Flyback powered tesla coil for under 50 dollars. / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

Flyback powered tesla coil for under 50 dollars.

Move Thread

LAN_403

Arcstarter

Sun Jul 06 2008, 11:36PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

What you will need is a tv, a microwave oven, some transparencies(you can get 50 for like 14 bucks, or 100 for 28 or something from office depot or any other store that will sell stuff for laser printer. Also try mannings which is where i got mine.) and some aluminum foil, some wire, a power supply, a few ne555's and mosfets or transistors, some resistors and capacitors. You will also need some screws for a spark gap and either two 'l' brackets or just some metal bent into an 'l' and some holes for putting the screw through.

First you want to build the high voltage source of the tesla coil. You will need a power supply to power it, anywhere from 12 volts to 60 volts and at least 3 amps. You will also need a power supply for the 555, seperate from the other power supply that is for driving the flyback, that is 12 volts and a few hundred milliamps or more. Take the flyback transformer out of the tv. Go over all the pins on the bottom of flyback with an ohmmeter and the lowest resistance between two pins will be the primary.

Carefully read this and make the circuit, which you can use a solderless breadboard or whatever you would like, or just wire it point to point: Well here is the basic schematic...

I used a smaller capacitor(you will have the find by experimenting) and for the pot and resistor between pin 7 and 2 i used a 2.2kohm resistor for maximum duty cycle. I hooked a 12 volt adapter up to pins 1 and 8 accordingly and i connected the flybacks power supply from the negative to the negative on the bread board(the one that the capacitor and pin 1 is connected to) and the positive to the primary on the flyback. The power supply for the flyback is a 50 volt transformer and a bridge rectifier with a 470 uf capacitor for filtering. You can use anywhere from 100uf to 500uf with the same results. This was all made on a breadboard for simplicity. I used a irfp460 mosfet and a 16ohm resistor from the gate to pin 3, but you can use any mosfet or transistor as long as the rated voltage is at least 4 times greater than power supply for flyback and must be mounted on an appropriate sized heatsink with an appropriate value resistor for limiting current from gate(or base for transistors) and they should be rated for 8 amps or more. Now just find the hv return pin on the flyback by bringing the high voltage wire near all of the pins. The one it arcs to readily is the hv return. Just be careful not to let it arc to the primary pins cause it will destroy the transistor and maybe the 555. I used two 6.8nf capacitors in parallel.

After you are done with that, make the high voltage capacitor using some aluminum foil, wire, tape and transparencies. This is how to make them:

Now make the secondary. Take the fan out of the microwave oven and take the spool off of the metal 'core' and cut the wire where it begins on the winding so that you can pull the wire out. Now take a secondary form ( a piece of pvc pipe or a toilet paper roll or paper towel roll) and tape the wire to the very end of the form. Now just start to wind until you either run out of room, or run out of wire. Make sure it is tightly wound and does not overlap or you will have to start all over again. If you want the secondary to last longer (or last at all at higher powers) put a few coatings of some kind of varnish.

Now make the primary. Use thick wire or copper pipe, for lower resistance and higher current carrying ability. If the wire is insulated you need to strip it every few inches or so, so you can tune it later. Now you can begin winding the primary. The wire should be at least 1 inch away from the previous turn. It should consist of 10-15 or maybe even more turns. The inside diameter should be big enough to fit the secondary in the middle of it with enough room so that sparks will not develop from the primary to the secondary.

Now you can make the spark gap. This might consist of two 'L' brackets and some steel screws and nuts, in such a way that it can be adjusted to the best gap distance for your tesla coil. For best performance, you can get a fan of some type and set it up so that it will blow directly onto the spark gap for better 'quenching'. Two other alternatives would be using a vacuum or making a 'sucker gap' where you use a vacuum cleaner motor to quench. Later, once you get this thing working you can make a rotary spark gap. Just read up on the internet to learn how.

Make a second spark gap called a 'safety gap' to insure that there are no destructive high voltages that get into the flyback and destroy that windings. Make this the same way, but it is not necessary for it to be quenched or anything like that. Just an 'l' bracket and some screws will be as affective as anything else. Run the flyback while connected to the safety gap and adjust the gap until it almost fires but doesn't quite.

Now you are ready to put the components together. Connect the safety gap across the high voltage and hv return (common) pin as well as the capacitor. Now connect one side of the capacitor to the spark gap and the other side of the capacitor to the inside end of the primary. Connect the unused side of the spark gap to an alligator clip and connect it to somewhere on the primary. Set the secondary coil into the middle of the primary and connect the bottom of the secondary to a length of wire leading to a metal rod or large nail pounded into the ground. This is your complete circuit. Now you are ready to give it a try!

Turn both of the power supplies on for the flyback driver. You should hear the spark gap roaring loudly and if you bring a grounded wire or a piece of metal near the top of the secondary, you should get a blue arc. If this is the case you are ready to 'tune'. To tune you just experiment with adding capacitors and taking them away, adjusting the alligator clip on the primary to different points, and adjust the spark gap for the best spark while maintaining a constant firing speed. Also, you can make a 'topload' for added capacitance on the secondary. I made a simple one by putting aluminum foil all around a ball and pressing down along the entire ball, ensuring smoothness. If you do make one you will need to retune by adjusting the tapping point, or alligator clip. if you want one long streamer instead of many smaller ones, make a 'breakout point' py placing a sharp piece of metal on the topload. I just tapped a sharpened nail on the topload with some aluminum tape.

After you have experimented with everything and got the best results, you can box it up now (which of course is optional.)

flannelhead

Mon Jul 07 2008, 08:14AM

Registered Member #952 Joined: Mon Aug 13 2007, 11:07AM
Location: Finland
Posts: 388

Hmm, nice tutorial!

You (or someone) should make a coil by following your instructions and take some pics of different building stages. Then it would be ready for the HvWiki. I believe it would be a great addition to the wiki!

Arcstarter

Mon Jul 07 2008, 04:57PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Dr. 2N3055 wrote ...

Hmm, nice tutorial!

Great! I am glad you think so! Anyway, i suppose i will make mine again and take some pictures. It is the simplest way i have ever made 5 inch sparks ;).

Arcstarter

Thu Jul 17 2008, 02:54AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

I made a cruddy schematic, but i need to find out how to download it first. I am going to put the tesla coil together like the instruction but that will be later.

Dr. SSTC

Sat Jul 26 2008, 08:46AM

Registered Member #1407 Joined: Fri Mar 21 2008, 07:09AM
Location:
Posts: 222

lol this was bascicly my first tesla coil

i built it a while back

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob