A Simple, Low Voltage Inverter for Fluorescent Lamps Up to 15 Watt


Introduction: A Simple, Low Voltage Inverter for Fluorescent Lamps Up to 15 Watt

About: I am a high school student in Cairns, Queensland. Most of the time I am either at school, sleeping, doing stuff on my computer, making circuits of some kind or messing with 240v

Thankyou to Burak Incepinar for letting me document his design. This is his website if you want to check out more awesome designs.

This Instructable will help you run any fluorescent light off low voltages, It has been tested to run Compact Fluorescent Lights and Fluorescent tubes up to 15 watt.

Step 1: Parts

Things you will need:
  • 25mm x 20mm x 5mm ferrite core.
  • AWG28 (~0.3mm) Magnet wire.
  • AWG32 (0.2mm) Magnet wire.
  • 2x 22nF unpolarised capacitor, I used ones out of a camera flash.
  • 22 ohm resistor (red red black gold) OR a variable resistor.
  • 470 ohm resistor (yellow violet brown gold) OR a variable resistor.
  • A BD243C or similar NPN transistor.
  • A fluorescent light to drive.
  • A battery or power supply of your choice.

Step 2: Dismantling the Ferrite-cored Transformer

Try to pull the two "E" cores apart. Usually they have a little glue between them which makes it extremely hard to dismantle without breaking the ferrite core. Mine broke at the ends which still gave me space to wind/unwind it.

If your ferrite core breaks at the end, You can usually glue them back together with little performance degradation.

Step 3: Wind the Transformer

The hardest step if you can't count to 250...

Use AWG28 (~0.3mm) wire to form primary and feedback windings and AWG32 (0.2mm) wire to form secondary. Make out a smooth winding for maximum performance and easy fitting. Place primary and feedback windings on opposite sides of the frame. Primary winding will run over on feedback in this case but it is not so important. It also isn't important in which direction the windings are made, you just have to change two wires' places to make circuit work, But for a problem less first run and make the transformer to fit on the PCB right, follow these instructions:

Start by numbering the four slots on your transformer 1, 2, 3 and 4. Start by winding the feedback. Put wire at slot two (leaving a bit of wire free to connect to the pins easily) and wind 18 cycles clockwise, When done put the wire in slot three. Start on slot 4 for primary, wind 25-30 cycles clockwise and end in slot 1.

Wind secondary with AWG32 wire and wind 250 cycles turns from the other end of the transformer

If you make a mistake at this point or just confused, it does not matter at all. Allow wires came out 2cm or more long from the frame, then you will be able to swap feedback (or primary) connections in case of wrong phase polarity.

Step 4: Put the Transformer Back Together

Put your transformer back together, Making sure that if you broke the core that it goes back together the right way.

There should be thin spacers made out of adhesive tapes, between the contact points of core parts. If you got your ferrite core with this spacers on it, do not remove them. If there isn't any spacers, you can use very thin adhesive tape to make them. If you don't use any, performance of the transformer will be degraded. You should manually move two core parts relative to each other in order to find the best operating point which can be determined from the brightness of the lamp.

Step 5: Make the Driver Circuit

WARNING, Only use the driver circuit when there is a fluorescent tube connected to the output or you can damage your transistor.

Using the schematic, Put together the driver circuit, You should use a breadboard at first to make sure everything works because it is very hard to trouble shoot a part on a PCB.

Once tested and working, you can make a PCB for it using the included PCB layout, Change it to match your transformer.

Step 6: Is Your Circuit Not Working?

If it isn't try:

  • Reversing the feedback wires
  • Check all your connections
  • Does your transistor work, If not get a new one.
  • Has your circuit got power, If not, FIX IT!

Enjoy the pics of the 12 volt driven fluorescent lights.

F8T5 tubes can be easily light up with the inverter. Just take this advice: as the tubes get old, they draw more current from the inverter. So always use a tube that lights up well and consumes less current.

Remember to comment and rate!



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1)what is the operating frequency of this circuit.

2)does frequency varies no load to full load.how much...?

would this work for EL wire? (have been looking every ware for a DIY inverter cant seem to fined one at all.)

this is great! but, is the secondary windings clockwise too?

nice one .but i want ask dose the transistor need heat sink?

Wow, what a great circuit. It was my first time winding a transformer and it worked on my first attempt. I first used 2SD882, cfl blinked for a bit but didn't ignited. Then i used D313 and it worked, the brightness is low compared to the pictures you have here but i believe its 70% bright. I tried adjusting the ferrite core but it is already on its peak, any more further adjustments to it will only decreasing the brightness. I made the exact number of turns as exactly you described. I think the only thing i missed is wire gauge. I got the secondary winding wire by dismantling the transformer itself. I believe it is awg32, but the problem was awg28, i didn't had that, tried asking it on the market and they refused to give it to me. Then i desmented another transformer from a dead cfl. It could be either awg31 or 30 or 29 but its not 28 that's for sure. Can you also tell me what should be the margin of awg in primary and secondary windings. I mean if i use awg36 for the secondary, then what should be the awg of primary and feedback?

Also do u think the low brightness is due to the lack of cycles? i made exact 250 turns using awg32 wire.

this is the first circuit that has had me stumped, tesla coils no worries but a simple inverter for the light i use to make it, :( , anyway, wont work for me, tried swapping feed back line primary lines, different transistors, resistors, caps, batteries and power box, ive even rewound the transformer 3 times, still wont go

2014-06-05 12.09.50.jpg

What is the value of the transformer ? reply fast please

Great circuit small, compact and easy to build. Thanks for this instructable.

i dont get it why use ferrite?transformers can also use iron right?my transformers are all iron frame...is ferrite better than iron?

10 replies
  • Iron core transformers are design to operate efficiently on low frequencies, (20Hz to 1000Hz).
  • Ferrite transformers are design to operate efficiently on high frequencies, (1KHz to 100KHz)
You can get ferrite transformers from newer electronic devices or switch mode power supplies.

DARN MAN!! YOU ARE SMART FOR A 15 YEAR OLD !!! Are you related to Albert Einstein?or Thomas Edison or are you an Alien from a planet millions of light years away? Your instructables are my favourite though (whoever you are)...My favourite is the Smallest Electronic Shocker,i did it and it works (i connected 2 thin wires and put em behind my door-knob and my sister got shocked!LOL!)...I want to take out flyback transformers and microwave guts but my parents say that its too dangerous.I cant wait to be 18 and get out man...

No, I am just a normal kid who has Asperger syndrome.

LOL, shocking other people can be fun... And my parents were like yours when I first got into high voltage, they got freaked out when I built a 330v power supply and they told me I am not to experiment stuff with voltage over 9v. But I disobeyed them and continued messing with high voltage. After many months, they now feel safe me dealing with high voltage, but still, I am not allowed to exceed 100Kv... Right now, the highest voltages I can go up to is 60Kv from my marx generator.

i'm just like you.

Ya know. I think I have have asperger syndrome to but for all I know, I just have ADD.

Hey =)

I thought I was the only 15 year old on here with Aspergers. Just built a variable DC power supply and am now looking for a basic inverter schematic to modify to hopefully power a CFL which in turn will drive a fly back. I did have my suspicions of other 15 year olds who actually knew what they were talking about with electronics but I thought it rude to ask if they also had AS. Thank you, for making me feel less alone =)

actualy, i thought i was the only one on here with aspergers lol. although im not a kid (im 23) its realy cool to find 2 other people with the same battle and with the rarety of aspergers it realy dose make you feel less alone.

There are more of us than you think. Why not check out the ASD forums? http://www.asd-forum.org.uk/
Welcome to the team xD

awesome.....wish i had your parents instead of mines,they are always telling me "dont blow up the house" or "dont burn the house down" and other parenty stuff...☺

Don't get all jealous and that, my parents are like yours too... :-(

They have so many harsh rules on me, I will tell you some...
  • I am NOT allowed do do electronic experiments in my house.
  • I am threatened to be banned from my workshop if I have a source of flame or hazardous chemical or experimenting with dangerously high voltage (100Kv+) in my workshop.
I am also limited how much power I can have going to my workshop (240v at 5A) which prevents me doing high power projects... :-(