Picture of Take apart a Compact Fluorescent Bulb
Compact Fluorescent Light Bulbs (CFLs) are increasingly popular as a way to save some energy. Eventually, they do burn out. Some seem to burn out annoyingly quickly :-( Even if not burnt out, CFL bulbs have become very cheap, especially if you live in an area where they get subsidized by your local electrical utility.

Are there any hobbyist usable electronics parts inside a CFL? How do they work, anyway? And when they burn out, why have they burnt out?

Let's take some apart and see!

(This Photo by PiccoloNamek from Wikipedia. Hopefully this is sufficient to meet the requirements of the license; I didn't have my lawyer review the Gnu Free Documentation License)

Step 1: Take it Apart 1: cut a pry-slot

Picture of Take it Apart 1: cut a pry-slot
Most of the CFLs I've seen have a seam where they can be pried apart without too much difficulty. Sometimes the seam is glued or "welded" together, other times it's just where two pieces have been "press fit" together.

Unfortunately, even if only press-fit, the two pieces are usually too securely attached to just pry them apart with your hands, if only because one of the halves has only the glass tube to get a grip on. Sometimes the joining seam is loose and/or large enough to fit in a flat-blade screwdriver, but it is easiest (assuming you don't want to re-use the bulb casing) to cut a shallow slot at the seam with a hacksaw. Just hold the housing securely (in a small vise as pictured, or not), and saw a slot just barely through the casing - about 4mm.


Try REALLY hard not to break the glass fluorescent tube. Aside from sharp edges, fluorescent lights contain phosphors of unknown and possibly dangerous composition, and a small amount of mercury that you'd rather not have released in your home or workshop.
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richardebueramosii made it!26 days ago
Dismantling a CFL bulb is like a trip from the electronic hardware. There's a lot of things you could salvage. Thanks for this! I really needed a ferrite toroid for a joulr thief and now I have one, thanks to this guide.
laci376 years ago
Mercury is very toxic, but its not so dangerous in small amounts like this if there is no strong airflow it stays near the ground.
junits15 laci376 years ago
u do realize that the amount of murcury in one of these is not nearly enough to kill you, it wont even make u feel sick
Peeet junits156 years ago
Not the point--heavy metal contamination is cumulative. It accumulates in the body. If you eat shark too many times a week it can be hazardous for the same reason--them being near the top of the food chain we get the end results of their build-up. There are a lot of hazardous inputs that won't make you feel sick immediately.
shomas Peeet4 months ago

Your body takes in some and eliminates some so it is not cumulative. If it were cumulative, you could have only so much shark over your entire lifetime versus how much shark you can safely eat in a week. For health concerns, it is about how much you take in and how fast you eliminate it that results in either relatively safe or relatively toxic levels in your body.

junits15 Peeet6 years ago
oh i didn't realize it was accumulitive
shomas junits154 months ago

The accumulative argument is nonfactual and espoused by persons who do not know better. My comment above to Peeet explains why.

 are you super sure? I just broke one and I'm freaking out

read below
dawp laci376 years ago
I think some concern borders on hysteria and lack of common sense. If i should accidentally drop a fever thermometer (there i really dated myself) i don't think i would call the men in the space suits. The XEROX company tried to make a dental imaging machine based on xerographic principals. They found out that the residual mercury in the dentist's carpets "poisoned" the drum. The project was eventually dropped. The same also is said to hold true if somebody breaks a fluorescent tube in a room where a XEROX machine is installed. For us hoomons It is the mercury compounds that are dangerous and that is what accumulates in fish organs, etc. Mercuric chloride is a deadly poison. Years ago our chemistry teachers in high school would pass liquid mercury around the classroom. Now they fire a teacher if he even has a vial of the stuff.
webgiant dawp1 year ago
Concern about mercury in CFLs does border on hysteria. You could spend months shattering 100,000 CFLs in one spot on your carpet, and once you had finished shattering the 100,000th CFL, you would finally have some cause for worry about mercury poisoning as an adult.

The bigger problem with CFLs, where the hysteria is justified, is pets, children, and the elderly. Mercury affects these groups much more than adults, and children and pets might lick the carpet. So if you have a household with no pets or children, then there's not much to worry about with breaking a CFL.

For those who worry about breaking them anyway, here;s a simple comment: think about the number of times you have ever broken a standard incandescent light bulb. Now divide that number by 10. Since CFLs generally last ten times longer than incandescents, this is the number of times you will break a CFL. Chances are this new number will be less than zero.
Yes, I remember being allowed to roll it around on our hands - that's really going back some!! I'm almost 60 - phew!!
True. Also it's not that much mercury. There are higher level of mercury it some fish.
pavelanni made it!6 months ago
I used a small hand saw before prying the bulb with a screw driver. The rest was easy.
Akshat Ag7 months ago
This is very usefull for my project
dillonxti1 year ago
to get mine apart I just whack the seam with a small hammer
james346022 years ago
I use this circuit for my flyback transformer driver
ilovegm3 years ago
Darn, my buddy gave me a blown out bulb he had, looked like a CFL, he thought it was one too.
When I opened it, all I got was a capacitor wired to a glass glow bulb starter.
Is the starter useful for anything other than lightbulbs?
Inducktion4 years ago
what can you do with the spaghetti stuff? :0
You eat it.

Just kidding ;D
Juxe Inducktion4 years ago
It's a flexible, heat-resistant insulator. It's convenient for big capacitors on small boards, to spread out the components.
So could you put a correctly sized capacitor in parallel with the flourescent tube and correct the terrible power factor in these?

no because fluorescent tubes have to have ac current, or the mercury gathers on one side.
ginbot863 years ago
When it comes to harvesting components from CFL bases, be sure to test those transistors. I cracked one open that burnt out in my bedroom and found that the E13003 power transistors were short circuited (reading 0 ohms on a multimeter) between the base and collector, base and emitter, or all three pins.

Higher-wattage bulbs have a (somewhat) greater chance that their transistors would have survived the lamp failing; I have some nice E13007 transistors, and some really nice MOSFETS of which I can't remember the part number right now.
westfw (author)  ginbot863 years ago
yes, you want to be careful harvesting components from bulbs that have actually burnt out in one way or another. The usual failure modes seem to take out several components. But these days the (subsidized) prices of CFLs are low enough that you can think seriously about harvesting brand new CFLs. (I think I've seen 4-packs for less than $5)
dan_moran6 years ago
I had my first CFL die (early in my opinion), so as I do with incandescents, I wiggled and tapped on it to make sure it was getting a good connection in the socket. It was screwed in tight but it will light up for a couple seconds when I tap on it. What do you think is going on inside this bulb and is it salvageable?
westfw (author)  dan_moran6 years ago
One of the failure modes I've seen is that a positive-temperature-coefficient (PTC) thermistor (think of it as an inrush limiter, I think) will apparently overheat (perhaps due to other problems?) and have one of it's leads unsolder itself from the component body...
The PTC is what Chrysler used to use in the 60's as an ignition ballast resistor. It's not so muchan inrush item as limiting current once a circuit is in operation. When it's cold ( startup, or colder conditions ) the resistance is low allowing more current. Once the circuit starts operating, current warms the PTC, raising the resistance and lowering the current. This allows the PTC to cool, lowering the resistance. At some point it will reach an equilibrium state based on demand (varying in a car, stable in a CFL) and ambient conditions.
What a great instructable! This is the best information on CFLs I found so far, most pages "informing" about them don't mention the electronics inside at all. The comments were great too. I have a couple CFL questions, maybe someone here knows: Taking macro photographs and using a 30 watt cfl as light source made me wonder; Is the light from a CFL more damaging to the eyes than a "normal" incandescent? And does it depend on the color of the light (2700k vs 6500k for instance). I had one quit on me with a popping sound, could that have been the electrolytic capacitor exploding? I have a little fan connected to my computers USB, I notice I can make it stop by pointing the CFL close to it. Magnetic field?
I never thought about the caps overheating and dying. I have several lights in my ceiling, and the CFL's only last a few months. Whereas the CFL's in normal lamps which get plenty of ventilation have never died on us. I was originally interested in taking these bad boys apart in order to make them into LED bulbs.
zack2475 years ago
your mention of the mercury reminds me of a time when one of my friends accidenally bumped a cfl bulb. when it didn't turn on, he just threw it out. a couple days later, his mom was throwing up because of the mercury and other toxic gases that were just floating around
 omg was she okay? I just broke one and I'm freaking out cuz I slept in the room all night and I didn't know it was broke D:
yeah, she was okay, she just felt a little nauseous for about a week or so. dont worry, you arent going to die
I took apart a broken one and could not believe all the electronics on the little board. I can see whey people said they could make radios and all kind of stuff with one. When you learn about science, you look at things so much differently. So glad I took physics in college.
virgo5 years ago
Thanks , instructable was very educative.
OBar5 years ago
That is where they get the term, Mad as a Hatter, (yes Dawp, I dated myself too) 
joinaqd6 years ago
how much voltage would you say the CFL needs to operate?can it work with 330 volts from disposable camera?
westfw (author)  joinaqd6 years ago
Now THAT's an interesting question. CCFL inverters like the one shown tend to provide more than 330V, at least for "ignition", but they don't need much more than 110V to actually run. (The whole "startup" thing is complex in fluorescents.) Disposable camera inverters are not very efficient, and don't put out very much power overall, but it WOULD be neat to get any light at all out of a CFL from a 1.5V battery!
I've tried to use a CFL off a capacitor, It won't work unless you can have a higher voltage to strike it, I used a piece of wire connected to the trigger transformer to light the CFL.....
i've seen joule thief circuits built to power a CFL from a 1.5 volt battery. it's sweet.
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