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Forum Index : Electronics : DIY 12V CFL lamp
| Author | Message | ||||
| Dinges Senior Member  Joined: 04/01/2008 Location: AlbaniaPosts: 510 |
After I had to replace two 220V CFLs in the living room (installed on 13/1/2005; cost 3E/pce at the Aldi; didn't last more than 3.5 years. Grr...) I was left with 2 defect CFLs on the workbench. Gave it a quick go to try to repair them but alas. Anyway... On that same bench was laying an old CCFL (cold-cathode FL) tube with inverter board, that was once taken out of an old broken flatbed-scanner. "That board is tiny", Dinges thought, "it *may* just fit inside the base of that CFL..." 
After some judicious use of a file to round off the edges of the PCB it fitted. Soldered the 220V wires to the 12V inputs of the board, and soldered some extra red wires on the board to connect to the CFL bulb. Applied copious amounts of hotglue to make sure it all stayed in its place... 
Closed it up again and gave it a test. Yep, works fine. Draws 0.31 A out of the 12V battery so about 3.5 W input power (it was originally a 7W CFL lamp). Plenty of light. Considering the price of 12V CFLs over here (they easily fetch 16-22 Euro per piece) not too bad for half an hour of work. It may not last as much as a real 12V CFL, but normally this particular one would have ended up in the trashbin. Now I can squeeze at least a few more hours of life out of it at 12V. Still have to mark the bulb clearly as a 12V one. Wouldn't want to accidentally plug it into mains...  |
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oztules Guru  Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Neat project. I still think you should have fixed them first ... then done the conversion. 
You know I like to see you suffer.
.........oztules Village idiot...or... just another hack out of his depth |
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sPuDd Senior Member Joined: 10/07/2007 Location: AustraliaPosts: 251 |
I had a CFL fail a while back. Turned out to be a 680K resistor had gone to about 800K. Seemed like a long shot but replacing it fixed it. I think it was a startup resistor similar to the way most SMPSU's get their initial startup voltage. I put it back into use and its still going. sPuDd.. It should work ...in theory |
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indexterslabor Newbie  Joined: 03/08/2008 Location: Posts: 15 |
i think thats awesome, but what do u think caused the dead of the original board?? |
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| Dinges Senior Member Joined: 04/01/2008 Location: AlbaniaPosts: 510 |
Oztules, you know, I had *two* defect CFLs. One to modify, but still have one left to repair. If I had had only one I would have probably done what you suggested... repair... then convert to 12V... For me it's not suffering, it's fun and games... Maybe I need professional help ?
Then again, seeing I'm not the only one who tries to repair a 3E CFL (thanks Spudd for the mental support ), why bother with the quacks...
I tested some components on the board, the electrolytic cap (first suspect) and semiconductors. None were obviously bad. Checked for bad solder joints and all were fine. By that time I was already planning to convert it to 12V so didn't pursue the repair much further. Interesting observation on the resistor that shifted in value. Such a small shift causing it to not work. Hm. Dexter, no idea as to the cause of the defect. Your guess is as good as mine. Could be anything from ageing components going bad or shifting in value over time, bad solder joints, power spikes or brown-outs, or just plain bad karma. Edit: site with lots of schematics of various CFLs and repair info: http://www.pavouk.org/hw/lamp/en_index.html |
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| sPuDd Senior Member Joined: 10/07/2007 Location: AustraliaPosts: 251 |
Had a look at the site you linked Dinges. Dang, I was right, the resistor was a startup unit. I did the old blame the caps & silicon, but it turned out to be a simple resistor drift. sPuDd.. It should work ...in theory |
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