The circuit described here can be built and used in your vehicle for an automatic dipping and dimming operation of the vehicle headlamps, in response to the intense lights coming from an opposite vehicle headlamps.
Why an Automatic Headlight Dimmer/Dipper is so Important in Vehicles
You must have come across this irritating situation while driving at night when you find the headlight lamp focus from an opposite vehicle coming straight to your eyes, making things difficult to assess, and giving rise to a situation of a collision or a possible accident.
Incidentally, the driver of the opposite vehicle might be going through the same situation due to the headlight focus from your vehicle.
Such situations are normally tackled by using manual dipper switch mechanism, where the driver is prompted to "dip" the focus of his headlight, thus giving the opposite vehicle a chance to adjust his vehicle and also an indication that he too needs to "dip" his vehicle lamps.
However, doing the above operation manually, every now and then can become horribly laborious and troublesome, therefore if some kind of automatic system is Incorporated, can help to save this headache of the driver, especially while he is driving in stressful conditions and on dangerous highways.
Simulation and Working
The following diagram describes a simple yet effective auto head lamp dipper or dimmer circuit. The transistor is used as a comparator, which compares the preset resistance level and the LDR resistance level with reference to ground.
Circuit Diagram
How the LDR Operates
Light falling over the LDR from the headlight of the vehicle coming from the front instantly lowers its resistance and allows more current to flow to the base of the transistor.
The transistor conducts and activates the relay, which in turn flips the contacts such that the host vehicle's headlamps gets connected with the dipper filament, changing its intensity.
The whole circuit may be enclosed in a small box and installed somewhere near the driver's dashboard area, however the LDR needs to be wired and placed out of the enclosure, in some corner of the wind shield, so that it is able to "see' the light from the opposite vehicles just as the driver would see them.
Parts List
R1 = 1K,
P1 = 10 K,
LDR = With resistance @ around 10 to 50 K when illuminated in daylight (under shade).
T1 = BC547,
D1 = 1N4007
Relay = coil 400 Ohms, DPDT, 12 volts
Making a vehicle dimmer/dipper without Relay
The above automatic dipper circuit can be modified for operating with mosfets:
Dimmer Dipper with Cellphone Charger
The following brief explanation was provided by Miss Surya for getting a better view of the proposed circuit design of an automobile dimmer/dipper head light switch circuit with an optional cell phone charger circuit for facilitating the charging of a cell phone also on board.
Simulation and Working
Here the IC 555 has been used not as a charging indicator rather as a comparator for controlling the dipping action of the head lamps.
The use if IC 555 as a charging indicator would have made the circuit unnecessarily complicated, therefore a novel and simpler way is selected for the charging ON indication.
The LED connected across the 5 Ohm watt current limiting resistor effectively indicates the charging status of the cell phone and switches OFF the moment the charging process stops.
The IC 555 works like a comprartor here, when light falls on the LDR, voltage at PIN#2 rises above the set internal threshold which prompts the IC to change its output PIN#3 voltage from 0 to 12, triggering the connected relay.
The relay contacts immediately transfer the positive supply from the "high" filament to the "low" filament of the head lamps, resulting in an instant dipping of the lamp intensity.
The LDR must be positioned in such a way that it only receives light rays coming from front of the vehicle, which will be mostly the lights from another vehicle's head lamps.
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MOHAMED Reswan says
I would like to have a detailed circuit design using relay…
rezdude07@gmail.com
Jinu says
May be two vehicles have headlight with different intensity .like 2 car uses two types of light one is led and other is halogen in this situation is it possible
Swag says
the circuit will respond to all forms of light, it doesn’t matter whether it is from LED or halogen….
Jinu says
Pls help to do dis idea for our project
Swag says
what is your question?
Jinu says
We r try to do this idea as our project so pls help and support
Amal Vijayan says
Sir could you please explain the working of mosfets in the circuit…
and what is the use of 100 K resistor between 5 and 7 terminal of ic555
Give the complete details about this circuit
Email: iamamalvijayan9597@gmail.com
Swagatam says
Amal, the mosfets are configured to act like SPDT switches, when the right side mosfet pair is ON, the left side pair is off and vice versa.
the 100K is to create some hysteresis effect between the ON OFF switching
Anonymous says
How to avoid street light beam and how to differentiate Street light beam and the beam of Opposite Car as LDR senses light from surrounding.Is there any photoconductive sensor other than LDR which we can use to build this ckt and avoid street light beam intenisty.
Mail id:mrinalini022@gmail.com
Swagatam says
place the LDR inside a short pipe, such that only light beams coming from the front is able to reach the LDR, and no other light from around or top.
LDR and photosensor will behave in the same manner, the correct way is to put the sensor inside a pipe like enclosure
Anirudh Madhav Kakkad says
Can i install this automatic dipper in a scooter?
Swagatam says
yes you can
Mohammad says
Arduino version is possible, I have already built it…
Swagatam says
Mohammad, please send me the details in my email: admin @ homemade-circuits.com
surya virat Molugu says
Muhammad can u plz forward it to me!! My email is moluguvirat@gmail.com Thank u
surya virat Molugu says
Hello sir, can you please post a circuit of AUTOMATIC HIGH BEAM TO LOW BEAM HEADLIGHT USING ARDUINO. with components required!! plz help me.
Swagatam says
Hello Surya, if possible I'll try to produce it in my website
surya virat Molugu says
Sir try to produce as soon as possible. Thank you sir.
surya virat Molugu says
Sir I'm in a need of ur ckt diagram with components to complete my project. My last date of submission is Oct 21st. So please reply me with the complete details of it, as soon as possible sir. Plz sir. Thank you
Swagatam says
Surya, all the details are given in the article, please click the diagram to enlarge.
you can write the details on paper and show it to the part dealer he will do the needful
Swagatam says
….sorry the arduino version will not be possible…
Sri Dhar says
What type battery and bulb should be used while submitting as an mini project sir pls kindly requesting u to answer me its urgent
Swagatam says
For a realistic look you may want to procure an actual car headlight lamp with double filament, however if you find it difficult then you may simulate the same by tying two small DC bulbs together and wire them up as shown in the first diagram.
The Dim bulb could be a 24V bulb and the bright bulb could be a 12V bulb…
Swagatam says
power could be from a 12V /1amp ac dc adapter
Mohammad says
Hi . Im trying to build automatic headlight beam by using arduino mega 2560 to program the circuit diagram, i want to know if anyone can help me for a clear circuit diagram (12v input)or the connection i mean how to connect arduino to the circuit diagram
Swagatam says
if possible we'll try to get it and post it for you
gv rahul says
we have connected potentiometer in the 1st circuit,so how much of resistance to be applied
Swagatam says
R1 can be replaced with a 1M pot.
gv rahul says
what is the use of potentiometer in auto dipper circuit
Vivek G says
hi sir ,
can you send me the circuit diagram for automatic head lamp control using micro controller please
RTR says
Sir can you please post a circuit for an automatic wiper
Anonymous says
Hi,
I was going through your blog on "How to Make an Automatic Vehicle Headlight Dipper/Dimmer Circuit". I have few questions regarding this.
1. Is this circuit available in any vehicle launched/launching in India as a standard functionality?
2. Do we need to have this circuit installed in both the vehicles(travelling in opposite directions)to have the proper result?
Please let me know
Swagatam says
Hi,
I am not sure about it's availability in the market.
The circuit responds to lights from the headlamp of opposite vehicle, so it's not required for the other vehicle to have the same circuit installed.
shubham says
Shubham
can we combine the ckt of automatic headlights on/off with the ckt of automatic dimmer/dipper
pls help me
shubham says
can the ckt of automatic headlight on/off be combined with the ckt of automatic headlight dipper/dimmer
pls hep its urgent
Swagatam says
I did not understand your question, please specify your exact requirement.
Santhosh says
Hello Sir,
I wanted to make this circuit . I got all the components but at local electrical store only 12 V 200 ohm 2 amps DPDT relay is available . Can this be used ? If not please provide a circuit which uses transistors as switches .
Swagatam says
Hello Santosh,
Using transistor will make the configuration very complex and lengthy, try the relay that you have bought, I think it might just work.
Santhosh says
I will try Sir . I want to know what is the difference between ordinary relay and DPDT relay and also can you give information about pin outs of DPDT relay . What will be its cost ??
Swagatam says
Normally a relay consists of a two fixed contacts and one moving pole, it's also called a SPDT relay….DPDT relays have a pair of them, meaning two SPDT in one package, but with a single coil.
for more info you may refer to the following article:
https://homemade-circuits.com/2012/01/how-to-understand-and-use-relay-in.html
Santhosh says
Hello Sir ,
My car headlamps are rated at 12V 5A 60W , so I cannot use the relay of 2A I bought . Sir please provide a circuit using Mosfets or power transistors as switches . My friends told me that by combining light activated and dark activated switch ,dimmer/dipper is possible . Will it work ?
Swagatam says
Hello Santhosh,
I have posted it above, pls check it.
Santhosh says
Thanks for the circuit Sir , Can you tell me which IC is used in the circuit and Mosfets to be used for 5 A output ??
Swagatam says
you can try IRF9540n mosfet, IC is 555
litu says
Sir I need circuit diagram for MOSFET based inverter and Mosfet Based Chopper. Both different circuits. Sir could you please provide me the same.It is urgent.
Thank You.
Swagatam says
Inverter circuit:
https://homemade-circuits.com/2012/09/mini-50-watt-mosfet-inverter-circuit.html
Chopper circuit:
https://homemade-circuits.com/2013/03/how-to-convert-12v-dc-to-220v-ac-using.html
Zaib says
Will you please let me know the use of this variable resistor in this circuit?? Today I assembled all the parts on Breadboard and it successfully worked. Thank you. 🙂
Swagatam says
it's for adjusting the sensitivity of the circuit to light.
Zaib says
And please let me know fullform of T1 and P1
Swagatam says
T1 is a transistor and P1 is a preset or a variable resistor.
Zaib says
Thank you very much dude
Zaib says
Hello Swagatam. Well please will you let me know whats this LDR??? And how does it work? If i assemble all these components on a PCB will it work? Please help me out dude.
Swagatam says
Hello Zaib,
LDR is a light dependent resistor whose resistance lowers in response to increasing ambient light.
Yes this circuit is correct and will work if done correctly.
Zaib says
Sir I stay in Pune. & soon there is going to be a Dipex compitition. I have chosen this topic of upper & dipper headlights. Please will you let me know how much will it cost me to make it. & duration of it. Thankyou
Swagatam says
The cost will be around Rs.100/-, making time would depend on your knowledge and efficiency….
Puneet says
Alright thanks for your time,
Where can i buy this product from seems very interesting to me
I want to fit it in my vehicle
regards
Swagatam says
You mean the shown spare parts?
You can buy them from any electronic component dealer.
Puneet says
I mean the full fledged assembly. I am not a very skilled person to assemble spare parts so if you could suggest from where i could buy the entire assembly
Swagatam says
I am not very sure about that, probably you can get it from any 4-wheeler auto spare part/accessory dealer.
Puneet says
Swagtam, may i please talk to you regarding auto dipper?
Please share your phone number
Puneet
Swagatam says
Hi Puneet,
You can feel free to ask your questions here, I'll answer them all.
Syambabu Babu says
dear sir,i have done the circuit given in your blog ELECTRONIC DIPPER,can you give me a detailed report on that circuit to make that as our final year project?pls explain the working of relay and the CE configuration
Swagatam says
I have explained everything in the later half of the article, you may elaborate it a little more as per your convenience.
surya s says
if we are using a 1M pot,whether any other modifications needed in the circuit?
Swagatam says
No modifications will be required, adjust it properly so that it makes the circuit respond at the desired light levels.
surya s says
we are using .0047 uf. but the circuit is not working sir
Swagatam says
It is not so critical, has no direct effect on circuit functioning.
surya s says
we have given everything in the right manner sir,sir,the capacitor 4.7 k means?
Swagatam says
It is equal to 0.0047uF, you may use a 0.01uF instead.
surya s says
sir,when the -ve and =ve legs of the leds are shotted,they are emitting light,what is happening sir,
Swagatam says
Red LEDs require less voltage to light while white leds require more voltage…that's why the difference.
If you are using white LEDs use only two in series.
Swagatam says
pin3 is not connected to ground, it's connected to the leds via the resistor.
Shravan Kumar says
hi surya can u plz mail me the whole project report asap am an btech ece student am doing dis as my project i kindly request u 2 send me d total info u have abt this project plz plz plz plz plz
surya s says
pin 3 of ic is not connected to the -ve voltage,right sir?
surya s says
sir,i know that i am disturbing you…sorry sir,we are new to the field of electronics in practical circuits.sir,we got the circuit dimmer in the above link.It worked 2 days ago.But today when i replaced the same circuit,even the led s are not showing brightness.We cant trace out the problem with it sir,i have changed all the components,we have only a limited period,our guide too is not that much aware of these circuits.sir,please can you suggest me a solution..we are going to construct this circuit too with the relay,for a project of comparison,kindly please help us sir
Swagatam says
Hi Surya,
The IC555 will blow-of only if the supply voltage exceeds 16 volts and the LEDs will blow-of if they are without any resistor.
So check the above things, is the supply voltage right? and are the LEDs in series with the shown resistor?
Swagatam says
also connect pin4 of the IC to positive
surya s says
thank you sir
surya s says
thank you sir,thank you very much..whether the circuit needs any modifications?
Swagatam says
As far as I think, no modifications should be required in the given circuit design.
Regards.
surya s says
thank you sir,thank you very much
Swagatam says
Replace the pot with a 470K or 1M resistor, meaning connect this resistor across pin 2 and ground, then it will respond to torch light also.
The LEDs which light up in dark will obviously correspond to bright LEDs and vice versa.
The first LED is just for indicating power supply ON/OFF.
surya s says
thank u sir,wil check it
surya s says
thank you sir,please post it as soon as possible…
srujana says
sir can u help us in geting d circuit design nd design specifications for the circuit
is it possible to have a total project report
Shravan Kumar says
can u help me in getting the above circuits design specifications?
plz if possible send me the pdf file of the project
Swagatam says
I can guide you through the building process, but I cannot make the project report for you.
The circuit is too simple, just procure the listed parts, solder them on the general PCB……that's all it will start working.
Unknown says
which bulb is use for this..
surya s says
SIR,the circuit is similiar to the above in its applications,it should dim and bright with help of LDR and IC 555…along with it it should charge the mobile meanwhile….sir,please,can you help me?
Swagatam says
Today I have some spare time in the evening so I will try to complete the design, and publish it as a new article.
I'll inform you when it's done.
austin sabu says
sir i just want to make the model of an autommatic dimming system in a dummy car. how could this be possible?
Swagatam says
austin,
In the second 555 circuit do the following changes:
remove all the transistors and the pin3 100k resistor.
now connect white LEDs across positive and pin3, and pin3 to ground
use 10k series resistors for the ground LED and 1k for the positive LED
that's it, now the LEDs will respond like dipper lights
surya s says
sir,its a bit urgent.can you please post ittoday itself?
surya s says
sir,can you post a ckt of electronic auto dipper cum mobile charger using 555 and 9 v input?
Swagatam says
Hi Surya,
Explain the application and other details more elaborately, only then I would be able to figure out an appropriate circuit.
Shravan Kumar says
sir can u help me with the circuit design please. if possible can i have d total project pdf
Anonymous says
Wow rude!
gv rahul says
Sir will u tell us how to make connections