Make cool gadgets from a deceased fluorescent lamp

Do you have some deceased fluorescent lamps? If Yes, then you might still recycle some of its guts to fashion some simple yet usable circuits.

Step 1 Car to portable MP3 player power supply

The first gadget is a 12 V to 1.8 V power supply, also known as step down or buck dc-dc converter. These type of SMPS (Switched Mode Power Supply) are very efficient in terms of energy loss by heat dissipation compared to the linear type (circuits like 7805, 7509, LM317, etc). This works under the principle of energy storage in a magnetic field and then just regulating the output voltage by means of duty cycle control on a PWM (Pulse Width Modulation).


Open up your lamp and look for a small ferrite core transformer (some brands might have two, so try different brands or sizes)

Comments

[hd196]

This site has spms step down regulators schematics with only 2 transistors:
http://www.romanblack.com/smps/smps.htmhttp://www.romanblack.com/smps/smps.htm

very interesting

[acmefixer]

I built his very interesting circuit. But I found one problem with it, The circuit depends on itself for oscillation. If you put a few hundred milliamps load on it while it is running, it will work. But if you then turn it off, and turn it back on, it may not oscillate. Instead of getting 5V out, you then may get 12V out, and that is VERY bad.

If you use his circuit, you should include overvoltage and overcurrent protection.

[hanelyp]

Looking over the diagram, if the output voltage is above the zener voltage minus the base-emitter drop of Q2, Q2 is shut off, denying base current for PNP Q1, turning off the feed from the input voltage.

[acmefixer]

I didn't investigate to find out the cause. One thing I remember is Q1 got hot so I decided to use a heftier transistor, might have been a BD135.  It may be that the emitter to base breakdown voltage of Q2 is being exceeded, and it starts to conduct.  Perhaps you could build one and see for yourself.

[hanelyp]

Replacing a BC327 PNP transistor with a BD135 NPN transistor would be expected to not work.

[acmefixer]

My error, I should've said BD136.

[unknownpocketnerd]

Yes, they are great. Just 2 transistors and it is self oscillating.

[acmefixer]

The Schottky rectifier could be a 1N5819 if the current is not too high. This diode is limited to 1 amp max. There are 3 amp versions, 1N5822, I believe

Warning. There is no current limiting in this circuit. The input should have a fuse.

[Sagar Gondaliya]

can you put in a "real" schematic insted of this hand drawn one?

[unknownpocketnerd]

Sorry, I used a DOS version of ORCAD then printed them and scanned them. My old matrix printer is mechanically damaged. Freeware for electronic design are very limited in their libraries of symbols. Do you have a link to a good piece of freeware that has a good bunch of symbols?

[acmefixer]

ExpressSCH is a part of ExpressPCB, freeware from expresspcb.com. It doesn't have a very good lib, but with a little time and effort you can make your own. I've also used the other part, ExpressPCB, to design PC boards, but you are limited to using their services for making the boards.

[cyberpageman]

I think your schematics are great. It's a pain to draw them by hand and you did a nice job.

I've tried TinyCAD, which is free and easy to use for schematics. http://tinycad.sourceforge.net/

[spacemoose]

I had a look at dai, which I personally use for UML drawings. It seems to have all of the symbols which you need, and I find a pretty usable program.

I have access to Illustrator through work, and i do a lot of technical drawings: Scientific figures, documentation for code and applications. In the situations where it is applicable (UML diagrams, electric circuits) it's my first choice application. It's simple and provides just the important features. This makes it quite efficient and easy to use for the kind of stuff I need to do.

It's a really old school drawing program, orginally implemented under X-Windows, but it's recently been ported to Gnome. There is apparently a windows version: http://dia-installer.de/index_en.html
It is of course GPL'd.

[spacemoose]

whoops, I should have proofread more closely. In the second paragraph, my intent was to say that DIA is my first choice application, rather than illustrator. I only whip out illustrator when I have to something kinda fancy.

[unknownpocketnerd]

Thanks. By the way, I have all of Forrest Mims' Engineer's Mini-Notebooks, by Radio Shack. Forrest drew them all by hand, no typing, no CAD, just good old fashioned schematics. I think this series was his Masterpiece. So I try, in my own way, to emulate him. I don't like to use computers for everyting, except for programing, but computer drafting seems a bit constrining.

[acmefixer]

Don't try to emulate him. I also have most of his manuals. Beware! You will most likely be very frustrated when you build from his schematics and find that it doesn't work. They are full of gross errors and omissions

[cyberpageman]

Yes, your drawings are very similar to Forrest Mim's sensible schematics. I have many of his notebooks and value them.

[bit_bucket]

Great guy still living in TX with his family, Did you know he corrected NASA and a temperature calculation used in global warming with electronics he built on his farm? The joke at the nearest radio shack when parts are missing like LEDs is that the last guy in the store was him! I keep missing him lol

[cyberpageman]

Thanks for the clue. Because of what you said, I looked him up on the Internet. He has a couple of websites, http://www.forrestmims.org/ and http://www.forrestmims.com (which sells his books), as well as several science sites. Amazing guy.

[Sagar Gondaliya]

I use a software called ExpressSHC which has a bunch. it has all the symbols that you have on your schematic plus more. look it up on google. the download takes like 10 minutes but its free and works great. also, if your a really big electronic geek like me, the program automatically downloades a program called ExpressPCB. you link your schematic to it, send it to the site, and they send you a printed circuit board for it.....for a price of course. I used it to make a bunch of tv remote jammers (KipKay) and it's a lot easier to use than veroboard.

[rcisneros]

Thanks for the tip. I never thought of looking inside a cfl for a toroid ring

[mr smart]

is there a way to make this into a dc to dc high voltage transformer ?

[unknownpocketnerd]

Well, you'll need to do some calculations to guess the winding ratio. Or you can make a boost converter.

[zippoge]

i think you forget pin 6, it must be connected with pin 2 

[unknownpocketnerd]

you're right!  Sorry for that inconvenience.  Folks, please acknowledge this tip:  Pins 2 and 6 are wired together.

[rocket scientist]

no ofense but you need to be a little more explanatory cause most of the stuff i didnt understand

[Redgerr]

gona take some appart, dont wanna get any mercury in me though, gotta watch out

[cantthinkof bettername]

Be careful, those compact fluorescent bulbs contain mercury. Did you know that Incandescent bulbs will be banned in Ireland starting March 1st?

[vince086]

don't think it ever went into effect, I was at tesco the other day looking for light bulbs and I think I saw Incandescent bulbs.

[madhops0620]

I heard that somewhere, maybe on the news or somethin. Also, your right you have to be really careful with these bulbs because they do contain mercury

[Plasmana]

They are also banned in UK, and many people are going crazy about getting the last bulbs from the stores...

[cantthinkof bettername]

I think their goal is to be environmentally friendly, but I don't think most people properly dispose of them. Also have you ever read the instructions on what to do if one breaks? It's ridiculous.

[Plasmana]

No, I have not seen the instructions, can you post me a link?

Whatever their plan is, the ban of the light bulbs turns out to be disastrous for many people.

[cantthinkof bettername]

I don't know where they are, but I think they're on the light bulb package. I'll look for instructions now..... Found them. http://www.epa.state.oh.us/pic/cfl_info.html#break

[Plasmana]

Damn, that is really crazy, you even have to pay a lot of money to get rid of them! ^{I just simply take them apart. :-)}

[Lord Kanti]

which component(s) contain mercury and how plausible is it to extract these components without exposure to the harmful vapors?

[bobhill125]

u could of died from the murcury in the bulb ur luky u didnt

[build a BOOM]

sorry to say but mercury is not really the biggest threat to your health yes You really shouldn't mess around with it or break cfl bulbs or tubes. But mercury wont kill you. Oral thermometers all used to have it and most people (that I know)40 and older have broken mercury thermometers, even in their mouths ( accidently ). And they do not have any symptoms of mercury poisoning at all.

[professorred]

There is nowhere close to a lethal amount of mercury in a cfl.

[rcisneros]

True. People are just trying to scare others. Or are stupid. If people looked at the different levels of mercury in different objects, a CAN OF TUNA, will give you more mercury than a broken CFL. Assuming you don't eat the CFL, just exposed.