The motor vehicle headlight auto-dimming controller 5

Published:2011/8/1 2:49:00 Author:Ecco | Keyword: motor vehicle, headlight, auto-dimming , controller | From:SeekIC

The motor vehicle headlight auto-dimming controller described in the example can automatically change the high beam into low beam at night, it improves the safety of driving at night.The working principle.The vehicle headlight auto-dimming controller circuit consists of photoresistor RG, electronic switch IC, potentiometer Rp, resistor R, the relay K, diode VD and other components, the circuit is shown as the figure 7-5. Turning on the headlamp control switch S, RG is in a high impedance state due to no light exposure, the pin 2 of IC is in high potential, their internal electronic switch is off, pin 4 outputs high potential, K is in free state, the normally open contact is open, normally closed contact is connected, high beam EL2 is lit. R chooses 1/2W metal film resistor or carbon film resistors. RP selects small organic solid potentiometer. RG uses a photosensitive resistor with light resistancebeing less than or equal to lOkΩ, dark resistancebeing greater than 5OOkΩ. VD uses lN4007 silicon rectifier diode. IC selects TWH8751 high-power electronic switching circuit. K selects a l2V or 24V (supply voltage is according to motor vehicle) small DC relay.



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