High voltage supply (10-30kV) made from CRT television flyback transformer

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 toxic ozone and nitrogen oxides, don't use it in closed rooms.

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.

Waring! Cathode ray tube present in CRT monitors or TVs can implode if physically damaged, be careful not to break or harm it during extraction of any electronic components like flyback transformer.

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.

R222R + 4R7 (adjust if needed)
L1, L2, L3flyback 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.

Jacob's ladder - high voltage spark gap

High voltage supply can be also used for Kirlian photography, that I presented it in a separate article. Below is a regular picture of a leaf and a picture made by using this technique.

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

YouTube films with similar projects made by others


  1. Super ciekawy projekt, można wykorzystać do wielu ciekawych eksperymentów..

    1. Dzięki, to fakt, takie coś może się przydać do wielu rzeczy :)

  2. Kable do cewki mogłyby być krótsze..

    1. To racja, ale już nie chciało mi się ich skracać, a całość i tak wyszła estetycznie.

  3. "To jest genialne w swojej prostocie" :). Czy taki flyback pociągnie lampę ozonową?

  4. Sincere thanks for the article!
    Got so much to learn being an engineering student.

  5. What is the current for the output?

    1. Output current is less than 1 ampere for black and white CRT and 1 and more than 1 ampere for colour CRT.

    2. Sparking gap will depend upon input eht voltage and transistor frequency.

  6. thanks for the information,what i really wanted to know is how can you prevent the high voltage transformer from getting damaged by a short circuit from the secondary side.

  7. Thank for sharing your build of the simple self resonating simple transistor flyback driver, it is properly one of the best to its simplicity and that it is hard to kill from abusing it :)