PLEASE READ: The above schematic is a non-varrible version of the dual flyback ZVS. For best results use no more then 40vdc and large wires. Since the 2nd flyback acts very much like the resonent capacitor-- you can remove it and see if that works better. To start the circuit after it has been removed however you will need to place a 1000pf or so 2kv capacitor between one gate and the center tap of the primary. Otherwise the supply will not begin to oscilate. In this mode, operation above about 30volts will be difficult but at lower dc drive voltages the flybacks will produce higher outputs. The new schematic also replaces the zeners with a 5w 16v zener diodes (2N5353 etc). I hope you find this helpful. Build with short leads and place fly-backs separate from supply using large leads to connect the unit. Putting both fly-backs in mineral oil is a very good idea and will keep unwanted arcing. Use 8mm ignition wire for best results on the HV side. Keep output minimal, trying to push fly-backs to huge arcs and large ones is usually a death sentence for them. If you want fat arcs try winding your own or getting a larger type of transformer, the diodes and internal wire just cannot handle currents as high as many circuits show for long. Ignition coils are better at this.
I have been working on this for a while-- A a variable high current power supply. This is one of the prototype units working with mosfet drive systems and PWM options. See what happened when I hooked it up two ignition coils! Bipolar wired in series at over 70volts! The CD-707 is able to do this, but I need to save enough to get some new ignition coils first--these died after the voltage no longer was dissipated on the arc shown--they arced internally and were damaged. This was only because I moved them further apart. I got 100kv or more--but too far apart they arced inside. I cut one open to find out what happened and figured out some interesting things. If built you want to step up the power and make sure all is used in the arc so that it does not break the insulation internally. Ignition coils generally do not produce more then 20kv at lower current. With this driver, they are producing over 50kv each. It's not 500ma, probably close to 100ma however.
MY HOME MADE HIGH CURRENT AND HIGH VOLTAGE LAB SUPPLY=
I went on to design and build the CD-707 (BELOW). My latest power supply for the mad-scientist lab :) lol. The unit is both a ZVS and a circuit I call the SPSv. A modified version of the push-pull ZVS that operates at higher frequency and also is far more flexible and in some uses power efficient. A 3rd mosfet makes it adjustable from 20-110kv with x2 good color TV flybacks. The current is impressive. I built the system onto two PC boards and into two metal boxes bolted together. The same high-current DC supply gives a 1200W PWM and a 400W+ ZVS/SPSv. This allows me to drive an impressive number of coils and high voltage transformers or other devices. Like the CD-1628 and the CD-303 in one unit, the CD-707 is my best yet. It is solidly built and I designed the over-current protection (shuts off supply if too much power pulled or part fails) as well as a 2 stage power on system timer for operation on both types of supplies. A remote control button is the isolated switch that turns on the system. First at only about 1/3rd power--then goes to full. When button off-- It steps back down to 1/3rd just before turning off entirely. Cooling and all control functions stay on, this is just mosfet power control for output to transformers. This type of circuit prevents damage to parts and accidents. In such high amp systems (as much as 8-10amps at 20-70volts here) the remote and power control had to be built carefully. This flexible driver has replaceable components and upgrade features as well as an audio input option for singing arcs on both the ZVS and PWM systems. PWM and ZVS outputs are in the back, remote and Audio input as well for 'singing arc' soon to be. --G.Beasley KF7DFP
ELECTRONIC LEVITATION with the DC 100kv supply box set to about 90kv. Watch entire video to see full power output of the CD-707 using 2 separate transformer systems! Resonant caps are fully built in and switchable, PWM has X3 separate bandwidths of operation for variable frequency with expansion possible. This HV supply can provide far better performance then units I have seen on line. It took a while, but I came up with good board layouts as well as the stuff I needed. The system is a great addition to my high voltage testing and is more then powerful enough to drive a medium sized solid state Tesla coil. (SSTC). Also the SPCv function from the ZVS circuit is soon to be complete. Basically no res-cap is used and the mosfets are controlled with a 3rd mosfet to produce a fully variable supply. A single 2 flyback transformer box with oil is all that is needed to produce 20-120kv or so. This makes it very useful. The new ZVS I designed mainly for 2 flyback systems (TV flybacks) is able to power other things as well and can be far more efficient as it respects the true AC created between drains. Higher voltage can be produced with flybacks at less current but still very useful. This is a complex topic for later. Email me for questions. And still pictures are coming as well as more videos including a MOT experiment. --G.Beasley KF7DFP