The circuit in this example uses a simple comparator circuit plus electrical time delay for the car reversing camera. Automobile manufacturers usually use the reversing light circuit to power the reversing observation camera. In an automatic transmission car, when switching from parking to driving (or from driving to parking), the gear shift will go through the reverse gear, at this time the camera will add a short voltage pulse. This sudden voltage pulse is not conducive to the sensitive circuit in the camera and may shorten its life. This example proposes a simple and inexpensive method that avoids this situation.
The circuit shown in the figure generates a 2s power supply delay for the car's reversing camera.
The input of this circuit is connected to the positive and negative terminals of the reversing light. The circuit supplies power to the camera through a MOSFET. R1 and C1 form a time delay element. When the reversing light is on, it slowly charges the capacitor through resistor R1. R3 and R4 form a voltage divider for setting the inverting end of the comparator to 6V. The moment the power is applied to the circuit, the comparator output is low and the MOSFET is turned off. When the voltage of C1 rises above 6V, the comparator output is high and the MOSFET is turned on. The values ​​of R1 and C1 set the delay time to 2.2 seconds. This time value can be calculated according to the charging time of the capacitor:
VC (t) = VIN & TImes; [1-e- (t / R1C1)],
6 = 12 & TImes; [1-e- (t / 33kΩ & TImes; 100μF)], and t = 2.287s
You can set different delay times by changing the value of R1 or C1. When the gear lever is switched from the reverse position to any other position, the capacitor C1 is discharged through D1, R3 and R4 within 60ms. When you switch between parking and driving, the gear lever passes the reverse position, because there is a 2s time delay, the camera will not be energized, so there will be no short voltage pulses, so it is conducive to the camera's sensitive circuit!
Mini Air Fryer,Best Mini Air Fryer,Air Fryer Without Oil,Best No Oil Air Fryer
Ningbo ATAP Electric Appliance Co.,Ltd , https://www.atap-airfryer.com