This Page came from http://4hv.org/schematics/info.cgi?entry=usfd Ultra Simple Flyback Driver  uses  a halogen lamp switchmode supply. Description If you want high voltage without the hassle of soldering, and without the agony of making a trip to Radio Shack, this is the circuit for you. Two components, little to no soldering, and you're on your way! This has to be the simplest flyback driver I have ever seen. Warning Don't even think of touching the output. If you do, at the very least, you will be badly burned and shocked. You may lose digits, extremities, or even your life if you're not careful. Remember to be safe. At these frequencies, capacitive discharge is a major problem. Ungrounded objects, such as yourself, will still attract arcs! Skin effect will protect you somewhat, but the burn risk is still quite severe. Don't rely on an insulator to protect you: just stay away from the circuit while it's in operation. Should you attach a capacitor of any sort to the output of this circuit, electrocution becomes a very real threat. I don't recommend that any beginner attempt to modify this circuit without a full grasp of the principles of high voltage safety. Remember that most cylindrical flybacks include a capacitor as part of the voltage multiplier. This means it is capable of lethal currents! Always ensure that a flyback is fully discharged before handling. Parts List Flyback Transformer: Any type of flyback you can scavenge, buy, or "borrow" should work just fine. Most cylindrical flybacks output DC, and most flybacks with disk-shaped secondaries will output AC. SMPSU: Switch Mode Power Supply Unit. These are used for low-voltage lighting. Generally, they're small boxes with lots of interesting components inside. You want to stay away from the heavier, larger units; they're just transformers. The SMPSU outputs a high frequency, low voltage current that just happens to be perfect for driving a flyback. A picture of the SMPSU used in this demonstration. Note its size and configuration. The label from this SMPSU. An internal view of the SMPSU. Other: You'll need some electrical tape, a multimeter that can measure resistance (optional), and a length of insulated hookup or high voltage wire. Steps First, you'll want to take a good, hard look at your flyback with a multimeter. Try to locate two pins on the bottom with low resistance between them. This will be a primary winding that you can use to drive the flyback. If you can't find a primary winding, don't panic. It's probably better to wind your own. Just wrap 10 turns of wire around the core of the flyback, and hold it securely in place with tape. You should end up with something looking approximately like this: If you experience any problems with intermittent output, you may need to add a few turns to your primary. If there's not enough inductive reactance on your primary, you may be triggering the protection circuit. Now comes the hard part. :) Take the two wires from step one, and connect them to the two screw terminals on the SMPSU. At this point, you should have something like this: Now all you have to do is locate your high voltage return pin. Simply turn the unit on, and very carefully bring the high voltage output wire down to the pins on the bottom of the flyback. The pin that it arcs to like mad is the pin you're looking for. You'll want to attach a length of wire to that pin in order to keep it from melting into nothing. The completed flyback, ready to arc. The flyback in operation. Listen to the arc. [mp3 format, 36KB] You're all set! You can plug it in, turn it on, and watch it go. Conclusion This circuit outputs a very hot, very powerful arc. It can melt wire in a matter of moments. Observe: A very hot arc, in the process of melting the output wires. The result. Notice the red-hot blob of molten metal hanging from the top wire. The obvious implication here is that for extended use, or use with plasma globes, some current limiting is going to be necessary. Look into a high-voltage resistor; it will extend the life of your flyback, and it may just extend your life as well! Credit This whole project was built and designed by ma77. Any praise, gratitude, etc, should be directed towards him. Any hate mail, problems, questions, etc, should be directed to me. A big thanks to ma77 for a great project, and a big contribution. Last updated by Chris Russell on June 19, 2002.