• Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Get free circuit help 24/7

New Projects | Privacy Policy | About us | Contact | Disclaimer | Copyright | Videos | Circuits for Beginners | Basic Circuits | Hobby Projects | Transistor Circuits | LED Drivers 

You are here: Home / Car and Motorcycle / Self Adjusting Automobile Headlamp Circuit

Self Adjusting Automobile Headlamp Circuit

Last Updated on November 8, 2021 by Swagatam 4 Comments

caution electricity can be dangerous

A suddenly dimming and brightening automobile headlamp is usually quite undesirable, since it causes a painful interference with the normal vision of the opposite side driver or the passengers.

In this post we try to design a gradually self-adjusting automobile headlamp brightness circuit, which enables the brightness of the vehicle headlamp to vary proportionately in response to the ambient light conditions, and also to the headlamp intensity of the opposite vehicles.

Dimmer/Dipper vs Auto-Adjusting Headlamp

In a conventional automatic dimmer/dipper types of headlamp controller circuit, the head lights are switched with two different filaments or intensity levels. One of the lamp filaments is a low power filament which provides the dipping/dimming effect, or reduction of the lamp intensity, while the other set of filaments are rated at higher power for providing the normal, high intensity on the headlamp brightness.

Although these circuits work well and fulfill the intended lamp brightness control in response to the light beam from the opposite side vehicle headlamps, the relatively rapid switching of the headlamps causes severe strain on the drivers eyes, which may sometimes lead to a hazardous situation.

In contrast, a self-adjusting headlamp dipper appears to be rather useful, which enables the headlamps to gradually adjust the lamp intensity, depending on the brightness of the lamp of the opposite vehicle, and also the lights from the street lamps and other sources.

This concept utilizes a PWM controlled MOSFET circuit instead of relay switching. Let's learn the working in details.

How the Circuit Works

Please add a 100uF capacitor across pin3 of IC3 741 and ground, in order to ensure a soft response on the headlamp light adjustments

The basic idea is to increase the pulse width at the MOSFET gate and the brightness of the headlamp, when there's lower illumination on the LDR, and vice versa.

The entire circuit could be divided into 4 stages, 1) Light detector, 2) Voltage Follower, 3) Astable Oscillator, 4) PWM Controller.

The left side IC1 555 is configured as a square wave oscillator, which feeds the sample square wave to the pin#2 of the right side IC2 555 circuit which is configured as a PWM generator.

The PWM generator IC 555 transforms the square wave frequency into triangle waves and compares it with the voltage level applied at its pin#5.

The pin#5 of the right side IC2 555 stage is applied with the varying voltage due to the varying light levels on the LDR. This is implemented via the IC3 op amp buffer stage in the following manner.

The potential at the junction of the LDR and the 1M/2M2 resistors increase or decrease depending on the light level on the LDR, coming from the opposite side vehicle.

This varying potential difference is amplified and buffered by the voltage follower circuit using IC 741, whose output is then applied at in#5 of IC2 for the necessary PWM correction.

This instantaneous LDR varying levels applied on pin#5 of IC2 are compared with its triangle waves, which generates a proportionately varying PWM on pin#3 of IC2.

When the light on the LDR gets brighter, it causes the PWMs to become thinner proportionately, and when the light on the LDR gets dimmer, the PWM gets wider proportionately.

This oppositely varying PWM effect in turn causes the headlamp to get dimmer when light on the LDR is brighter, and dimmer when the light on the LDR is brighter.

Thus, depending on the light intensity on the LDR, the headlamp brightness self-adjusts, such that its brightness increases when the light on the LDR is low, and it gradually becomes dimmer as the light intensity on the LDR gets higher.

The 2M2 pot helps the user to set the maximum and the minimum headlight intensities with respect to the LDR illumination levels.

You'll also like:

  • 1.  Motorcycle Regulator, Rectifier Tester Circuit
  • 2.  Sequential Bar Graph Turn Light Indicator Circuit for Car
  • 3.  Car Speed Limit Warning Indicator Circuit
  • 4.  Car Turn Signal Flasher Circuit with Lamp Malfunction Indicator
  • 5.  Simple Capacitive Discharge Ignition (CDI) Circuit
  • 6.  How to Make a Bicycle Horn Circuit with Ringtone

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

Reader Interactions

Comments

    Have Questions? Please post your comments below for quick replies! Comments should be related to the above artcile Cancel reply

    Your email address will not be published. Required fields are marked *

  1. Mohammed hussain khan says

    November 11, 2021

    Thanks a lot sir very nice circuit
    Very useful thanks again

    Reply
    • Swagatam says

      November 11, 2021

      You are welcome Mohammed!

      Reply
  2. manojkumar tamilnadu says

    November 10, 2021

    hello swagatam.. suggest a circuit to replace common 12V BCU electronics with minimum voltage & minimum wires to operate basic functions of a motorcycle like tuning signals, indicators, multitoned warning sounds, brake light etc

    Reply
    • Swagatam says

      November 10, 2021

      Hello Manojkumar, please explain your requirement in more details, if possible I will try to figure it out….

      Reply

Primary Sidebar

Calculators

  • 3-Phase Power (15)
  • 324 IC Circuits (19)
  • 4017 IC Circuits (52)
  • 4060 IC Circuits (25)
  • 555 IC Circuits (98)
  • 741 IC Circuits (19)
  • Arduino Engineering Projects (83)
  • Audio and Amplifier Projects (114)
  • Battery Chargers (82)
  • Car and Motorcycle (94)
  • Datasheets (46)
  • Decorative Lighting (Diwali, Christmas) (33)
  • Electronic Components (100)
  • Electronic Devices and Circuit Theory (36)
  • Electronics Tutorial (116)
  • Fish Aquarium (5)
  • Free Energy (34)
  • Fun Projects (13)
  • GSM Projects (9)
  • Health Related (20)
  • Heater Controllers (29)
  • Home Electrical Circuits (102)
  • How to Articles (20)
  • Incubator Related (6)
  • Industrial Electronics (28)
  • Infrared (IR) (40)
  • Inverter Circuits (98)
  • Laser Projects (12)
  • LED and Light Effect (93)
  • LM317/LM338 (21)
  • LM3915 IC (25)
  • Meters and Testers (65)
  • Mini Projects (148)
  • Motor Controller (67)
  • MPPT (7)
  • Oscillator Circuits (26)
  • PIR (Passive Infrared) (8)
  • Power Electronics (34)
  • Power Supply Circuits (77)
  • Radio Circuits (10)
  • Remote Control (48)
  • Security and Alarm (61)
  • Sensors and Detectors (120)
  • SG3525 IC (5)
  • Simple Circuits (75)
  • SMPS (29)
  • Solar Controllers (60)
  • Timer and Delay Relay (53)
  • TL494 IC (5)
  • Transformerless Power Supply (8)
  • Transmitter Circuits (40)
  • Ultrasonic Projects (16)
  • Water Level Controller (45)

Calculators

  • AWG to Millimeter Converter
  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Small Signal Transistor(BJT) and Diode Quick Datasheet
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator

© 2023 · Swagatam Innovations