Sunday, 17 July 2011

High voltage experiments: Part 1- Flyback transformer

I admit that i am a very detailed learner and experimenter, who appreciate the fundamentals more than going straight to the target or subject i want to study. Thats why, you will see several experiments before i move on to making my own version of Tesla coil.

One of them that i ve been planning is two high voltage experiments using flyback transformer; one is salvaged from old television ( part 1, which is this entry) and one made by myself ( the ensuing part 2)

Flyback transformer is a special resonant transformer invented to generate high voltage, high frequency current. This transformer is mostly used to control the horizontal deflection system in any visual devices such as television and pc that are using CRT or cathode ray tube. That is why if you want it, as an alternative to buying from retailer or internet, u can also salvage it from old aforementioned stuffs.

Nowadays, its getting harder and harder to find old television and pc that has this kind of transformer since most of nowadays tv and pc are using LCD screen, so flyback transformer has no market at all ( msot companies stop producing CRT-based tv and pc from 2010 onwards, see wikipedia). Therefore, if u manage to get one, value it! I was so lucky yesterday when i was wandering around the rag market in the town searching for a used television, an old man was having it and sold it to me for about 10 pound. Besides flyback transformers, I also got other useful components for my other projects from the old tv such as speaker, electronic components and the second-most wanted stuff: the cathode ray tube ( so I can play with high freq voltage on it!)

By using the previously outlined circuit that used battery charger transformer to get sparks , i just substituted the transformer with the flyback transformer I got from the old tv. The pinout of the transformer is as follows:


I got longer blue/purple sparks between the electrodes of the transformer's secondary, which is between 1cm to 3cm. Since my multimeter could not load high voltage thus i just reckoned that the voltage is about between 10 to 20 kV. Here are the photos taken:

Overall setup. The battery pack is actually 12V, there are other five cells under the three. The black bulky object with medium length fat wire is the so called flyback transformer. The fat wire is the outlet of high volt high freq current. Notice there is a 10k potentiometer. I substitute it for R2 in the 555 timer inverter diagram before. There is also heatsink where the MOSFET is attached to ( MOSFET cant be seen in the photo). The purple wire stretching out from beneath the transformer is the ground of the hi volt outlet. Please ignore the yellow wire in the picture,including the one wound on the transformer.

Purple wire is lengthen ( using additioal wire, thin yellow wire in the photo, now ignore the thick yellow wire wound on the transformer) to a spark gap, where the fat wire is also attached to its other end. The black rod is just fix the fat wire and the spark gap wire together and serves no other purposes. Two thin yellow wires from beneath the transformer are linking it to the main circuit on the breadboard.
Two medium size wires from the upper part of the transformer are not used.

Ready for experiment.

Closer look on the spark gap, where the spark will be observed.

and here are them:

Next post will be using my homemade flyback and better kind of power supply for more powerful spark.

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