Smart Vehicle Headlight Brightness Controller Circuit

The Smart Vehicle Headlight Brightness Controller Circuit is a cool electronic system designed for automobiles.

It automatically adjusts how bright the headlights are based on the surrounding light.

This awesome technology helps make driving more comfortable and safer especially when it gets dark or when you are driving through tunnels.

The circuit uses a photo-transistor, potentiometers, diode, relays and a simple audio amplifier transistor to check how bright the light is and switch between high beam and low beam headlights smoothly.

Circuit Working:

Parts List:

The circuit is set up to work with a 12V DC power supply which is its main energy source.

At the center of this system is a photo-transistor Q2 which is really important for detecting light and how bright it is.

There is also a transistor amplifier Q1 along with two relays named relay1 and relay2 plus some resistors and potentiometers that help adjust how sensitive the circuit is and when it operates.

The photo-transistor Q2 senses the light around it.

When the light gets brighter like during the day or when streetlights turn on Q2 lets more current pass through which lowers the base voltage of transistor Q1.

This Q1 transistor boosts the signal from Q2.

The current that flows through its collector decides if the relay1 and relay2 will turn on.

The resistor VR3 pot allows you to change the sensitivity of the circuit by affecting how Q1 is biased.

The relay1 and relay2 are SPDT types and they connect to the high beam and low beam circuits of a vehicles headlights.

When the light around is bright enough Q1 turns off which means relay1 and relay2 also turn off switching the headlights to low beam mode B and C is the common mode.

On the other hand, when the light gets dimmer Q1 turns on activating the relays and switching the headlights to high beam mode A.

The diode D1 helps keep things safe by letting the back EMF flow around the relay coil which protects transistor Q1 which works within safe voltage levels and helps it last longer.

Formulas:

Below mentioned are the formulas for designing a Smart Vehicle Headlight Brightness Controller Circuit:

To make the circuit work its best, you can figure out the needed resistance values and sensitivity by following these formulas:

Photo-transistor Current:

The photo-transistor Q2 operates based on the light intensity.

The current IQ2​ is proportional to the light level.

IQ2​ = L × S

where,

• L is the light intensity (lux)
• S is the sensitivity of the photo-transistor Q2

Transistor Base Voltage:

The base voltage VB​ of Q1 can be calculated as:

VB​ = IQ2​ × VR3

Relay Activation:

The relay operates when the collector current IC of Q1 exceeds the relays activation current.

IC​ = (VCC​ − VCE​ )/ R1

where,

• VCC​ is the supply voltage for 12V
• VCE is the voltage drop across Q1 from 0.2V for saturation

By adjusting the potentiometers VR1, VR2 and VR3 you can fine tune the sensitivity and transition points between high beam and low beam modes.

How to Build:

To build a Smart Vehicle Headlight Brightness Controller Circuit you need to follow the below mentioned steps for connections and assembling:

• Assemble all the components parts from the above mentioned circuit diagram
• Connect the collector of photo transistor Q2 to the base of transistor Q1.
• Connect the emitter of photo transistor Q2 to negative supply of 12V car battery.
• Connect the resistor R3 one end between collector Q2 and base of Q1 transistor and other end to one leg of VR3 pot and the other leg of VR3 pot to on leg of VR2 pot.
• Connect VR2 pot one leg to one leg of VR3 pot and other leg to one leg of VR1 pot as shown in circuit diagram.
• Connect pot VR1 one leg to one leg of VR2 pot and other leg of VR1 to negative supply of 12V car battery
• Connect the collector of transistor Q2 to the coil of relay1, connect base of transistor Q1 to collector of photo transistor Q2 and emitter of transistor Q2 to positive supply of 12V car battery.
• Connect cathode of a diode D1to collector of transistor Q1 and anode of D1 diode to negative supply of 12V car battery.
• Connect the GND pins of both relay1 and relay2 to negative supply of 12V car battery.
• Connect the NC contact pin of relay1 to coil pin of relay2
• Connect one end of S1 switch between pot VR3 and VR2 and other end of S1 switch to +12V car battery.

Conclusion:

The Smart Vehicle Headlight Brightness Controller Circuit is a useful feature in vehicles that automatically changes how bright the headlights are depending on the surrounding light.

This helps keep drivers safe and makes driving less tiring.

The system uses a photo-transistor and a basic relay which makes it affordable and simple to build.

By adjusting the potentiometers you can get exact control over how sensitive the lights are and when they turn on or off.

References:

Smart vehicle headlights control system