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5 Easy 1 Watt LED Driver Circuits

5 Easy 1 Watt LED Driver Circuits

1) Small 1 watt SMPS LED Driver

In the first design which is the most recommended one, we study an SMPS LED driver circuit which can be used for driving high watt LEDs rated anywhere between 1 watt LED upto 12 watts. It can be directly driven from any domestic 220V AC or 120V AC mains outlets.


The first design explains a small non isolated SMPS design, which is very accurate, safe and easy to build circuit. Let's learn the details.

Main Features

The proposed smps LED driver circuit is extremely versatile and specifically suited for driving high watt LEDs.

However being a non-isolated topology does not provide safety from electric shocks at the LED side of the circuit.

Apart from the above drawback, the circuit is flawless and is virtually protected from all possible mains surge related dangers.

Although a non-isolated configuration may look a bit undesirable, it relieves the constructor from winding complex primary/secondary sections on E-cores, since the transformer here is replaced with a couple of simple ferrite drum type of chokes.

The main component here responsible for the execution of all the features is the IC VIPer22A from ST microelectronics, which has been specifically designed for such small transformerless compact 1 watt LED driver applications.

Circuit Diagram

1 watt LED driver circuit SMPS

Image Courtesy: © STMicroelectronics - All rights reserved

Circuit Operation

The circuit functioning of this 1 watt to 12 watt LED driver can be understood as given under:

The input mains 220V or 120V AC is half wave rectified by D1 and C1.

C1 along with the inductor L0 and C2 constitute a pie filter network for cancelling EMI disturbances.

D1 should be preferably replaced with two diodes in series for sustaining the 2kv spikes bursts generated by C1 and C2.

R10 ensures some level of surge protection and acts like a fuse during catastrophic situations.

As can be seen in the above circuit diagram, the voltage across C2 is applied to the internal mosfet drain of the IC at pin5 to pin8.

An inbuilt constant current source of the VIPer IC delivers a 1mA current to pin4 of the IC which is also the Vdd pin of the IC.

At about 14.5V at Vdd, the current sources gets switched OFF and forces the IC circuitry into an oscillatory mode or initiates pulsing of the IC.

The components Dz, C4 and D8 become the circuit regulation network, where D8 charges C4 to the peak voltage in the freewheeling period and when D5 is forward biased.

During the above actions, the source or the reference of the IC is set to about 1V below ground.

For a comprehensive info about the circuit details of the 1 watt to 12 watt LED driver, please go through the following pdf document presented by ST microelectronics.

2) Using Transformerless Capacitive Power Supply

The next 1 watt LED driver explained below shows how to build a few simple 220 V or 110 V operated 1 watt LED driver circuit,that would cost you not more 1/2 a dollar, excluding the LED of course.

I have already discussed capacitive type of power supply in a couple posts, like in LED tube light circuit and in a transformerless power supply circuit, the present circuit also utilizes the same concept for driving the proposed 1 watt LED.

Circuit Operation

In the circuit diagram we see a very simple capacitive power supply circuit for driving a 1 watt LED, which may be understood with the following points.

The 1uF/400V capacitor at the input forms the heart of the circuit and functions as the main current limiter component of the circuit. The current limiting function makes sure that the voltage applied to the LED never exceeds the required safe level.

However high voltage capacitors have one serious issue, these do not restrict or are not able to inhibit the initial switch ON mains power in rush, which can be fatal for any electronic circuit LEDs are no exceptions.
Adding a 56 Ohm resistor at the input helps to introduce some damage control measures, but still it alone cannot do the complete safeguarding of the involved electronics.

An MOV would certainly do, also what about a thermistor? Yep, a thermistor would also be a welcome proposition.
But these are relatively at the costlier side and we are discussing a cheap version for the proposed design, so we would want to exclude anything that would cross a dollar mark as far as the total cost goes.

So I thought of an innovative way of replacing an MOV with an ordinary, cheap alternative.

What is the function of an MOV

It's to sink the initial burst of high voltage/current to ground such that it is ground before reaching the LED in this case.

Wouldn't a high voltage capacitor do the same function if connected across the LED itself. Yes it would surely operate the same way as an MOV.

The figure shows the insertion of another high voltage capacitor directly across the LED,  which sucks the instantaneous influx of voltage surge during power switch ON, it does this while charging up and thus sinks almost the entire initial voltage in rush making all the doubts associated with a capacitive type of power supply distinctly clear.

The end result as shown in the figure is a clean, safe, simple and a low cost 1 watt LED driver circuit, which can be built right at home by any eletronic hobbyist and used for personal pleasures and utility.


 Circuit Diagram

In the above shown simple 1 watt led driver circuit, the two 4.7uF/250 capacitors along with the 10 ohm resistors form a kind of "speed breaker" in the circuit, this approach helps to arrest the initial switch ON surge inrush which in turn helps to safeguard the LED from getting damaged.

This feature can be replaced with an NTC which are popular for their surge suppressing features.

This enhanced way of tackling the initial surge inrush problem could be by connecting an NTC thermistor in series with the circuit or the load.

Please check out the following link for knowing how to incorporate an NTC thermister in the proposed 1 watt LED driver circuit

The above circuit can be modified in the following manner, however the light may be a little compromised.

A good way of tackling the initial surge inrush problem is by connecting an NTC thermistor in series with the circuit or the load.

Please check out the following link for knowing how to incorporate an NTC thermister in the proposed 1 watt LED driver circuit


3) A Stabilized 1 watt LED Driver using Capacitive Power Supply

Stabilized 1 watt LED Driver using Capacitive Power Supply

As can be seen, 6nos of 1N4007 diodes are used across the output, in their forward biased mode. Since each diode would produce a drop of 0.6V across itself, 6 diodes would create a total drop of 3.6V, which is just the right amount of voltage for the LED.

This also means that the diodes would shunt the rest of the power from the source tp ground, and thus keep the supply for the LED perfectly stabilized and safe.

A 1 watt LED connected with the above circuit would be able to produce around 60 Lumens of light intensity, equivalent to a 5 watt incandescent lamp.

 Prototype Images

The above circuit can be modified in the following manner, however the light may be a little compromised.

4) 1 Watt LED Driver Circuit Using a 6V Battery

As can be seen in the fourth diagram, the concept hardly utilizes any circuit or rather does not incorporate any hi-end active component for the required implementation of driving a 1 watt LED.

The only active devices that's been employed in the proposed simplest 1 watt LED driver circuit are a few diodes and a mechanical switch.

The initial 6 volts from a charged battery is dropped to the required 3.5 volts limit by keeping all the diodes in series or in the path of the LED supply voltage.

Since each diode drops 0.6 volts across it, all four together allow only 3.5 volts to reach the LED, lighting it safely, yet brightly.

As the illumination of the LED drops, each diode is bypassed subsequently using the switch, to restore the brightness of the LED.

The use of the diodes for dropping the voltage level across the LEDs makes sure that the procedure does not dissipate any heat and therefore becomes very efficient in comparison to a resistor, which would have otherwise dissipated a lot of heat in the process.

5) Illuminate 1 Watt LED with a 1.5V AAA Cell

In the 5th design let's learn how to illuminate a 1 watt LED using a 1.5 AAA cell for a reasonable amount of time.The circuit is obviously based on boost driver technology, other wise driving such a huge load w such minimal source is beyond imagination.

A 1 watt LED is relatively huge when compared to a 1.5 V AAA cell source.

A 1 watt LED needs minimum 3 volts supply which is double the above cell rating.

Secondly a 1 watt LED would require anywhere between 20 to 350 mA of current for operating, 100 mA being a respectable current for driving these light machines.

Therefore using a AAA penlight cell for the above operation looks very remote and out of question.

However the discussed circuit here proves all of us wrong and successfully drives a 1 watt LED without much complications.

THANKS TO ZETEX, for providing us with this wonderful little IC ZXSC310, which requires just a few ordinary passive components for making this feat possible.

Circuit Operation

The diagram shows a rather simple configuration, which is basically a boost converter set up.

The input DC of 1.5 volts is processed by the IC to generate a high frequency output.

The frequency is switched by the transistor and the schottky diode via the inductor.

The rapid switching of the inductor provides the required boost in the voltage which becomes just appropriate for driving the connected 1 watt LED.

Here, during the completion of each frequency, the equivalent stored energy inside the inductor is pumped back into the LED generating the required voltage boost, which keeps the LED illuminated for long hours even with a source that's as small as a 1.5 volt cell.


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!

98 thoughts on “5 Easy 1 Watt LED Driver Circuits”

  1. Howdy, Friend! Interested to Learn Circuit Designing? Let's Start Discussing below!
  2. Hi Swagatam, i tried the basic transformerless circuit from u r previous posts and ive used single 1 watt led but resistor started heating up. I am using 474k/400v cap and single led (1 Watt) . since there r many ckts in ur site which uses 1uF cap suggest me a ckt suitable for me….

  3. Sir, could I put NTC in place of so many diodes in the under mentioned circuit, then will it become surge proof ? could I put about 15 no. of 1 watt LED for that ? Is there any alteration needed ?


    • Raja, yes that's possible but NTC will need to be placed in series with the supply, not at the points where diodes are connected.

      it will prevent surge but it will not stabilize the voltage, and it is recommended only for initial switch ON current control not for round the clock control

      15 no LED can be used, but should be in series

    • Yes, make sure all the parts along with the 1N4007 diodes are original, and of good quality.

      use a 12V / 1 watt zener across the output +/- lines, this will prevent the capacitor from getting damaged.

      remember this circuit is for 1 watt LED, NOT for 20mA LED, if you want to use 20mA LED then replace the 105/400V capacitor with a 0.22uF/400V capacitor.

      please don't do anything without understanding

  4. Hi sir, I made circuit and actually was working perfectly but after 2 minutes the third capacitor 100uf 63v got burst, I was using only one red colour led (normal) everything else is same.

  5. hello swagatam sir,
    in the first circuit ,instead of 4.7uf,250v can i use 10 uf,250v.
    If i make first circuit as it is ,then also NTC is necessary?
    aabhishek sharma

  6. Blog has been removed

    Sorry, the blog at homemadecircuitsandschematics.blogspot.com has been removed. This address is not available for new blogs.

  7. Hi Swagatam,
    I have been following your blog for quite some time.Its a very good blog and I have made many circuits by following your circuits. I wanted to make led street lights but the frames i have are the old types you know those 40 watts one. So can you tell me how to make them like the circuit and what type of led's can be used to have bright white light.

  8. sir I want to build a circuit without transformerless power supply for eight led 4-4 series and two series are parallel,
    but I can't build this circuit. Please help me

  9. hi Mr Swagatam, I would like to make a single on /off button switch circuit that controls 2 different paths to switch 2 different appliances at each on/off button, means first press ON it switches on a lightbulb A, press button again it switches OFF light A, press same button again, it will switch lightbulb B, press same button it turns off, press again it comes back to light A,and so on..

  10. Luego de casi un lustro llega a Sur América problemas para resolver tecnolócamente que ud mi estimado amigo ha resuelto y compartido… gracias… hacía hace un tiempo este circuito para leds de 60mW y me preguntaba si funcionaría con chups de 1w. Saludos y gracias.

    After almost five years come to South America to solve problems you my dear friend and shared resolved … thanks … some time ago this circuit 60mW LEDs and wondered if it would work with chups 1w. Greetings and thanks.

  11. Hi friend,
    I liked 2nd diagram, but I don't have 10uf 250v capacitor at the moment, currently I have:
    10uf in 16v, 25v, 50v, 63v.
    so what capacitor voltage I can use instead of 10uf 250v??? please suggest me.

  12. Sir!
    Can this be modify to detect overvoltage, a spike or a transient
    in the mains? Light up the led, and way not log it with an ARDUINO 😉
    Tank's, Joe.

    • Baron, the over voltage can be simply stabilized by putting a zener diode across the LED terminals, and the spike or transient can be controlled by inserting an NTC thermistor alone or in conjunction with an MOV 😉

  13. Hi friend,
    How are you? hope u doing gr8, I am again in little confucsed with led current value, i mean i went to market few days ago to buy 50nos 1w led, but in one shop i got only 20nos and another shop i got 30, so i got total 50nos. Ok after taht i came to home and connect led's to desire voltage (output voltage of battery is 3.2v) the 20nos of led (from 1st shop) brightness is ok, but another 30nos led (from 2nd shop) brightness is different, my question is how to know led current value, i mean 350ma or 300ma? is there any calulation method or any way to check the led current????
    Thank you….

    • Hi friend, I don't think there's any testing equipment or method which will identify the wattage of an unknown LED??

      but in your case it's just because of difference in quality or color spec….both could be 1 watt/350mA but due to different brand, the illumination could be slightly different.

  14. dear Swagatham, in reference to the simple single diode schematic diagram : can I replace the 1megaohm resistor in parallel to the 105uf 400v ac capacitor with a neon bulb instead? the 1 megaohm resistor is a simple discharge mechanism to prevent the cap from keeping its current in it and causing a shock when touched accidentally etc whilst being removed from the ac outlet right?

    • dear fidel,

      you can use a neon bulb in series with the 1M resistor…..but you cannot replace it

      that's right, it's for discharging the dangerous mains potential when the circuit is unplugged

  15. Dear sir,
    I want to attach it a single 5 mm led to project its beam on the wall clock.
    So how can be modified this circuit for a single 5mm led? (enough brightness which shouldn't harm led's durability)
    Thank you so much sir.

    • use a 0.33uF/400V capacitor in place of the shown 105/400V cap, you can try a 0.22uF/400 first if it does not give sufficient light then go for the 0.33uF/400V option

  16. Dear sir,
    this is Shrinivas from Amravati.
    How can be modified this circuit to draw 20mA (for single 5mm LED)? Coz I've tried single 5mm for this circuit bt it lits very brightly which is resulting high temp & no durability. So please suggest exact value (for R?)
    Thank you so much sir.

  17. series connection does not call for current multiplication, rather it involves voltage multiplication….so for 50 LEDs in series current requirement will be 100mA….but voltage requirement could be approximately 50 x 3.3 = 165V

  18. IN 4007 diode is rated for 1000v – 1A. connecting 50 x1w leds would put 5000mA (100mA per 1W led) through the DIODE Bridge.. Pl explain how can it work?

  19. Hello Swagatam,

    i have followed ur ckt . i want to connect the 18 LED having voltage 3.2V Current 150mA . i have used the 105J 400V capacitor . on AC side the current consumption is 70mA while on DC side at led it is 55mA only . I want to insincere the DC current at led side up to 130mA and decrease the AC current up to 30mA.

    Kindly suggest mi how to do that

  20. Hi Swagatam, i like your blog. i have question related changing "2pcs of 4,7uf/250v and 2 pcs of 10 ohm/1watt with 1 pcs of NTC. what value of NTC of it? is it 20 ohm?

  21. hello,
    Can you suggest a circuit to reduce the flickering of LED which is powered by energy generated from a small turbine rotated by water.approx voltage across LED is 1.6v

  22. hai sir,
    i am aravind
    while i am surfing through internet i found that 1uf cap will provide 40ma.
    then how it glows 1 watt led which requires 300ma.
    does 40ma amp is enough?
    please explain.

    • Hi Aravind, 1uF will produce 70mA not 40mA, but anyway the LEDs will not get 300mA from it and will light up with 70mA brightness only.

  23. PLEASE help me i need 12-17 voltage circuit and minimum 0.5 ampere current and i only want to use maximum of 2 reistance and two capacitor and one bridge rectifire like in the circuit i mentioned in link.I just want to know the value of resistance and capacitance for my purpose

    • Sorry that's not possible, you will have to include a transistor stage also for reliability and safety because at 0.5amps the initial surge will be too high which could damage the load instantly.

    • Hi Naresh, It would settle down to the 100uF capacitor voltage rating without load. and when a load is connected such as an LED it would further come down to 3.3V

  24. Hi, Can you guide me with making of LED Street light using 30 Nos. 1W SMD LEDs connected in 3 rows in parallel with 10 LED's in Series. I will use available ready-made good LED Driver (pls give spec of Driver required). Thanx

  25. Hello I like your post very much keep it up!!!
    Can I connect about 50 ,5mm leds to this circuit without big 1W leds??

  26. Hello Sir,

    I have seen your posting of 1watt led drive from mains supply its good i have tried but,
    my led has blown out and i have checked the out put is showing 320v Dc..
    I have used the the below parts..
    1) 1N4007
    2) Resistor 1mego ohm 1/4watts
    3) Resistor 56ohms 1watt..
    4) capacitor 105/400v polyster type.
    5) Capacitor 104/250v polyster type.
    6) LED 1watt white.
    I have connected as per the draw shown above kinldy le me know where im doing the mistake..
    mains voltage i have given 240volts to the above circuit..
    Kindly help me sir…

  27. how to lighten up 20 LED of one watt each connected in parallel , n how many voltage require i have a 35voltage DC battery and how to control upcoming voltage from battery to glow much brighter

    • with 35V you get an opportunity to connect 10 LEDs in series with a single limiting resistor, so with 20 LEDs you can make two such strings and connect them in parallel.

      The resistor value will be 6 Ohm 1 watt for each string.

      The above set up will produce the most optimal response from the LEDs

  28. Dear Muhammad,

    You will have to measure the volts across the leads of the LED, and measure current in series with the LED, then multiply the results to get the wattage.

  29. Hi sir I'm planing to connect 40 1 watt led's in series so i want to add an fan speed controller for dimming. I'm interested in electronic but i don have much knowledge in electronic plese help me can u send me the pic of ready circuit for reference wajedpasha58@gmail I'm waiting for Ur reply

  30. Hi, What is your driver voltage?

    You will need to put appropriately calculated resistors with each ED, only then all will light up with uniform brightness.

  31. Can you please provide me any link, or provide me some hint to understand how did you arrive at the input side capacitor of 1uF/400V? I mean how does this value of capacitor restrict or limit the current that is being used by power-led? Also how are we restricting the voltage supplied to the led to 3.4V. I know that even if we provide 5V to the led the forward drop will always be 3.4V; but still if we provide a higher voltage maybe something like 200Vdc then I believe the led will burn out. Then how do we limit the voltage supplied to the led?

    • The current is important here which we want to limit by putting a resistance in series with the mains, the capacitor acts like a resistance here which is calculated by calculating its reactance, you can Google a little to find the formula for reactance, this will be in Ohms, next you can employ Ohms law to calculate the current that can be limited through this reactance or resistance.

    • The voltage gets automatically restricted to load voltage only in case the current is considerably lower than the maximum spec of the load (LED here), since a 1uF/400V can allow a max of 70mA which is far less than the 1watt LEDs 350mA, the voltage settles down to the LED FWD V level

  32. …i mean it won't drive with full illumination, anyway you can try connecting the LEDs in series with the above circuit and see the results.

  33. hi!
    when I made the above ckt the resistor 56 ohms just gets blows and if it doesn't, the LED lights up but with very low brightness

    • please make this circuit:


      Use 6 diodes and not 12, if you are connecting 1 LEd only

  34. Sir

    when i have made this circuit i got only 2.82 volt on each 1 Watt led.. so pls help me how to increase volt to 3.3V…
    I have used following items…
    1. 105K/400volt capacitor
    2. 150 or 570K resistance for cap
    3. 4 diode 4007
    4. 56 ohm resistance 2 watt
    5. 100V/100mf condenser
    6. 1watt 3LED in series

    • Hi Vivek,

      Increasing current won't be a good idea and is not recommended for such power supplies, instead you can use ordinary 5mm LEDs and connect 50 of them in series, it will produce much higher illumination than a three 1 watt LEDs.

  35. Dear Sir, i am no expert like you..

    i want to try build a led driver.

    the DC output should be

    14 Ampere (60 * 700mA) , 168 volt (2,8 * 60) , 60 Watt (60 pc * 1 W)

    since i want use 1 W led, DC2.3-2.8V 700mA each (read it on the spec of the bulb)..

    i want to use 60 piece bulb of 1w power led.

    is the DC out that i calculate is right or wrong ?

    • Dear Andre,

      You can use the circuit which is given in the above article, by connecting all the LEds in series to the output. Be sure to connect a thermistor in series with the input of the above transformerless power supply and increase the input capacitor value to 5uF/400V non-polar

      Your current calculation needs correction…..when LEDs are connected in series the current gets shared, meaning in your case the current would be just 700mA…..
      By the way 1 watt LEDs are rated at 350mA not 700mA, I am doubtful about your specs.

  36. Hello Swagatam!
    Thank you for all of your time answering everyone's questions. I would like to use your circuit design in a middle school project to create LED light fixtures housed in home cut and planed cherry wood housings. I am wondering which of your two posted designs you would recommend for this project, and how many 1 watt LED's you think would be appropriate for a 3 foot long bar type fixture to give an impression of consistent lighting when used as uplighting mounted above eye level on a wall (I am imaging a simple V design for the housing).

    Thank You!

    • Hello Shaun,

      34nos 1 watt LEDs would be enough within a 3ft span. Remember that you will need a heatsink back PCB for mounting the LEds and an additional thick aluminum heatsink attached behind the PCB for optimum cooling.

      Along with this you will have to incorporate a current limiter circuit with each LED module, and the the whole thing will need to be powered through a 2amp 12V smps.

      For wiring details and calculations you may refer to the following post:


  37. CFL bubs are very complicated to build because they involve inductors which are too critical…so i am sorry, no ideas.

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