Latest verion of flyback transformer driver

It doesn't look pretty but it should work OK.

The first circuit board contains a voltage pre-regulator which cuts down 38V (3 x car batteries) to 24V on one rail and passes the 38V through on the other rail.

On the second circuit board the 24V rail passes into my LM317 high current voltage regulator, through a salvaged 'heavy duty' rectifier diode with a heat sink. This voltage regulator outputs just over 13V to power the 555 and mosfet gate driver.
I have used a 8 pin IC socket where the 555 timing capacitor would normally go so that I can easily interchange different timing capacitors.

There is also my diagnostic LED. The outputs of both the 555 and mosfet gate driver are soldered to a lead with one of those small two pin socket things at the end - I have many of these from old tv circuit boards. The input of my diagnostic LED, the mosfet gate driver input and the mosfet gate have the female part of those 2 pin sockets. So I can easily change things around and determine any failures.

The 38V rail passes through a 1.0 - 4.7 ohm resistor, which I will be able to submerge under water if necessary, and a 13A fuse.

The last circuit board contains the mosfet itself on a large heat sink with a 12V fan from an old PC power supply and the my snubber array - that is the 9 x 5W series resistors, some of which you can see at the end.

I have used 3 x 250V capacitors in series such that they add up to 68nF with a collective voltage rating of 750V.

Have so far tested the oscillation at my mosfet gate driver IC output and it is all good. Will need to check for oscillation at the mosfet with light globe of some sort next. Perhaps 38V might be just enough to get an ordinary light globe to glow red - I can't use the automtive light globe, as I have been, in this case.

Looks better than some of my projects.

Scavenging tv sets is a great way to acquire a bunch of parts.

Several sets of jumper clips (short and long) are one of the best things I ever got.

I guess that's the spark coil at the right.

I'm still wondering about the length of the waveform you are applying to it, and the frequency.

Old fashioned automotive ignition systems had 'points' inside the distributor. The points were opened and closed by a mechanical cam (6 or 8 sided). There was an optimum amount of time they were supposed to be closed, in order to conduct ample juice to the coil.

The purpose is to create a strong spark in the cylinder. So there was a meter called a dwell meter, to make sure the points were closed for a certain number of degrees of distributor rotation, per cylinder. Usually it was 40 to 45 degrees. The engine revolved twice per one revolution of the distributor cam.

The system is designed to deliver a high voltage spike at the secondary. Same as you're trying to get. But it is important to minimize heat buildup in the primary power loop. I once removed a spark plug wire to check the timing, then forgot to put it back on the plug. The spark could not be delivered to #1 cylinder. I drove the car and after five minutes the ignition module burned up. Stopped the car dead.

To make a Jacob's ladder, I believe the goal is to achieve a close duplicate of the automotive ignition system. Make sure the current is high enough, the dwell is long enough, the frequency is right, keep the spark gap small, etc.

There is also such a thing as 'souped up' ignition systems. It's supposed to provide a stronger spark. Might be worth a look at how they work too.

BradtheRad said:

Looks better than some of my projects.

Scavenging tv sets is a great way to acquire a bunch of parts.

Several sets of jumper clips (short and long) are one of the best things I ever got.

I guess that's the spark coil at the right.

I'm still wondering about the length of the waveform you are applying to it, and the frequency.

Old fashioned automotive ignition systems had 'points' inside the distributor. The points were opened and closed by a mechanical cam (6 or 8 sided). There was an optimum amount of time they were supposed to be closed, in order to conduct ample juice to the coil.

The purpose is to create a strong spark in the cylinder. So there was a meter called a dwell meter, to make sure the points were closed for a certain number of degrees of distributor rotation, per cylinder. Usually it was 40 to 45 degrees. The engine revolved twice per one revolution of the distributor cam.

The system is designed to deliver a high voltage spike at the secondary. Same as you're trying to get. But it is important to minimize heat buildup in the primary power loop. I once removed a spark plug wire to check the timing, then forgot to put it back on the plug. The spark could not be delivered to #1 cylinder. I drove the car and after five minutes the ignition module burned up. Stopped the car dead.

To make a Jacob's ladder, I believe the goal is to achieve a close duplicate of the automotive ignition system. Make sure the current is high enough, the dwell is long enough, the frequency is right, keep the spark gap small, etc.

There is also such a thing as 'souped up' ignition systems. It's supposed to provide a stronger spark. Might be worth a look at how they work too.

Click to expand...

This coil works well at about 20kHz and outputs roughly 20kV. When you use it as a jacobs ladder it produces a climbing plasma flame rather than a climbing streamer.

boylesg said:

This coil works well at about 20kHz and outputs roughly 20kV. When you use it as a jacobs ladder it produces a climbing plasma flame rather than a climbing streamer.

Click to expand...

Hey, great! I wasn't aware you got it working.

This is the kind of project that has 'wow' factor.

If you watch any 'mad scientist' movie, you'll spot a jacob's ladder snapping in a dark area of his laboratory.

It instantly tells the audience that the scientist has the ability to explore a realm of knowledge 'beyond the ordinary'.

BradtheRad said:

Hey, great! I wasn't aware you got it working.

This is the kind of project that has 'wow' factor.

If you watch any 'mad scientist' movie, you'll spot a jacob's ladder snapping in a dark area of his laboratory.

It instantly tells the audience that the scientist has the ability to explore a realm of knowledge 'beyond the ordinary'.

Click to expand...

I am yet to fully test this one. I have only verfied that the driver circuit oscillates as expected and that my fan (for the mosfet heat sink) works. But I have driven this same flyback transformer with a similar circuit at the same frequency and 24V in. This version of the circuit will be 36V in to the flyback transformer.