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Frequency Fluorescent Lamps
Lamp tubes that continue to run for a very long time, even after the filaments have gone!
Normal fluorescent light fittings run on 240 volts 50Hz or 110 volts 60Hz and last quite a long time, but it may be possible to extend their life to much longer by changing the frequency to say 15kHz or 20kHz or maybe more, and yet keep the voltage about the same.
The idea is that at such frequencies there is no longer the requirement to have any filaments in the ends of the tubes. If this is true, it would mean that the fluorescent lamps could not fail just because the filament has snapped. Also, if you had such a light fitting, even if the tube failed, for example while you were practicing with a sword, you'd be able to replace the tube with a "blown" one out of someone else's dustbin!
Using high frequency AC to power fluorescent tubes and other things was a crazy notion a while ago, as it was quite tricky to generate power supply quantities of high frequency electricity without some heavy engineering. Later, with computers running on SWITCH MODE power supplies, the technology has been refined and is now usable.
What happens in a computer power supply is the mains is rectified, ie turned from AC into DC (see AC and DC), and then split up again into high frequency AC. This can then be transformed using a small ferrite transformer rather than having to use a heavy iron core.
As time and technology have gone on, power supplies have become smaller and more powerful.
Also the efficiency has improved. In the 1980s it was possible to get 240 volts AC from a car battery by using an INVERTER, but these were big heavy boxes with not a particularly high output. Now it's possible to get inverters which have a higher power output, and one reason for this is the efficiency of the electrical engineering in the inverter / power supply.
It may be that it's now possible to build a small efficient unit which can convert mains to 20 kilohertz at the same voltage and run fluorescent lamps. It may even be possible to make the unit so compact that it can be made to fit into the base unit of an economy lightbulb. As these energy efficient light bulbs are fluorescent lamps in another form, the idea should apply to them as well as to the long tubes. This could result in energy efficient lamps which have very long lifetimes.
Also see long life lamps and the escape from the 1000 hour tradition.