Old CRT monitor or TV is a great source of electronic components that can be used in DYI constructions. One of them is a flyback transformer that can provide 10-30kV output. The input voltage can be in a range from a couple of volts to over a dozen of volts, power consumption is a couple of watts. In my construction input voltage is 9V, power consumption is 5W.
A flyback transformer is driven by one or two transistors that should be also extracted from the same TV or monitor, those are high voltage transistors, that are hard to substitute and if bought separably can be expensive.
Waring! The device uses high voltage that can lead to injury or death when used inappropriately. Don't touch it when power is on.
Waring! The device produces small amount of UV rays and X rays, don't look into the arc for a long period of time.
Waring! The device produces an arc that can ignite surrounding objects, don't use it near to flammable substances.
The electronic circuit
When current flows though L2 (Q1 is opened) then flyback transformer collects energy (as the magnetic field). When current stops flows (Q2 is closed) magnetic energy transforms into electric energy. Q1 opens and closes periodically because it's base is driven by a generator made from R1, R2 and L1.
|R2||22R + 4R7 (adjust if needed)|
|L1, L2, L3||flyback transformer (an article about how to find the primary and the secundary coils)|
Experiments with high voltage
An interesting device that can be build is Jacob's ladder and consists of two electrodes made from long wires formed in a V shape. When the high voltage is applied, an electric arc creates on the bottom (where the air gap between electrodes is smallest). When the air around the electric arc heats, it goes up like a balloon and also moves up the arc. When the distance between electrodes is too long, the arc breaks and the whole process repeats.
High voltage can be applied to a Fluorescent lamp, note that the lamp isn't electrically connected, but it emits light due to a high difference of potentials between its ends. For a picture in daylight that shows more details, click here.
Articles about similar high voltage constructions
- 10-30kV TV flyback driver with 2N3055
- A Transistor Driven Flyback Transformer
- Flyback Driver Circuits - useful theoretical aspects
- Flyback Transformer Driver - 555 timer used as a driver
- Flyback Transformer Drivers