. Then, they back to start the machine, it did not work. Because a battery does not has a energy.
Do you want it to happen to you? This Headlight Warning buzzer circuit can help you. It will alert you! If…
- Switch it off the start SW
- Close the car door But turn on headlights in the car
The working of circuits
Headlight Warning buzzer circuit diagram
In the circuit, Two transistors Q1 and Q2 are an astable multivibrator circuit. The collector of the Q2 connects to a loudspeaker to be a load of the circuit.
The capacitors C1, C2, and resistors R3, R4 are timing section and to set a frequency of output signal.
First of all, we turn on the light switch. Then, the electric currents come to diode-D1 and a resistor-R1. It is the positive voltage power supply of this circuit. Next, some currents flow to ZD1-9.1V zener diode. It keeps the voltage across ZD1 to provide a constant 9 volts.
The ground wire connects to the door switch to the cabin light. Which is controlled by the door. This switch will connect to the ground, just when the door open only.
Suppose that we turn off the start switch and turn on headlights up. Then the driver opens the door. The Oscillator generator circuit will work. The buzzer produces a loud tone at a frequency of about 1500 Hertz. It will alert us forgot to turn off the light in the car.
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