Tuesday, 19 July 2011

High voltage experiments: Part 2- Homemade flyback transformer.

As i ve said before, in this second part i will show you my high voltage experiment using my own hand-wound homemade flyback transformer using the ferrite core from the original flyback transformer salvaged from old cathode ray tube (CRT) television monitor.

Before I move on, here are the photos taken and descriptions:
The overall setup. I ve changed the power supply from stacks of battery into regulated laptop power supply (indicated by black wire on the left) that can safely adapt power from the mains for project purpose. It supplies 9VDC at 3.16 A. I ve been using same inverter circuit i ve always been using before, except that for R3 i use 500 ohm, R1 at 3kOhm, and 10k potentiometer for R2 for easily varying the operating frequency ( pin 7 of 555 is connected to swiper, pin 8 to one of the end pin while the other end pin is left unconnected, so this potentiometer is modified into varistor rather than potential divider). Also to protect the mosfet i ve put a snubber diode 1N4148 in series with 464kOhm resistor, across the primary winding of the transformer, between the supply line and the mosfet's drain pin.

Closer look on the circuit. I use copper heatsink ( the finned chunk of brownish thing) for protecting mosfet from overheating.

Closer look on the left side.

Closer look on my homemade handmade flyback transformer

This is the original flyback transformer from old CRT tv monitor.

...and this is how the double C ferrite cores are dismantled from the transformer.

The primary winding. I made it to be fitted enough into core. First I take an old pamphlet paper ( since its not too hard) then i rolled it around the core, and I retained the cylindrical shape of the rolled paper using common tape. Then over the cylinder, i rolled one layer of PVC tape, and the purple wire. I added another layer of common tape so the purple wire coils firmly positioned on the red PVC tape. Notice i ve used 15 turns, but its up to you to use any number of turns as its only affects the amount of current u 'll get on the secondary.

Bird eyes view of the primary

The secondary coil. Same method with the primary ( also made to be well fitted on the cylindrical structure of the ferrite core), except that i used 25SWG ( about 0.5mm diameter enamelled copper wire) for the winding, with about between 30 to 40 turns per layer, and i ve had about 10-12 layers for that ( I dont quite remember), so there are about 350 to 400 turns overall. I am still using PVC tape and common tape for each layer. More on this design of secondary can be found here.

Bird eyes view of the secondary.

The components ready for assembly.

And it really works...

See ya next time.

p/s: after several times using the power supply, the 555 chip was damaged and i have to replace with new one. This maybe due to high current surge since i m using 3.16 A. Therefore I recommend you to put resistor (for example 500 ohm) between the supply line and any direct input from the supply into the 555 ( pin 4 and 8). To date, i connect pin 4 and 8 together, and link the node to the supply with a 500 ohm resistor. Though the spark becomes shorter, this method may prolong the 555 lifespan and u may still have fun with the spark.


  1. Saya suka yg buat transformer tu. macam penah tengok. Tp saya suka ttg keseluruhan experimen pasal 'tesla' nih.

    sdra uji tak jika ada medan magnetik yg wujud di skitar 'spark' tu? Ada apa2 gelombang yg terhasil? It could be important.

    i'm following :)

  2. Without doubt, the wave generated must be radio wave ( since i was using radio frequency). I just hypothesize it since i m lacking special tools. Fyi,every radio frequency spark must generate radio wave as shown by Nikola Tesla n Heinrich Hertz ( you should read more bout radio frequency). Sometimes infra red (if the spark generates too much heat), ultra violet , and even x ray, can also being produced. Its all dependent on the frequency used. To obtain relationship between frequency n type of wave from spark, simply fiddle around EM spectrum.