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Converting a Dead CFL into an LED Tubelight

Last Updated on by 48 Comments

You might have already read about this interesting idea in many different sites. It's about converting a dead CFL into a sleek LED tube light circuit. In this post we learn the procedures with more details.

How many times did you throw away a dead or over used faulty CFL unit into the dust bin? Well, we do this quite often whenever we find one of our home CFL lamps no longer illuminating or illuminating dimly.

You would be surprised to know that the circuit inside the lamp in fact never blows of or becomes weak. It's the tube portion which gets blackened, and unresponsive. It means the circuit of most of the discarded CFL units never goes faulty, and can be recycled through some other means.

For a layman this might look pretty tough....but actually it's quite easy. The tube portion of the CFL may be simply replaced with LEDs, and reused for getting the same illumination that your previous CFL used to give... well almost the same.

Let's learn the procedures.

How to Convert CFL into LED Bulb

Find a dead CFL unit, and very carefully open up the lid which holds the tube from the lower cup type enclosure.

You must do this very carefully using a screwdriver equipment, making sure you don't damage the internal circuit while doing this.



If  you find it difficult to insert the screwdriver end across the joint opening, use a fine hacksaw to make a small section of the opening wider by sawing it some. Now you can force open the lid by using the screwdriver.

This will immediately expose the internal circuit and the connections.

You will find the tube ends terminating with a pair of wires and connecting with the circuit board at four points arranged in a row through fine wire links. Cut these connections with a sniper so that the tube portion gets separated from the circuit board.

Join the above terminals from the ends so that only two terminals end up as the output.

Next using 4 nos 1N4007 diodes build a bridge rectifier, and connect it to the above terminals as shown in the diagram.

Now through a suitable holder and plug device connect the above system to mains and check the voltage a the output of the above connected rectifier.

It should be around 100 to 150 volts DC.

You have just transformed a dead CFL into a small transformerless power supply ideally suitable for illuminating LEDs (white).

Now comes the LED assembly part which may be constructed in the following manner:

To figure out the number of LEDs that would fit inside the output voltage of the above unit, we need to divide the measured voltage with 3.3V. Suppose the measured voltage was 120V, dividing this by 3.3 would give around 36 (numbers).

Use the derived number of LEDs and connect all of them in series with a 5 Ohm, 1/4 watt series resistor.

Done! Now simply connect the LED assembly end terminals with the bridge output of the modified CFL power supply.

You can test the system  by providing mains supply to it....the LEDs should illuminate with dazzling light.

Now fix the assembly appropriately so that the CFL circuit gets inside its original holder while the LEDs may be integrated to the holder over a suitable rectangle type of box, or inside any other decorative cabinet as per user preference.

WARNING: THE IDEA IS BASED ON A SIMILAR CIRCUIT WHICH WAS PUBLISHED IN A DIFFERENT WEBSITE, IT HAS NOT BEEN VERIFIED BY THE AUTHOR.

THE CIRCUIT IS NOT ISOLATED FROM MAINS, AND THEREFORE IS EXTREMELY DANGEROUS IN UNCOVERED, POWERED POSITION.

 

 

 






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Comments

  1. hi all,
    in this circuit we are shorting two points which, originally were having a filament of lamp in between them, means some resistance should be there , but if you just short them, how will it work?

    Reply

    • इस cfl के सर्किट में आउटपुट 40v,ac आता हे diode 4007 ractifive करने पर,40 v तक ही led की series use कर सकते हे, स्वागतम सर मैने चेक किया है,led heat होती है,hestsink लगने पर भी

      Reply

  4. What's the output of a 5 watt CFL,,and anyway of converting the output from a flyback transformer driven by 5 watt CFL,,,soo do I connect 10;in4007 diodes in series and make a rectifier with 10kv standard,,,,and finally HVDC into normal 300 v using bunch of resistor and regulator and inductors
    Is there any lol wat I stayed,,,or it works 100% sure sir
    Waiting for ur reply
    👏👏😋👍🙏😘😍

    Reply

    • the output will be 5 watts with voltage level in many hundreds of volts, because CFL tube requires high voltage to ignite. sorry can't answer the second question because I am not sure about it???may be this diagram will give you some hint 🙏😘😍

      https://homemade-circuits.com/2014/03/mosquito-swatter-bat-circuit.html

      Reply

  5. SIR , by the dead CFL can i use that as an dc power supply to my circuit projects. if yes how much DC volt can i get from 15w cfl . and how can i test how much volt that i can get from different cfl's of different watt'age thank you

    Reply

    • Manjunath, that's not possible, because CFL drivers are designed to generate high voltage and high frequency at their outputs, not suitable for DC power supply application.

      Reply

  8. I have 20watt CFL with 400volt 8.2 micro farads capacitor.please tell me how to modify the circuit to make high voltage bug zapper. I have 4 capacitors with 400volt 2.8micro farads capacitance please help me out.

    Reply

  10. Hello sir
    I m manoj . I m working on a cfl pcb.its working fi9 but I want to add a mov for better protection. Plz suggest me a move for 15 w cfl pcb.i m using 13003 transistor.plz help me with the value of mov.
    Thanks

    Reply

    • Hello Manoj,

      you may use a 300V/10amp peak MoV as shown in the following image:

      www.setfuse.com/shaiweite/assets/js/upfiles/images/products/home_product10.jpg

      Reply

  11. If I have an input voltage of 240volts on the CFL board thus the output circuit remains the same for the LED's

    Reply

  12. hey swagatam i made this circuit my led glows for 5 minutes than without harming any led or other component just stop glowing and i figured it out in both terminals there is power showing how can i fix that problem please do reply fast

    Reply

    • Why you just put a circuit design here without verifying it by yourself??
      Is it very difficult to experiment with this small type of circuit by an 'Expert' like you?
      We expect 'concrete' advices from you and not suppositions….!
      :-((

      Reply

  18. shorted 2 wires and connected to the mains as suggested, there was a spark ,noise and burning smell.I wanted to check the voltage between two points before trying out the led circuit

    Reply

    • If you have another spare CFL, try once again, but this time do not short the outputs, connect the bridge rectifier on the pins which are linked with the small ferrite transformer.

      If it still blows of would mean that the above concept is rubbish.

      Reply

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