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

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.

Caution

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.

Comments

[james34602]

I use this circuit for my flyback transformer driver

[ilovegm]

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?

[Inducktion]

what can you do with the spaghetti stuff? :0

[Itchyzombie]

You eat it.




Just kidding ;D

[Juxe]

It's a flexible, heat-resistant insulator. It's convenient for big capacitors on small boards, to spread out the components.

[ParagonShepard]

So could you put a correctly sized capacitor in parallel with the flourescent tube and correct the terrible power factor in these?

[iamdarkyoshi]

no because fluorescent tubes have to have ac current, or the mercury gathers on one side.

[ginbot86]

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]

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_moran]

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]

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...

[gordzooks]

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.

[laci37]

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.

[rcisneros]

True. Also it's not that much mercury. There are higher level of mercury it some fish.

[dawp]

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.

[bricabracwizard]

Yes, I remember being allowed to roll it around on our hands - that's really going back some!! I'm almost 60 - phew!!

[DELETED_Noah feasey-kemp]

(removed by author or community request)

[laci37]

Mercury is dangerous if you work with it for years, becasue it won't leave the body

[xerxesx20]

That's right, it's an accumulative poison. The odd amount won't kill you though, the same can be said for radiation -- within reason Rumour has it that in the past it was used as to "cure" many ailments and made your teeth both translucent and green, wish I could remember where I read that.

[SKYNET 2.0]

People in the Victorian era put Thorium and other radioactive things into toothpaste and cosmetics, they thought that anything as energetic as radiation would have to be good for the body. Mmmmmm...Thorium.

[sml156]

Since we are on the subject of toxin's substances and unseen radiation has any ever done a study of the effects of WiFi `s . I think that someone should see if pumping all those 0``s and 1 `s into our environment have any ill effects

[BOOM5601]

The 0's are not a concern. It's the deadly 1's we gotta watch out for.

[xerxesx20]

Yes, indeedy. Watchfaces were often treated with tritium, the "tritium girls" as they were known (I think that's right anyways)(the lasses who applied it to the hands and faces of said watches) didn't live long and sometimes put it onto their hands or teeth as a practical joke. Mercury is still poisoning people today in one of OSRAM's facilities in China -- I read about this recently in the press -- though you can't always believe what you read!

[BOOM5601]

Tritium is a more fun isotope of hydrogen. Not only does i still go boom, it's also radio-active! And it was radium on the watch faces. They were tought to put the brush in their mouth to straighten it out for more delicate painting. Mmm, radium.

[rexmo]

it was not tritium, it was Radium.

[1BigKid]

I often wondered about the Tritium. The Night Sites on my work gun, a Sig Sauer p220, are manufactured by Trigicon and use Tritium as it's power source. They are encased in metal and what appears to a thick plastic dot (maybe glass) I don't know how long these sights have been in production or their intended shelf life but I was issued this firearm about 5 years ago and they still glow very brightly in low light situations! I suppose it is like everything else though, they sell it and say it is safe but 20 years later they will tell you it causes cancer or something! I know we strayed off topic a bit but it is interesting anyway. A true conversation piece of an Instructable!

[rexmo]

tritium is not nearly as dangerous as radium and has a much shorter half life

[barrywilliams]

Watch faces were treated with radium not tritium and they were "radium girls".

[xerxesx20]

Aye, thankyou. I realised my mistake after posting, it just didn't sound right if you know what I mean. :-) Hence.. radium jaw -- NOT tritium jaw. lol

[westfw]

Isn't there still thorium in gas lantern "mantels" ? And don't forget that lovely "uranium glass" and "Fiestaware" pottery containing uranium and produced up through the early 1970s... Of course, the resulting radiation poisoning wiped out the entire American upper middle class during that time period. So sad; they should have known better!

[SKYNET 2.0]

I remember the infamous fiesta ware. My grandmother kept a set in here bunker-like basement, on day my uncle took a Geiger counter down there to see if we had a radon problem, and the thing crackled away when he set it on the bow of fiesta wear. The offending box was promptly encased in concrete.

[SKYNET 2.0]

Her* not here

[xerxesx20]

Actually uranium glass may still be made, any radioactivity is contained within the glass. It occurs mostly in the green glasswares you see, though many other doping compounds (colourants) are used. As for flame-mantels (I know the ones you mean) i'm reasonably sure they aren't made any with thorium any more, though I could well be wrong, it wouldn't be the first time!

[Peeet]

Radioactivity is definitely NOT contained by glass. The uranium itself is but not the radioactivity. Danger from radioactivity is measured by 3 factors: level of dose, proximity and duration. Some old wrist watches had alarmingly high levels of radioactivity as tested by my scientist brother. This is of concern as proximity is obviously very close and duration of exposure is potentially very long. Old green transparent glass can be radioactive.

[xerxesx20]

Thanks for filling me in there! I suppose the level of (alpha is stopped by pretty much everything that's thicker than paper, so we'll un-complicate things and forget about alpha for now) gamma, or beta recieved depends upon the thickness of said insulating material also how long the person is within range/proximity to the not-very-well entombed source. Interesting that old watches and some glasswares are still radioactive, "uber" long half life I suppose -- difficult to decide how long the half life would be without knowing exactly what radioisotope of uranium it is. I have seen recently a boost in sales of a small transparent quartz/glass/plastic chamber that has a minute amount of tritium gas inside, a so-called "long life" light source without a switch. They are generally traded as keyrings, but are quite costly. £6-8. ($10-15) I was considering buying one, but I have to be careful of my money at the moment, Leadpumper is becoming rather in need of a good service/rebuild. So that's got most of my dosh for the minute!

[dawp]

Hi: Over 10 years ago i got a Mb Microtek watch. It had tritium numerals and hands. It glowed beautifully in the dark; try it in a cave when they turn out all the lights. The guides get mad about that:) In any case, i haven't died of radiation poisoning and it is still glowing in the dark, but not as bright as new. The half life of tritium is around 10 years. The only watch i know of that currently advertises these lights is in Cabela's catalog. I forget the exact name of it. People and regulatory agencies have a fear of the N word and it is generally difficult to get light capsules. In space they are called "Beta Lghts". I think they have also been used in nautical buoys.

[Peeet]

"i haven't died of radiation poisoning" I'm glad to hear it. There is always a chance that some people will be unaffected by general risks. The fact is that less exposure (which is determined by intensity, proximity & duration) to radiation equals less risk of cell mutation. It is not an irrational fear by regulatory bodies just to make life difficult for us. Some smokers live to ripe old ages, but the vast majority have health effects.

[DIY-Guy]

On the original thread:
Kudos to WestFW for a nice -ible on CFL parts.

On the divergent thread:
Tritium is fine IF it's encased safely. Watches with tritium hands have been designed to keep it inside. Regulatory agencies are not always driven by science but often are driven by public outcry and ignorance. Ask a n* physicist who works with those things and they'll tell you the gas lantern mantles and watch hands scare is pretty much just that, scare tactics. Moral- don't grind up any of those things and eat them.

What a great spelunking tool to bring on the tour, a watch face that won't stop glowing no matter how dark it is or how long it has been in the dark!

[westfw]

Don't forget that common potassium is radioactive too.

[xerxesx20]

Surely not all forms of it are? There's more than I thought: "There are 24 known isotopes of potassium." -- According to Wikipedia (I'm too tired for "proper" research. lol It's also got a Moh's hardness of just .4 ! Talc(um powder -- it's the same stuff at the end of the day, just smashed and crushed up.) is 1.