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LAN_403

Ash Small

Sat Jan 01 2011, 10:50PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

The MJE13003 is only good for 1.5 amps, again, very small arcs

The datasheet:

tells you which pin is which.

LIGHT

Sat Jan 01 2011, 10:52PM

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so say I have a 9v battery or what ever, where does the - wire and the + from the 9v supply go?

Thanks once again.

Ash Small

Sat Jan 01 2011, 11:05PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Google 'single transistor flyback driver' or re-read your other thread for the links.

You need a couple of resistors as well, but you'll have some from whatever you got the transistors from.

You may need to read up on connecting resistors in series and parallel, and wattage ratings for resistors.

LIGHT

Sat Jan 01 2011, 11:25PM

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I have many times, but I dont know what to do with the 3 pins and the other 2 wires from the 9v supply.

Ash Small

Sat Jan 01 2011, 11:47PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

You need to wind a primary for the flyback, different people say a different number of turns. I used ten on my first one. The positive goes to this. The other end of the primary goes to the collector on the transistor, the negative goes to the emmiter.

You need to wind a feedback coil, I used four turns on my first one. I think this has to be wound in the opposite direction to the primary, but check the other circuits on the web.

You then need to take another wire from the positive terminal to a 240 ohm resistor, and a wire from the other end of the resistor to the feedback coil and a wire from the other end of the feedback coil to the base of the transistor.

most circuits also have a 27 ohm resistor connected between the first transistor and the emitter of the transistor, but some people say you don't need it.

You may need to put another resistor in between the positive and the primary if you use a transistor with a lower current rating to stop it blowing.

You really need a digital multimeter with a transistor tester built in, so you can check if you've blown the transistor if it doesn't work.

Here's a link to one of the websites with the circuit on it.

there are others, and there is some stuff here if you search for it.

Ash Small

Sun Jan 02 2011, 11:10AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I looed up the other part numbers. The STPS2045CT is a shottky diode (2 diodes in one package actually) rated at 45 V and 2 X 10 A. It will be useful for something.

Looks like the 09NO3LA is a power transistor, but it is a MOSFET (I think).

25V and 50A, the data sheet is here:

I don't know enough about MOSFETS to say whether it will work with the single transistor flyback circuit. I'm afraid someone else will have to advise here.

Th3_uN1Qu3

Sun Jan 02 2011, 06:53PM

Registered Member #2614 Joined: Sat Jan 09 2010, 08:57AM
Location: Bucharest, Romania
Posts: 26

A MOSFET will not work directly in the single transistor driver, at least not without modifications. The 13003 will work but it'll overheat and die quickly.

I'd recommend a 555 timer driver and use whatever MOSFET you have on hand with a decent voltage and current rating. I still have my first flyback driver which used a 555 timer, a IRF630B mosfet taken from a 17" monitor, and the flyback from the same monitor. The MOSFET was mounted onto a big heatsink which came from... you guessed where. I ran it for 1.5 hours once without a problem. Power was 12v from a computer PSU, 4 turns on the primary.

The 555 driver is easier to make IMO because you don't have to mess with too many windings, all you need is a few turns of wire (you can use wire from a computer PSU) on the open end of the flyback transformer core, and the 555 circuit can be built on a breadboard then wires extended to the power MOSFET. Start with 6 turns and go down if the transistor is still cool. Less turns = more current = longer arc, but higher risk of frying the MOSFET (or yourself).

quicksilver

Sun Jan 02 2011, 07:32PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

I've used the MEJ13009 quite a bit in the little single transistor designs and they work exceptionally well.
I wouldn't buy the NTE product however.....

LIGHT

Wed Jan 05 2011, 04:59PM

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I'm getting tired of my 11watt and single trasistor driver.

Can someone tell me how to acheive a more powerful arc from another device?

As long as I dont have to spend a bomb.

Any suggestions are OK.

Thanks.

Ash Small

Wed Jan 05 2011, 06:02PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Buy a cheap digital multimeter (about Â£5 from a discount tool shop) and buy one of the transistors that have been recommended (about Â£2), then you can get some resistors out of something. Try and get hold of a PC power supply as well, this will be better than a nine volt battery. This really is the cheapest way to do it, and you will learn doing it. You WILL need a multimeter if you want to take this hobby further.

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