27-08-2015, 11:09 AM
i need a circuit regarding the automatic parking light for cars
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circuit for automatic car parking light
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i need a circuit regarding the automatic parking light for cars
31-03-2017, 11:45 AM
This circuit uses a simple LDR to detect incident light from the vehicle. It was paired with a single variable resistor RV1 to form a voltage divider which supplies the bias voltage for the transistor. The transistor was used as a switch here to activate / deactivate the relay connected with it. The relay in turn will be used to turn on a lamp or any high power light connected to it.
The circuit can be operated in Auto and Manual mode, where an SPDT switch was used to toggle the mode. When the Auto mode is selected, the transistor will be used as the switch that will be controlled by the pair LDR and RV1. This pair automatically turns the transistor and turn the relay when light is incident on it. Meanwhile, in Manual mode, a simple switch was used to turn the relay on and off.
Now to set the previous circuit, the LDR must be exposed to the Vehicle Light in the dark and set RV1 until the relay is turned on. This causes the potential divider section to provide bias voltage to the transistor only when the vehicle light is incident on it and this causes the relay to ON at the same instant.
This parking light switch with LDR automatically turns on the light when the surrounding light is dimmed to a preset level. The first circuit diagram is an NPN design designed for a negative grounded chassis. The second diagram is the PNP version intended for a positive grounded chassis.
The current level at which the circuit is activated is set via the potentiometer P1.
The layout of the printed circuit board can be used for both the negative and positive polarity chassis. Take into account that transistors and different for each type of chassis. The connectors labeled on the part placement diagram have the following connections:
P = Live car power
C = Car chassis
B = Park light bulb
Parking Light Switch:
![[Image: automatic-light-switch-positive-chassis-ground.gif]](http://www.electroschematics.com/wp-content/uploads/2010/07/automatic-light-switch-positive-chassis-ground.gif)
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