[SOLVED] I need help on plasma lighter

[jonathen]

Im trying to make a plasma lighter, childish but i don't care. I have this small transformer that has 2 slots, primary and sec coils, but I don't know what voltage i need for the arc. I want to run it off of a 6v or 3v batteries, but i have no clue. The transformer I think was a step down. I tried to do math, thinking 60v would be right, primary coil would be wound 209 times (i might of ran a little less) and the sec winding would be 2029 (somewhere around there). Will that make 6v to 60v?
Am I right with the 60v anyway, and i might just be wasting your time, sorry. (about 1/8in or 3.17mm would be the gap) The core is 1 cm by 1.1 cm, I don't know the size of the wires, one (im thinking the primary) was like mm or smaller, but the other one WAS way smaller, less then normal thread. Rember im a bloody noob! This transformer came from a 4-6v battery charger, for rc cars (not the GOOD rc cars, the crapy one's, Newbight brand i think) Lastly what kind of components would i need, mosfet? diode?????

 

[betwixt]

Well - forget that transformer!

The voltage for a reasonable arc will be around 2KV so such a small transformer would simply spark between the wiring and core. You need one with a split core, preferably into several sections side by side so the voltage can build up between them but they have some isolation against flash-over.

Note that all transformers work on the principle of creating a changing magnetic field through one winding and converting it back to voltage in another winding. A battery produces DC so apart from an extremely brief pulse as you disconnect it and the magnetic field collapses, nothing will come out on the high voltage side. You need to convert the battery voltage to AC or at least pulsed DC before the transformer does anything useful.

Brian.

 

[jonathen]

Where could I salvage (not buy, unless you want to buy me one) one? Clarifying the transformer I have looks like
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------- Crude but should get the point across. Is that the wrong one?

Lastly Thank you for replying, and wasting your time on me. How could I get dc-ac. In one of the videos they show them rewinding it, using (i think) a mosfet, resister, and a diode

 

[jonathen]

Kilovolts? (yes I know the metric system, and what a volt is)

- - - Updated - - -

Sorry, nvm (video was https://www.youtube.com/watch?v=s6NyTprQCBI)
It said the constant 42, what dose that mean. And by the way, im not doing a diy, i have a small transformer

 

[betwixt]

The easiest way to do it without going into technical details is to make a single stage oscillator using a MOSFET (IRF630 or IRF830 for example).

Sorry about the image quality!

The three windings are on the same transformer core. The one to the MOSFET gate should have 10 turns, the one to the MOSFET drain should have 10 turns and the high voltage winding should have as many turns as you can fit in the space. IMPORTANT: wind the gate and drain windings on one half of the core and wind the high voltage on the other half. It will help if you add a layer of insulation Scotch tape or PVC insulating tape after every two or three layers of wire on the high voltage side. This is because each turn of wire has an increasing voltage on it and the insulation on the wire will flash through at a few hundred volts. If you layer it, there is less chance of a high voltage between adjacent turns causing a problem. Use thicker wire for the drain winding if possible. For the other windings the thickness isn't important and of course if you use thinner wire you can wind more turns on the high voltage side. I have not calculated the optimum number of turns for the gate and drain windings, that would be impossible without full details of the transformer and it's core material but 10 turns should be adequate.

If it doesn't work, reverse the end of the winding of ONLY the gate coil. Note that the MOSFET might get hot, if it does you will have to bolt it to a heat sink to dissipate the heat. On some MOSFETs, like the ones mentioned, the drain is connected to the metal tab so be aware that it has to be electrically isolated so it doesn't short out and that it may carry enough voltage to give a nasty shock!

Note that MOSFETs usually need a few volts on their gate before they start to conduct so it may not work from only 3V. From 6V it should be OK.

Brian.

Just notice the Youtube link - sorry but at the moment my internet connection is too slow for video streaming so I can't watch it!

 

[jonathen]

Damn, thank you!
One thing, do I have the right transformer. Because you show 3 windings, this will most likely be the last question. Thanks!!!!!!!!

 

[betwixt]

Difficult to see it's size but it should be OK.

Keep the low voltage windings on one side of the divider and the high voltage on the other. I can't stress enough that if you are dealing with high voltages, they will take the easiest path to arc through, which usually isn't where you intended it to be!

When you wind the high voltage side, note the wire end nearest to the core and use that as the 'ground' side so there is less chance of it flashing through the plastic to the metal core or the other windings. After say two layers of wire, wrap a layer of thin tape then continue winding, the tape will also help to prevent flash over and it also holds it together to make it easier to make.

Brian.