Flyback Transformer Tesla Coil




Introduction: Flyback Transformer Tesla Coil

There are not many (any that i found) instructions to make a flyback powered tesla coil. so i decided to make one.
(note first time making an instructable)

Not my picture :P but if you use a computer power supply (building mine now will update when done.) you may get arcs about that size

I will also be updating this as i upgrade it. and as a change things. i may add a page at the end for how to audio modulate it once i finish that. it should be as simple as an audio input to pin 5 of the 555 and the other audio to ground.

Update 7/9/14: i was so excited that i finished that i connected my computer psu to it and somehow my 555 blew.... no idea the only connection was a common ground. this post will not be updated until i troubleshoot the circuit or until i upgrade to a ZVS driver. (i will make a 2nd section for the ZVS and keep this one for all those people just starting and still use radio shack :P)

If you are reading this i assume that you know a few things:
#1 high voltage safety!!!
#2 how to make and use a 555 timer circuit (if not look it up :D )
#3 high voltage safety!!!

#4 how to read a schematic.

#5 need i say it again? if so read steps 1 and 3.
#6 i cannot believe i forgot this one when i first published it.... wait for it.... Duck Tape!

and have a few parts:
2X 555 timer (good to have a spare)
1X 2n3055 (or similar) i have not blown one yet!
2X potentiometers can be 50 or 100 use whatever you have. i think i am using a 100k and a 10k normal resistor.
ceramic cap of less than 1uf but greater than 0.01uf

root (beer) bottle
aluminum foil

wire: bread-boarding wire, thin magnet wire (LOTS about 1/2 a roll of the real thin stuff from radio shack) and solid core thicker wire for primary (can be a little smaller than house wire)

How it works:
The 555 timer sends a square wave to the 2n3055 that turns the power on and off to the flyback. the flyback steps it up to about 10,000 volts (this WILL hurt do not be dumb) and charge a capacitor up. when the capacitor is charged it jumps the spark gap flooding all that power from the capacitor into the tesla coil primary.

I get about 1cm-2cm streamers all the time (i will get better once i get my coil a good solid ground) and get about 1-1.5 inch arcs to a screwdriver. (is not grounded) It will light CFL's at about 1' but the really small bar ones work best.

Step 1: Flyback Driver:

I will not explain it nearly as well as Techno guy

so for now follow his :P one thing i NEED to add is that some 555 timers will fry at 12v (i was cheap :P) so i would power the timer circuit off of 4 AA's. so have the + of the timer go to the + of the AA pack. the + of the transistor (2n3055) go to the 12V+ and BOTH MUST have a common ground.

Edit:7/6/14: 2 transistors in parallel give a very very slight improvement in power (CFL light up a VERY tiny bit brighter)

Question: Why does it give the same power using a 30V 1A supply as a 13.5V 3/4A supply?

Step 2: Output of Flyback/tesla Coil Driver

A note before i begin: I have read that the capacitor and spark gap can swap places with each other and that one was is better than the other. but i forgot what one so i did this as it made more sense to me at the time.

The capacitor is a bottle wrapped in aluminum foil and full of very salty water. if i am correct you want to have the water level above the top of the aluminum foil to prevent corona discharge. you can add more capacitors in parallel for better performance. i prefer to use 2 because then if i bump the Tesla top load it is no so painful and the spark gap not so loud

Step 3: Coils

My primary is 4 turns of near-house gauge thickness taped to a plastic lid. do not use stranded wire. mine is really old cotton/wax encased wire and can arc to itself so use rubber. you can use bare copper for the primary and an alligator clip to tune it. i tried winding mine around the primary but a pancake seems to get better performance.

my secondary is 650-700 turns really thin wire around a 1/2" or 3/4" PVC pipe about 1' long. took me about 30 min to wind.
(and to all your coilers out there: i took my time and never crossed a wire)

I don't use a top load because i can't see any streamers off it. i prefer just a wire so i get 1-2cm (about this: ---- on my monitor) but on a coil this small all you would have to do is wrap foil around a ball.

Question for readers: anyone know of a simple flyback SSTC i can build? i don't care about power (to a degree i wan small streamers :P)

1 Person Made This Project!


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6 years ago

I recommend the ZVS driver here I power it with a variable transformer I got on amazon for like $50, then run it through a full bridge rectifier to get DC voltage. Most parts I got from scavenging CRT TV boards, the rest online. I use IRFP250n MOSFETs. I've had this badass up to 65v with no heat issues or burnouts, only problems are the flyback arcing to itself or the voltage getting so high it arcs right through wire jackets, give it a shot!


7 years ago

I don't believe you can drive a tc with a flyback alone, not enough power.
If you want a really simple SSTC (single transistor) here are 2 that I like to play with...

The signal in the 1st pic represents a 555 interrupter circuit, I just placed a random value in there.. BJT is a medium to high power npn (tip31 or 3055t or others), Zener is 15v, Diode is an ultrafast recovery ( >= UF3004).

Try to supply only about 1/2 the mosfet rated voltage to leave some head room for resonant rise..

Mosfet should be 400v+ with a min 10A rating.


Reply 7 years ago

Old project from when i had first started electronics. yes it did "work" but i really only got 1/4" streamers with a Spark gap. i re-built it later using a two mosfet oscillator running at about 50v into a hand wound transformer and then into the tesla coil with a spark gap and got a bit better. haven't touched high voltage in a long time (above 600v). building a tube SSB transmitter and a 220W audio amp.


Reply 7 years ago

re-read this and it is pitiful how many errors I made, both text and electrical. no
the 555 timers survived 12v I never tested the conventional power
supply that I had used. It gives 19v nominal and at >250ma draw drops to about 12v. (also very messy now that I have a scope)
Someday I need to put some real projects up and remove this one.