I had not planned to do this post entry, but when I accidentally dropped this compact fluorescent bulb, (CFL). I had to disassemble it to see what "makes it tick". Of course, I had a good idea about the technology, but had never taken one apart.
There have been two controversial questions about CFL use. The first was the much higher cost vs. cost of operation or efficiency, and the use of mercury in the bulbs. There are two types of CFL's, integrated, and non-integrated. The non-integrated are simply bulbs that can be replaced in an existing fixture with a ballast in the fixture. But, the type in the photo is an integrated type with the ballast enclosed in the base of the bulb. This configuration allows it to be placed in a fixture that was designed to accept the older incandescent type bulbs. The reason for replacing the incandescent bulbs is fairly simple, as incandescent bulbs take the mains voltage, 120 Volts AC in the US, and heat a filament in the bulb, and in the process, give off light. But, the bulbs give off more heat than light, and so, are very inefficient. They also have a relatively short life before having to be replaced. So, we have known for a long time that fluorescent technology is more efficient, but in the typical format that is a long tube with an external magnetic ballast, they had limited utility in the home. But, CFL's have changed that completely. So, what is a ballast, and how do they work? Lets take a look! The two photos below are from my broken bulb and show the ballast, and in the second one, the reason for probable failure. Heat!:

The electronic ballast found at the base of the CFL contains a small circuit board with diodes to rectify AC voltage to DC, a filter capacitor to smooth ripple, and usually two switching transistors, along with a toroid or transformer. The incoming 120 volts is first rectified to DC, then converted to high frequency AC by the transistors and the transformer to form a resonant DC to AC converter. This high frequency AC is fed to one electrode at each end of a glass tube or bulb. The bulbs contain an inert gas, argon, at low pressure. A small amount of mercury in the tube vaporizes, and causes it by ionization, to give off ultraviolet light. The inside of the tube is coated with a mixture of phosphors, which when excited by UV light, produces the white light. As a crude test of the phosphors, I illuminated the broken tubes with three types of ultraviolet light: UV A, B, and C, which is the UV found in germicidal lamps and has some dangers. With both UV A and B, I saw a pink color, and with UV C, it was white. Although not conclusive, the frequency of UV generated in the tube may be a special frequency of ultraviolet.
There are two points of interest that should be noted: The second photo above shows black areas that suggest exposure to high temperatures. This bulb was located in a recessed ceiling fixture and had very little air circulation. This will shorten the life of the CFL. They should have some open area to dissipate heat. The second is the mercury. Although the amount is small for each bulb, when several million are disposed of, the amount becomes more significant. Please recycle as the manufacturer suggests. The is a great deal of information on the web including Wikipedia, but there is a general article located here. Let there be light...

Video Below:
There are some experiments that require equipment that is either too costly, or may only be used infrequently, as in the case of a centrifuge. Occasionally, I need one, but try to get around the problem in another way. But, I decided that it was time to make one myself and end the "alternative solutions" trying to get around the use of a centrifuge. This is the result of some considered thought and limited resources. For this experiment I wanted to work with extracted chlorophyll and check the fluorescence with a small UV LED flashlight. As you will see in the video, it worked fairly well.
There are many designs on the web but none seemed to be what I wanted. This build is extremely easy and allows for several alternative materials. For example, if aquarium tubing is not available, any flexible tubing from the hardware store will work. It can be purchased by the foot at a really low price. The only important factor is that the tubing has to be sized to be flexible and capable of being a forced fit for the dropping pipette. The other piece of this simple centrifuge is the knurl on the shaft of the motor. The tubing has to have something to "grab onto" and it could be a knurl, a flat spot, or a tiny gear. Balancing can be "trial and error" or small weights that can be moved to compensate. I found that if the tubing assembly is fairly accurate in distance from the shaft, and the fluid in the tubes are close to the same weight, the balance is fine. There are a couple of thoughts before the video and the included links:
I have posted this project in good faith, but there are always safety issues with anything that is spinning at 4000 RPM's. The safe and careful operation of this device is the responsibility of the reader. I can assume no responsibility for your safety. I have recommended plastic pipettes and not glass as there is greater risk with glass. Always use a container of some type to enclose the centrifuge. Now, on with the video:

Almost any 12 volt motor will work but  the link to the motor that I used is here. If the link is broken, the product may not be available, but there are many DC motors  at the Electronic Goldmine. Check the column on the left at the home page. The dropping pipettes can be found at some drug stores but also at American Science and Surplus. I could not link directly to the product, but just type in "plastic pipette" in the search our stuff  here. For the extraction of chlorophyll from spinach leaves, check here. Lets go for a spin!