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Intro:
This instructable will show you how to make a cheap and simple driver circuit in order to get high voltage arcs out of a component called a flyback transformer.
A flyback transformer, sometimes called a line output transformer are used in older CRT TV's and computer monitors to produce the high voltage needed to power the CRT and electron gun. They also have other auxiliary windings built into them that the TV manufacturers use to power other parts of the TV, so they are usually customised by the manufacturers.
For the high voltage experimenter they are used to make high voltage arcs, which is what this instructable will show you how to do with just a few simple electronic components.
You can get flyback transformers out of older CRT monitors and TV's. They are the ones that have a big heavy chassis. There are also other instructables on this website showing how to remove them from the chassis and circuit board.
Disclaimer
I am in no way responsible if you mess up with this circuit. If you mess up you have no one to blame but yourself.
What you will need:
1x Flyback transformer
1x 2n3055 transistor + heatsink
1x 220 ohm 5 watt resistor
1x 22 ohm 2 watt resistor
(Note: The resistor values do not have to be exact. Say if you had a 33 ohm and a 200 ohm resistor they would still work fine for this circuit).
Some enamelled magnet wire, single core bell wire also works well too for the primary and feedback coils.
A fast diode. Although this is not needed for the circuit to work, it protects the transistor from back emf spikes and can help prolong the life of the circuit. I just used the one I found on the TV board but the UF4007 is an easy one to get hold of in electronic stores if you need to buy one.
+Some way of connecting the components
such as alligator clipped cables or wire and solder.
You may not, except with our express written permission, distribute or commercially exploit the content. Nor may you transmit it or store it in any other website or other form of electronic retrieval system.
This instructable will show you how to make a cheap and simple driver circuit in order to get high voltage arcs out of a component called a flyback transformer.
A flyback transformer, sometimes called a line output transformer are used in older CRT TV's and computer monitors to produce the high voltage needed to power the CRT and electron gun. They also have other auxiliary windings built into them that the TV manufacturers use to power other parts of the TV, so they are usually customised by the manufacturers.
For the high voltage experimenter they are used to make high voltage arcs, which is what this instructable will show you how to do with just a few simple electronic components.
You can get flyback transformers out of older CRT monitors and TV's. They are the ones that have a big heavy chassis. There are also other instructables on this website showing how to remove them from the chassis and circuit board.
Disclaimer
I am in no way responsible if you mess up with this circuit. If you mess up you have no one to blame but yourself.
What you will need:
1x Flyback transformer
1x 2n3055 transistor + heatsink
1x 220 ohm 5 watt resistor
1x 22 ohm 2 watt resistor
(Note: The resistor values do not have to be exact. Say if you had a 33 ohm and a 200 ohm resistor they would still work fine for this circuit).
Some enamelled magnet wire, single core bell wire also works well too for the primary and feedback coils.
A fast diode. Although this is not needed for the circuit to work, it protects the transistor from back emf spikes and can help prolong the life of the circuit. I just used the one I found on the TV board but the UF4007 is an easy one to get hold of in electronic stores if you need to buy one.
+Some way of connecting the components
such as alligator clipped cables or wire and solder.
You may not, except with our express written permission, distribute or commercially exploit the content. Nor may you transmit it or store it in any other website or other form of electronic retrieval system.
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Signing UpStep 1Mount the transistor onto the heat sink
Mount the transistor onto the heat sink. The heatsink is important as the transistor gets hot. I just bought the cheapest heatsink maplin sell. The 2n3055 is a TO-3 case style.
You can use an insulator pad if you want but I just used a small amount of old thermal grease I had lying around. To mount the transistor to the heatsink I just used some spare screws and nuts I had in the garage.
Make sure that the transistor pins do not physically touch the heatsink and it is screwed in securely.
Q: Can I use a different transistor?
A: Yes you can, as long as the transistor has similar specs to the 2n3055 or better.
Q: Can I use a PNP transistor?
A: Yes, but you will have to reverse the collector and emitter connections in order for it to work. It will also need to have similar or higher specs as the 2n3055 transistor.
Q: Is the heatsink really needed?
A: Yes, if you are wanting to use this circuit for more than a few seconds the heatsink is vital as the transistor will get hot fast.
Q: Can I use a MOSFET?
A: No, a MOSFET will not work for this circuit.
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Have you got any spare computer or desk fans lying around? Using a fan on the heatsink will help.
One way of cutting down the back emf pulses is to use something called an "RCD snubber" across the primary coil, however they can be tricky to get right. And putting anything across the primary coil is going to cause a smaller arc since the back emf (this is where the word flyback comes from) is the only reason there is such a high voltage coming out of the flyback transformer.
Perhaps try putting a small film capacitor across the primary coil, anywhere around 0.47uF-1uF. You will get shorter but much hotter and thicker arcs and it should help reduce the MOSFET heating. You might have to play with the values and flyback frequency (adjust the pots) to get the best results.
As for MOSFET temperature, what MOSFET are you using? They can easily survive upto 150C, although that is with a large fan cooled heatsink.
One last thing, which circuit diagram version are you using? The first one I uploaded doesn't allow for fast MOSFET switching becuase of the resistor between the 555 timer and power supply.
Hope this helps.
I estimate there is no more than 900v-1kV here but there must be around 800mA-1amp in the arc.
Gene
All the magnet wire I have purchased from my local electrical store has required me to scrape off the enamel before soldering. Even with my coil gun project where I was using voltages of around 300V with the magnet wire I still had to scrap off the enamel in order for any current to start flowing.
Maybe someone here knows what kind of trouble?
Thank you
I have made the 555 based driver myself and have also audio modulated it here http://www.instructables.com/id/555-timer-based-plasma-speaker/
But I have also found that the MOSFET's and the NE555 chip tend to die easily in that set up. If you know a way of keeping the NE555 and MOSFET's from dieing then let me know ( :
Try connecting one (in parallel to the supply) anode to the minus of the supply.
This should take the current from the main coil during switch off and prevent overloading the FETs .
Can you send me a link to the schematic you followed?
I have made the ZVS driver and it works very well. I can get 3 inch hot arcs on 24v input. Its definatly a must try if you are into this sort of thing ( :