Introduction: Salvaging Parts From Burnt Out Mini-fluorescent Lamps

Many useful electronic components can be salvaged from burnt out Mini Fluorescent Bulbs. The components are located in the lower part of the bulb. The circuit ( an AC frequency converter) takes the 50 or 60 cycle AC from the line, turn it into DC and then turn it back into high voltage, high frequency AC to excite the Mercury vapor in the bulb thus forming an arc and giving out Ultraviolet rays and in turn exciting the Phosphors (Phosphorous based electro-sensitive chemicals) coating the inside of the bulb. These Phosphors when hit with UV light, give off visible light of a color that is determined by their chemical formulation. The 2 transistors that are contained in this bulb are rugged and have can take up to 700 volts between the Collector and Emitter at 2 Amps. This means that they can be used in many high voltage driving circuits. The 200 volt electrolytic capacitors are very useful to people who restore old tube equipment as the Electrolytic Capacitors are the most frequent item that goes in old radios and audio equipment. I have put these salvaged capacitors in many old radios and have never had any problems over the years. The rest of the components are useful also but can just be added to your junk box for later use.

Step 1: Obtain Burnt-out Mini Fluorescent Bulb Like This.

WARNING: THIS BULB CONTAINS MERCURY AND NEEDS TO BE DISPOSED OF PROPERLY IN APPROVED BINS AS PER YOUR LOCAL MUNICIPAL REGULATIONS. WRAP THE GLASS PART IN CLOTH OR PAPER TOWEL SO THAT YOU WILL NOT CUT YOURSELF WITH GLASS OR COME IN CONTACT WITH THE MERCURY THAT MIGHT SEEP OUT OF THE BROKEN GLASS. WORK SAFELY AT ALL TIMES! WEAR GLOVES!

Step 2: Cut Along Seam With Large Tubing Cutter

Get a tubing cutter that cuts at least 2 1/2 copper tubing. Wrap a cloth or paper towel around glass part of bulb and cut the seam in white plastic part of base using back and forth motion to completely seperate top and bottom of bulb.

Step 3: Gently Separate Top and Bottom of Assembly

When you have cut through plastic part of fluorescent bulb assembly with tubing cutter, use side cutters to cut circuit board from wires that connect it to glass bulb part and base. Glass part and rag should be disposed of in matter approved in your local juristiction for the disposal of Fluorescent bulbs. Even if glass part doesn't break, assume it is contaminated with mercury and dispose of it anyway. Don't re-use it!

Step 4: Gently Unsolder All Electronic Components From Circuit Board.

Unsolder electronic components from circuit board using mini hemostat. (Obtainable from electronics supply stores). Grab base of component wires with hemostat on side opposite to soldered side and gently pry up while applying heat from low wattage soldering iron. This will prevent heat from damaging heat sensitive parts like transistors and diodes while giving you leverage to pry the component out. I was able to salvage 24 components from just 1 burnt out mini fluorescent bulb. Bigger ones have more and heavier duty components. Here is a list of what is in the picture:

3 Inductors

6 Non-polarized Capacitors: (2) .05 uF, (1) .001 uF, (1) .0027 uF, (1) .048 uF

5 Resistors: (3) 470K (2) 15 Ohm

2 Electrolytic Capacitors: 200 volt, 15 uF

6 Rectifier Diodes: 1N4007

1 Diac

2 Transistor: E13003: NPN Power Transistors

Comments

author
thracian made it! (author)2015-10-27

I did the same thing, one day before reading this article :) I had 10 "old" non working bulbs , two of them were in poor condition, with some parts burned.

Bulb-circuit.jpg
author
GermanA2 (author)2015-10-26

This is a probable circuit used for this lamp

http://www.nxp.com/documents/application_note/AN00...

author
mr electro (author)2015-10-25

My definition of a "Power Transistor" is any transistor that is rated at more than a couple of watts. This device is rated at 20 watts collector dissipation with 1.5 amps continuous collector current or 3 amps pulsed. Basically if it is designed to be attached to a heatsink, I define it as a power transistor. I will agree with you though, this device is definitely on the low to medium end of the scale when you compare it to the high power devices made by companies such as Powerex.

author
Gelfling6 (author)2015-10-20

The tubing cutter may be an overkill.. Most are usually sealed with a small amount of Cyrano-acrylic glue, and the old "Corner-Cracker' idea for old wall-wart power supplies might work, but as noted STILL be careful not to break the tube! Simply place the plastic casing between the jaws of a vice capable of opening to the required 2-nch width, on the sides away from the tube ( -> (8) <- the 8 being the two parts of the tube going through), and just slightly below the separation. Then, with the tube still covered in cloth (as shown), SLOWLY close the vice jaws, til you hear the plastic go "Crack!". (the sections separating)

author
posteljooni (author)Gelfling62015-10-23

And I use a small rotary tool to open the case) Many ways!
I sStill have to learn to use the salvaged parts, though) No XP in electronics whatsoever)

author
mr electro (author)Gelfling62015-10-20

Yes, definitely another way of opening it.

author
Sock Puppet (author)2015-10-23

(often) a diac.

http://bit.ly/1RsgCt7

author
mr electro (author)Sock Puppet2015-10-23

I checked out the device in question with a resistor in series with it. I applied about 90 volts peak to peak across the whole circuit and observed the waveform across the device. It shows a symmetrical breakover voltage around 32 volts. It is a Diac.

author
mr electro (author)2015-10-23

Yes the component that I identified as a low value capacitor must be a Diac. Very unusual for a Diac to be used in a Bipolar Transistor circuit. they are usually used in Triac circuits. I came across an original engineering paper from Phillips that goes over the design of the typical CFL driving circuit using a Half-Bridge Inverter. The Diac apparently is used to trigger one of the transistors when the voltage across it reaches 32 volts.

http://www.nxp.com/documents/application_note/AN00...

The theory behind a Half Bridge Inverter can be found here:

https://books.google.ca/books?id=WwXi9LI5W1sC&pg=RA2-PA301&dq=Half+Bridge+Inverter&hl=en&sa=X&ved=0CCoQ6AEwAWoVChMIzKSo_7bZyAIVF0eICh0SngOz#v=onepage&q=Half%20Bridge%20Inverter&f=false

author
Sock Puppet (author)2015-10-23

Looking at a couple of schematics from the net, there's a diac in there too.

author
licheness (author)2015-10-20

I'm going to try this. Have not had a lot of luck unsoldering in the past, but will try again! I like to salvage and have a burnt out CFL waiting for disposal.

author
mr electro (author)licheness2015-10-20

I find that the curved locking hemostat really makes it easier to ease out the leads while you are heating the solder. Amazing how a tool that was designed for holding veins closed while doing operations has such utility in electronics. Good Luck!.

author
FirstSpear (author)mr electro2015-10-23

Absolutely a must have, if you do stuff. Particularly handy for connecting leads to motherboard header pins inside dark crowded computer cases.

author
Phil_S (author)mr electro2015-10-22

Absolutely right. I have about four pairs of these useful tools, curved, long straight and so on. I t beggars belief that veins and arteries were clamped off without doing a large amount of damage, but with blood everywhere, you would use a pair of Mole grips. They are still used for mundane things like attaching sterile sheets.

Over the centuries, surgeons have invented a vast array of extremely specialised tools.

In electrical/electronics, very useful as a temporary clamp on a couple of wires, but where they really come into their own is when that small, essential screw falls into a crevice in the floor and a magnet won't work - got me out of trouble many times.

author
dillonsparks (author)Phil_S2015-10-22

And for getting the last out of a doobie

author
Phil_S (author)dillonsparks2015-10-23

There's economy for you.

author
przemek (author)2015-10-22

Spudge is the technical term for a little pry tool that opens plastic cases. Guitar picks make great spudges; learn to play guitar or steal some picks from your friends (or children---sorry, J). You basically squeeze the sharp corner of the pick inbetween the two plastic halves, or even between the plastic and the glass bulb if you have a R30-type bulb and need to liberate the CFL tube from the glass enclosure. Several picks deployed in several points around the circumference are often very effective. NOTE: wear safety glasses and work CAREFULLY over spread newspaper if you mess with the glass---it's very easy to break.

author
bobwojo (author)2015-10-22

Don't forget LED bulbs, good parts there as well and no mercury to worry about. I've even managed to fix some with bad solder joints.

author
Cicko (author)2015-10-22

A piece of advice regarding the electrolytics: Don't assume that they are good for reuse, because they have taken a lot of heat stress and that heat is shortening their life dramatically. Always measure them with an LCR meter (capacitance may be within tolerance, but the ESR can be way off) before you reuse them or after you desolder them. If the top of the can is bulging, even slightly, dump them immediately, they are no good anymore.

As for other components, most of them could still be good and reusable, but measure all of them before reusing them because (in my experience) almost 90% of the bulb malfunctions are caused by the electronic fault.

Nice instructable btw!

author
mr electro (author)Cicko2015-10-22

Yes, checking the Capacitance and ESR is a good idea. I do this before I put electrolytics in any new project.

author
SolomonT (author)2015-10-22

I have a lotof bured lamp I will trays

author
Raphango (author)2015-10-22

Great!

author
theturn (author)2015-10-22

Great instructable, I'd just like to offer the following wisdom that was passed on to me.

I was (correctly, I now believe) told that a larger rather than smaller iron is better for the components when desoldering : small irons can take quite a while to heat the part up to the point that the solder melts AND the part can be taken from the board, and while heating (especially with any heat sink in the vicinity) the heat can creep up the component legs doing more damage than if a larger amount of heat were applied at the solder point and the part whipped out.

A bit like pulling a plaster off quickly stings less than peeling it off slowly if you like.

Keep up the good work!

author
stechi (author)2015-10-20

Good one! That hemostat thing looks like a pair of surgeons' forceps to me! In any case I have a little clip-on heat-sink took that does the same. I'll definitely have a look in side the next CFL lamp that fails, although I am going over to LEDs

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