This instructable will show you how to make an audio modulated plasma speaker using a flyback transformer out of an old CRT display, and the all time hobbyist favourite which is the 555 timer chip.
Not only can this circuit be used to produce audio modulated plasma arcs but it functions as a high voltage power source for other projects.
I will be updating this instructable over time.
Note: Please turn up your sound volume, it sounds much better in real life but my camera does not pick it up too well.
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Step 1: What you will need
1x Flyback tranformer
A flyback transformer, sometimes called a line output transformer are used in CRT TV's and computer monitors to produce the high voltage needed to power the CRT and electron gun. They also have other auxiliary windings built into them that power other parts of the TV.
You can get flyback transformers out of older CRT monitors and TV's. They are the ones that have a big chunky chassis. There are also other instructables on this website showing how to remove them from the chassis and circuit board.
1x Power MOSFET,
I used an IRF540 as that is all that I had lying around. I strongly recommended using a MOSFET with a higher drain-to-source voltage than the IRF540, which is only 100v.
Just for an example IRFP460 would be well suited for this and IRFP250N and IRFP260N would also work. Any MOSFET that is rated for high voltage, has a low on resistance and can take more than 15 amps would be fine.
You will need a large heatsink as it will get very hot (more on why later). The TV board you got the flyback from is a good source for heatsinks.
1x NE555 timer chip
I also recommend using an IC socket (8 pin) for the 555 so you can easily remove the chip without de-soldering it.
2x 47 ohm resistors
1x 22 ohm resistor
1x 470 ohm resistor
2x 50K potentiometers
3x 1nF capacitors
1x 220uF - 1000uF electrolytic capacitor (16v will fine).
1x 10nF capacitor
1x 100nF capacitor
1x fast diode, such as UF4007
1x NPN and PNP complementary bi-polar junction transistor pair (if you are following the first schematic). BD139 and BD140 can be used here.
12V power source
Fuse (recommended to protect the power source/supply).
Audio source (This could be an MP3 player or old phone for example).
Solder and soldering iron + some spare wire.
I am in no way responsible if you mess up with this circuit. If you mess up, receive an electrical shock or burn your house down whilst making this circuit you have no-one to blame but yourself. By following this guide in order to make this circuit you agree to accepting all liability if something were to go wrong.