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LED “Halogen” Lamp Circuit for Motorbike Headlamp

LED “Halogen” Lamp Circuit for Motorbike Headlamp

The post explains a simple 21 watt LED lamp circuit module which can be used as a direct replacement for a standard halogen lamp used in motorcycles headlamp.

LED vs Halogen Lamp

The proposed "halogen" LED lamp replacement module image can be seen below:


Conventional filament type halogen lamp is shown below:

The image at the top shows an example LED lamp replacement for a standard halogen bulb fitting shown below it.

With the easy and extensive availability of LEds, today it's quite possible to make any desired LED lamp module at home for replacing other forms of less efficient lamp options.

So here we'll discuss how to make the proposed halogen LED lamp replacement circuit. Let's learn the procedures:

Referring to the above image, we can see the LEDs are wired over 7 separate PCBs and then wired together to form one single module.

How to Assemble the Circuit

Each board can be seen with 3 LEDs each, constituting a total of 21 LEDs.

3nos LEDs are selected because the supply 12V available from the vehicle allows only 3nos to be connected in series, and series connection facilitates sharing the same current across the three LEDs.

Now since more than 3nos. of LEds cannot be accommodated in series, 7 such strings are connected in parallel with each other for achieving the desired 21 watts.

The above assembly must be done over a well designed heatsink cored glass epoxy PCB.

The entire configuration may be tightly fixed over an thick hexagonal aluminum cylindrical former or base to form the proposed halogen LED module unit. The aluminum will hep to sink the generated heat from the LEDs.

A Current Limiter is Essential

The above unit will strictly require a current controlled driver circuit which can be understood with the following points:

We once again take the help of the versatile LM338 IC for the required current control function.

Referring to the circuit diagram we ca see it in it's simplest current limiting mode. The LEDs consume around 2.5 amps together which is never allowed to exceed by the IC keeping the unit safe from the issue.

The above design can be upgraded with a Dimming option, as shown below:



Aluminum mount (for heatsink) or base design for fixing the LED PCB assembly


Efficiency Comparison between Motorcycle Halogen Lamp and LED Lamp

<<<<Output----------------Halogen Lamp--------LED Halogen Lamp>>>>

  • Nominal wattage----------55 watts-----------------------21 watts
  • Nominal voltage-----------12V----------------------------12V
  • Test voltage----------------13.2V--------------------------13.2V
  •  Color temperature -------3200K ------------------------6000K
  •  Luminous flux-------------1500lm------------------------2500lm




About the Author

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!

52 thoughts on “LED “Halogen” Lamp Circuit for Motorbike Headlamp”

  1. Hello, I have five 5w LEDs I'd like to use together. Each one has a voltage drop rating from 6-7 and forward current of 700ma. Can you help me decide which resistors I need? I'd like to use the dime option too.

    • I'll be making a device as the above but on a heat sink with a small fan. It's a regular 12v motorcycle battery so it'll range anywhere from 12-14 volts. Thank you 🙂

    • OK great, in that case you can try the first circuit from the above article, use one LED on each string, so you will 5 strings for the 5 LEDs.

      use 8 ohms 5 watt resistor in series with each of the LEDs, and use 0.35 ohms 5 watt resistor for the LM338 output resistor

    • You are welcome….If dimming option is required then you could opt for the second circuit, and use a 1 ohm 5 watt for the other resistor associated with the dimmer switch.

  2. ic LM338 hard to get so i want replace it with LM317,with LM338 we can wire 7nos and the question is how much nos of the leds when i use LM317?i need your help.thanks in advance.

  3. im wondering if there is a replacement part LM338, LM338 is difficult to get in where I live, more than 20 electronics store I was looking but they do not have. is there any substitute LM338 IC, and IC series what to replace, thanks in advance (sorry bad english,im using google translate)

  4. helo, i want to replace, bike 35w halogen bulb to 20w LED..What diode do i need to use, to make the bridge rectifier nd also the capacitor value for the same. thanks

  5. Hello sir,

    I am trying to bi-color LED (Warm and Glow) to change the color from warm to glow by using the dimmer circuit. That's different than changing the brightness by the dimmer.
    I gave an idea to do that but I need help here. My idea when you use the regular dimmer the warm LEDs will start light up until it get full brightness and the glow lEDs will be at full brightness and as you use the dimmer it will bright down until get OFF. Do you have any idea how i can achieve that.

    Thanks in advance,

    • Hello David,

      In simple words you want a dimmer circuit that can implement a smooth transition of the LED illumination from warm white to cool white and vice versa through the control of the dimmer circuit…. right?

  6. Sir thank u for reply, Sir can u please tell me the value of capacitors and bridge rectifier and after this what component used?

    • Syed, please specify the LED wattage, that will help me to figure out the bridge rating and also the capacitor value roughly….please remember that super capacitors are very costly…but are almost permanent

    • 0.45amps looks quite small for the headlights, it should be at least 2 amps, you can use 1N5408 diodes for the bridge rectifier and for the capacitors you can try 4 nos of 6800uF/25V in parallel,

  7. Sir meri ap se request hay k ap aisi led headlight circuit design karain motorcycle k liye jis ki roshni bohot tezz ho or wo without battery pe chalain bike ki power pe mere matlab hay k meri bike me abhi battery nahi hay laikin jb bike start hoti hay tu light on ho jati hay laikin wo shayad ac source hay or wo acceleration pe depend hay zyada acceleration ho gi tu zyada tezz light chalti hay please aisa kuch design karain

    • Syed, you can try using a bank of super-capacitors with the supply after rectification using a bridge rectifier, this will probably help the LEDs to produce a constant glow regardless of the motorcycle speed.

  8. Hello sir,
    I need your help i made a bike led bulb
    I installed 2 led of 20 waat and 3 led of 12 waat
    Please help me to design it's circuit because when we connect direct to battery it will turned on it will heat and fused after some time so give me correct circuit diagram please help me

  9. Swagatam you have shown 21 leds which are producing lumen between 1500-2500 lumen…if we calculate lumen per led it makes atleast 71 lumens for a single led….could you plz guide where to procure such high lumen led's and what is estimated price for them…..


  10. sir which led have to be use i mean led number, or can i use smd led 5730 with your resistor value. wating for your reply sir

  11. While connecting the LEDs in series it is important to see cathode and anode terminal, my question is that sequence of terminals really matters.?? Can I connect the LEDs in series in any manner without seeing the positive negative terminal?

    • yes for LEDs must be always connected by observing correct polarity especially when connected in series, even if a single LED is connected in reverse the whole array will remain shut off or may get damaged.

    • you'll have to include the high voltage isolating capacitor, rest of the components can be eliminated.

      make two 50 LED series and connect their opposite ends together, meaning the anode end of one series should be connected with the cathode end of the other series in both the ends.

      now simply connect one end of this assembly to one of the mains terminals while the other to the other mains terminal through a high voltage capacitor.

      the whole set up will be too dangerous to touch, exercise adequate caution.

  12. Thanks for ur prompt reply bt sir can we run the LEDs without the circuit by adding some ics to each led………. I want to run it direct on 230v AC without any circuit like festival series lamps

    • LEDs are different from filament bulbs, without capacitor the LEDs will start blowing off with slightest voltage fluctuations if connected directly or through resistors. therefore the recommended capacitive circuit has to be used with it.

  13. Sir actually I want to make 100 nos of led toran of 2 array each array of 50 leds I am trying to convert leds in AC bulbs like 6.2 v festival decoration lamps so that's my question sir

  14. Hello sir i am trying to make AC 1 watt bulb like 6.2 v 3 amp miniature lamp ……so it will be easy to solder led in series without seeing plus and minus of led so pls help ………..Thanks in Advance

  15. Hello sir i am trying to make AC 1 watt led bulb like 6.2 v 3 amp miniature lamp or festival decoration lamp so it will be easy to solder led without seeing plus and minus of leds so pls rpls ……and Thanks in advance

    • R = 20 – 3.3/0.9 = 18.55 ohm

      W = (20 – 3.3) x 0.9 = 15 watt

      please refer to the above specs…you'll need around 20 ohm, 15 watt resistor for the said implementation

  16. then could we wire 4 white leds per string in series with a 47 ohm resistor (for 8mm led 20 ma current, taking 14.5v batt voltage) looking for making led tail light. thanks.

  17. a fully charged battery will give around 13 v and when the vehicle is running the batt voltage varies from 13 v to 16 v (as most automotive dc regulators are capped at 16 v.) so can we wire up the leds without the limiting resistor and 4nos in series with lm 338 wired to deliver current a bit lesser than the total forward current of the leds?? thanks

    • for a single string it will do but when more parallel strings are involved individual resistors become necessary for uniform distribution of current through the strings.

  18. Hi all,
    Thank you very much for the shared information. I am planning to make a head lamp using the above circuit diagram. I want to make it with a dimmer circuit as shown in circuit no 2. I am fitting it on my Honda Unicorn. Unicorn draws power directly from the alternator. I will be using Philips 1 watt high performance LEDs. I have check the pinout diagram of LM 338 but there is no pin called Adj.
    1) What is Adj pin in IC 338?
    2) Can I draw power from the alternator or draw power from battery/
    3) I have learnt that a LED driver circuit is required to drive a cluster of LEDs. Is it true?
    Kindly revert asap,
    Thank you.

    • 1) check LM338 datasheet, you will get the correct pinout diagram in it.
      2) Power can be drawn from the alternator as long as it's connected with the battery also.
      3)The above design is a current controlled LED driver circuit.

  19. Hi Swagatam,
    Is there any way to make 1 W led driver using 12V DC? I mean atleast powering upto 10-12 LEDs in series, i have gone through your other driver circuits but I would like to power up more than 10-12 at a time, please let me know your thoughts and if possible, the circuit. Thanks in Advance.
    Rajthilak K

    • Hi Kapila,

      The above design does not include a Dimming feature, but it can be easily modified with that feature. It can be done by providing a higher value resistor selection option for reducing current input from the IC, for dimming the LEDs.

      I'll try to update it soon.

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