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Make this DRL (Day Time Running Light) for Your Car

The presented circuit of a DRL or a Day Time Running Light was requested by Mr.Senthil. Let's understand the complete design.

Technical Requirements

Hello Sir,

I'm an avid DIYer. Recently, i was looking to make a DRL(daytime running light) for my car using 1 watt smd LEDs.

But i couldn't find an appropriate circuit for my need. I want to drive Eight 1watt LEDs from my car battery.

I would very much appreciate if you could design a simple and rugged circuit to drive 8 x 1watt leds from a 12-14v input.

I'm also planning to add a heat-sink to dissipate any heat generated by the leds.
Thanks & Regards,

The Design

What's a DRL or Day Time Running Light Device:

A DRL is a safety car lighting device specifically assigned to moving vehicles for increasing the conspicuity of the vehicle during day time, especially when the daylight is accompanied with fog or during dull overcast days.It is normally fixed just beside the headlamps on either sides.

Normally a DRL system is in the form of constantly illuminated high intensity lamp. With the advent of modern High intensity LEDs, making a DRL lamp is matter of  less than  an hour.

As per the request the proposed day time running light or DRL circuit would be in the following form:

 DRL (Day Time Running Light) Circuit for Your Car

However in case you are interested to spice up the above idea a bit, and think that the system should do justice to the name that it has been specified, you would want to make it a literally "running" or chasing kinda thing!

Making a Chasing DRL Circuit

The DRL circuit discussed below shows how we can add a running effect to the above design and make it further interesting.

The circuit is actually a straightforward powerful LED light chaser circuit which is able to drive many 1 watt LeDs in a sequential manner.

The IC 4017 is a Johnsons Decade counter which generates a sequential switching at its 10 outputs in response to positive pulses fed at its pin#14. These pulses are referred to as clock signals.

As can be seen in the given circuit diagram, the IC 555 is configured in its basic astable multivibrator mode, and generates the required clocks for the IC 4017.

The clock pulses are taken from pin#3 of the IC555 and fed to pin#14 of IC4017.

In response to the above clocks, the output of the IC 4017 shifts a high logic sequence from pin#3 to pin#6. The moment it reaches pin#6, the sequence reverts to pin#3 and the cycle repeats.

Since only 8 LEDs are requested, pin#9 is connected to the reset pin of the IC so that the only 8 outputs become active with the required functions.

The speed at which this sequence may "run" or "chase" will depend on the setting of the 100k pot. Any value between 1 to 5 Hz may be set by suitably adjusting the pot.

The transistors respond to the sequencing high pulses at their bases and switch ON the connected 1 watt LEDs in the same pattern creating a powerful dazzling "running" LED light effect.

Since the illumination is very powerful, would become visible even during daytime and on foggy days and thus the circuit becomes very suitable as a DRL unit and may be used in cars as a Day Time Running Light device.

Running Chasing DRL (Day Time Running Light) Circuit for Your Car

Chasing Dark Spot LED DRL Circuit

For creating a "running dark spot effect" use PNP transistors in place of the NPN ones, connect the emitters to the positive, and connect the LEDs across the collectors and ground. Do not forget to reverse the LED polarity too.

Need Help? Please leave a comment, I'll get back soon with a reply!


  1. I am looking for a circuit to dim some LED Day Time Running lights, whilst the indicator is flashing. ie Full brighness when indicator is OFF(not flashing) and 50% brightness but on constant while indicator is flashing. like with Audis.


    No Indicator(not flashing) = LED DRL on full brightness
    Indicator flashing = DRL LED on 50% brightness. DRL LED's must not flash.
    If headlight is on DRL LED on 50% brightness. DRL LED's must not flash.

    DRL = Day Time Running Lights.

    Can you assist?

  2. you can do it in this way:

    Use a relay with a 470uF/25V cap connected parallel to its coil.

    Connect resistors at it N/O and N/C.

    Make the free ends of the resistors common and connect with the respective DRL positive string.

    Connect the pole of the relay with supply(+).

    Connect the coil terminal which has (+) of the 470u with two 1N4007 diodes cathodes (cathodes made common).

    Connect the free diode anodes, one with the flasher output (+) and the other with the headlight (+).

    connect the other coil/cap end and the DRL negative to ground.

    Select the resistors such that, position N/C produces 100% glow while N/O produces 50% of that.

  3. Hi Swagtam Sir
    Im a hobbyist. Looking for a driver circuit for 8 x 0.5W SMD LED for DRL.
    Can you please suggest me which value of resistor I use?

    Thanks in advance
    Waiting for ur reply sir.
    Ajay Sehgal

  4. Hi Ajay,

    You can try the second circuit from the following link, you will need to calculate the resistors correctly as per the given formulas

  5. try this one:

  6. Dear sir I have accurate current controlled circuit which is used in audi,BMW, benz for long life of LED's. I used this circuit since 2 years as a my bike headlights and DRL in my car. Same lighting since 2 years. I copy it from audi drl. It's work 3 led s in series and can run any of need. Just need some resistors, transistor, mosfet with heat sink

  7. You will have to do the following steps:

    Take a 12V relay, connect its coil one end to negative supply.
    Connect its other terminal to the headlamp switch positive output, so that now whenever head light is switched ON, the relay also activates closing its N/O contacts.

    Now just simply you have wire the above relays N/C contact and pole, with the DRL and the tail lamp such that the DRL and the taillight lamps get their ground or negative suppies via the N/C contacts.

    It means only as long as the above relay is in a non-activated mode, the DRL and the taillight would get access to the negative supply for switching ON, the moment the relay is activated the DRL and the taillights would be cut off from the negative ;line and will no longer be able to illuminate.

  8. Hi Swagatam.

    I would like to build circuit with HID 2x35W and DRL led 2x8 (each 1W). HID running at dark and LED diodes at day, could be ambient light sensitive.

    The lights will work just with key in ignition (keysense +6V).


  9. Hi Swags, do you have a schematic you can produce for this?

  10. Hi Rob, surely I can do it.

    Would you mind sending a brief write-up explaining the above functions elaborately as per your understanding. The longer the better;)

    It would help me to add a content with the schematic.

  11. Hi Swags,
    I'll try and explain in more detail. I want a module which will connect to a set of aftermarket DRLs that will allow them to turn on when the cars ignition is on (ideally via direct battery connection with a voltage sensor to turn them on but if not via ignition live feed). The module needs to connect to the headlight so that when it is turned on the DRLs dim to 50%. The module also needs to dim the DRLs when the indicator is activated on that particular side of the car (right DRL dims when right indicator is turned on etc.). This aspect isn't necessary when the headlights are on as the DRLs are already dim. When the indicators turn off I would like the DRL to fade back to full brightness say over a period of 2 seconds or similar.
    It is basically just like the new Audi DRLs which are built into their headlights.

    I hope this is enough information for you to produce a schematic but if not I can try and give you some more information. Also, using your relay method would be best!



  12. Hi Rob,

    That'll do, I'll try to design it soon and post it for you, please do keep in touch for the update.


  13. Will do...looking forward to it!

  14. Rob, I have published it here:

  15. Vlad, here's the design:

  16. thank you in advance
    kind regards,'

  17. Hi sir,
    I would like to build a brake lamp project using 1 watt high power leds, consisting of 12-15 leds.
    the leds would light on dim praking lights and would light full on brake pedal press. kindly provide me a circuit..
    kind regards,

  18. Hi Awan, I'll try to post it soon, keep in touch until then

  19. sir, you can also provide a second circuit using 0.5watt leds.

  20. yes you can use 0.5 watt leds also

  21. sure, i will be waiting for the circuit design, thanks

  22. thanks, appreciate your patience, will do it soon.

  23. Hi Mr. Swagatam, Can i please have the circuit design.
    regards, Awan

  24. Hi Awan,

    Please check it out, I have posted the design here:

  25. hi sir, in the first circuit, how did you come up with the value of the resistor ie 0.39ohms 1w.regards

  26. hi matheka, I used the following formula:

    R = (Us - LEDv)/LED amp

    Us = 13.5V or 14v

    LEDv = 3.3 x 4 = 13.2

    LED amp = 0.3

  27. HI I have a similar design as the first schematic but only 6 LEDs per site (Left/Richt). However my leds are 1 Watt high power LED (3,4-3,6 Vf and 300-350mA If). I would like to use the 10,8 - 13,8V battery from my car and use these as my DRL.

    What kind of schematic would I need to create?

    Thanks for your help.

  28. you can make two strings of 3 LEDs each...with a 8 ohm 1 watt resistor with each string...then you can put these two strings in parallel on each channel

    make sure the LEDs are mounted on heatsinks

  29. Thanks. I did my maths too. Came to same conclusion.

    One additional note: what do I need to do if the signal that I have is a PWM signal instead of 12v on/off. Can I use this with the same schematic? I can add another wire from the battery 12v but would like to use this drl signal which will originate from the board control module.

    Thanks again.

  30. If the PWM current is adequately rated then it may be directly fed to the DRL lamps via the switch, if the PWM input is weak, then you might need a transistor driver in the middle.

    you can do it using a TIP127 transistor...connect its collector to the DRL, emitter to the 12V positive through the DRL switch....and the base can be connected with the PWM input via a 10k resistor.

  31. Dear Sir,what if I would drive 100 Incandescent lights to make a running light?
    Will the Chip 4017,have another version that has Many Outputs up to 100...
    Or I will just have to reconfigure the pins to make it perform up 100?
    Should I just use a relay to power the incandescent from the mains?

    Thank You Very Much Sir!

  32. Dear Jordan, The IC 4017 has only one version with 10 you may have to put the lamps in parallel for implementing 100 bulbs

    you will need to use triacs for operating the bulbs as shown in the second circuit below:

    but this circuit is designed to produce a to-and-fro or a reverse forward kind of chasing effect

  33. Respected sir,
    In first circuit Can i used to 8mm? instead of 1 watt, led

    8mm led specification Color: White
    8 " mm "Straw Hat 0.75 watt

  34. Can you give me a reliable automatic water control with auto shutdown water pump and automatic street light controller circuit from your web site? Used for home purpose
    Thank you sir

  35. yes satheesh, you can use 8mm LEDs in the first circuit

  36. Satheesh, please search it using the search box, you will be able to find a good range to choose from

  37. Dear sir
    Please help me In first circuit i have used smd5730 led type 3.2 to 3.4 volt 0.5watt 150mAhIt. Exactly how much will unite resistor

  38. Dear Rajkumar,
    assuming the input to be 14V and the number of LED = 4, the value of the resistor will be
    14 - (3.3 x 4) / 0.15 = 5.33 ohms
    wattage = 0.8 x 0.15 = a 1/4 watt will do.

  39. Dear sir.
    I got it right now. Thank you very clearly explained to me

  40. Hello Sir! Thanks for all your contribution to the common knowledge of mankind! You provided great ideas/examples! I came to your site in search for a voltage-stabilized circuit so that the LEDs are neither overdriven nor underutilized, when operated from the cars 12-14V. Do you have something in your mind/archive? :) Thanks a lot!

  41. Thanks Balogh, you can try the following two concepts for safeguarding the LEDs optimally:

  42. Thank you! Now I got the final push to go buy some stuff and start playing around! :) Thanks again! Time to blow some parts up, the kids are gonna enjoy this! Gotta buy some protective glasses, too, I guess... :D

  43. All the best to you Balogh! and keep your fingers crossed ;D

  44. Hi,
    I could not correctly understand your need, do you need a LED controller circuit which would allow you to dim the DRLs or switch them OFF??

  45. hi,

    i want make DRL circuit for car , 9w/12v lead, 5 LEDs each side. please help me with circuit diagram.

  46. hi, connect the 5 LEDs in parallel with each LED having a series 2 ohm 1 watt resistor...connect the ends of this parallel connection with the battery through the DRL switch.


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