Intro: ZVS High Voltage Power Supply
Everybody has seen a high voltage arc somewhere, whether it be in the movies, on YouTube, or on TV. I think we can all agree that they are really cool, right? Well, what if I told you that you could build a power supply that would be able to produce these high voltage arcs? It would be extremely cheap and easy to build, use lots of recycled components, produce high voltage at a relatively high current, and be extremely versatile. Well, you can. If you follow the instructions contained in this instructable, then you should be able to have an awesome high voltage supply that you can use for any projects requiring high voltage, like Tesla coils, or just for fun! The video below will give a demonstration of this power supply in action and a detailed and in depth explanation on how the circuit functions. It will also complement the instructions in this instructable to make sure that you are able to learn everything about how a ZVS high voltage power supply works and how to build one.
Lets Get Started!
Step 1: What Is a ZVS Flyback Driver and How It Works
Many of you who are reading this may be asking "What is a ZVS driver"? Well, it is an extremely efficient oscillator circuit that is able to drive almost any transformer with a high frequency, high amperage electric current. It is the backbone of the high voltage power supply that this instructable is showing you how to make.
To understand how this power supply works, I will explain the different sections of it. The first section is the 40 volt DC power supply. This provides the 40 volts 10 amps that powers the ZVS driver board. It first uses a streetlight transformer to step down the 110 volt mains current to 40 volts. This is then rectified and filtered to achieve a clean DC voltage that is fed to the ZVS oscillator board.
The ZVS oscillator pushes and pulls current though a center-tapped coil around the ferrite core of a TV's flyback transformer. This constant changing of the current's direction creates a fluctuating magnetic field in the ferrite. This induces a current into the thousands of windings in the secondary coil of the transformer. Because there is a high ratio of secondary windings to primary windings, the voltage on the output of the flyback transformer is extremely high.
The ZVS oscillator is the most complex part of this circuit, so I am going to explain how it works. First of all, when the current is switched on, it flows though the inductive choke into the center tap of the transformer. The choke is to make sure the circuit does not draw to much amperage on start up. The current also flows thought the two 470 ohm resistors into the gates of the two Mosfets. Now, because no component is perfect, one Mosfet is going to turn on first. When this happens, it hogs all the gate current from the other Mosfet. It will also draw the drain of that Mosfet that is on to ground. This will not only let current flow though one half of the primary coil to ground, but it will also let current flow though one of the fast diodes form the other gate of the other Mosfet, locking it off. Because there is a capacitor in parallel with the coil, it creates a resonant tank circuit. Because of this resonant action, the drain of the other Mosfet will swing back and forth in its voltage, eventually reaching 0 volts. Once this voltage is reached, the gate charge from the Mosfet that is on will discharge though the fast diode into the drain of the opposite Mosfet, effectivly shutting it off. With this Mosfet off, the other Mosfet has the opportunity to turn on. After this, the cycle repeats thousands of times per second. The 10K resistor is meant to deplete any excess gate charge on the Mosfet, because it is like a capacitor, and the Zener diode is meant to keep the gates of the mosfets at 12 volts or under so they do not explode.
Now, this explanation may have been a little hard to understand, but do not worry! I also explained this with visuals in my video in the introduction, it is also here:
Step 2: Gathering Parts
To build this power supply, you will need a few parts, luckily, most can be salvaged for free. If you have ever seen an old CRT TV laying on the side of the road, pick it up, because it has most of the parts needed for this project in it. Ok, so you will need:
- Flyback transformer (Old TV)
- 2x 470ohm resistors (Old TV)
- 2x fast diodes (Old TV)
- 2x 12 volt Zener diodes (Old TV)
- 2x 10K resistors (Old TV)
- 2x N-Channel Mosfets (I got mine on bulk online, but you can also find them in an old TV or computer power supply)
- 0.68uF capacitor (Old TV)
- Wire (Old TV)
- Inductive choke (Computer Power Supply)
- Heat Sync (Old Computer)
- Power Transformer (Needs a high current output between 12 and 40 volts, mine is 40 volts and came out of a junk pile of streetlight parts)
- power plug
- Copper Clad board
Step 3: Tools
You will need:
- A soldering Iron
- Circuit Board Etching materials
- Wire cutters/strippers
- Hot glue gun
Step 4: Creating the Circuit Board
The circuit board of your ZVS power supply will hold all the components of the oscillator. Now, you can just connect all the components of your oscillator together on a solderable perfboard, or using plain old point to point soldering, but I preferred to make mine on a custom circuit board. Now to do this, you will first need to design your circuit on a copper clad board with permanent marker. This is relatively hard and takes some practice to do. Basically, you place the components on the board where you think they will fit best, then draw traces connecting the different pins of the components together in the most efficient way possible. You will need to closely follow the schematic diagram for this. Now, to actually etch these circuit boards, I suggest that you read some of my other instructables on how to do this.
Here is one on how to make a ferric chloride agitator:
And here is my 3 part instructable series on how to etch circuit boards:
Step 5: Soldering the Circuit Board
After you have etched the circuit board, you will need to solder components onto it. To do this, you will need to first use your soldering iron and solder to make sure that every trace on the circuit board has a thick layer of solder on it. After that, use your soldering iron to heat up the solder on the board and insert the components into the molten solder traces. After this is done, you should have a piece of circuit board that has all the components on it and all the connections are soldered together and connected correctly. You will also need to put screw lugs on the board to connect the external wires to. Wait to add the capacitors to the circuit, that will be in a later step. The circuit board will then need to be mounted to a heat sync. This will dissipate any heat that the mosfets produce. They will not produce very much heat, because this circuit is switching at zero volts (ZeroVoltageSwitching), but add a heat sync just in case. I added my heat sync by drilling holes in the aluminium and using screws to mount the Mosfets to the aluminium.
Now, I understand that not everybody has the capabilities to etch their own circuit boards, so if you want, you can just follow the schematic to build the same circuit on a cheap solder-able perfboard.
Step 6: The Capacitor Bank
In this circuit, the capacitors get very hot. This is due to them always having current flowing thought them. Now, the capacitor value we need to make this circuit work properly is 0.68uF, so we will need the most amount of capacitors together to reach this same value, but have a larger surface area for heat dissipation. You also need to get the voltage rating of them above 400 volts due to inductive voltage spikes in the resonant circuit. What I did, is put two capacitors in parallel, then added that capacitor in series with another capacitor to form the right value for this circuit. This whole capacitor was added in parallel to the primary coil of the flyback transformer.
Step 7: The Low Voltage Power Supply
The ZVS oscillator needs a low voltage power supply to power it. It needs about 40 volts at 10 amps to work at full capacity. To build this power supply, you will need to first take a light switch, and hook it up in series with a plug that goes to line voltage. This will then need to be connected to a transformer that can handle this type of load. I used a street light transformer, but a microwave oven transformer could be easily rewound to give the same results. The out puts of this transformer will need to be rectified. Because the rectifier is handling about 400 watts, it will also be mounted to the heat sync. To filter the DC, add a few capacitors in line with the power rails on your ZVS driver board.
Step 8: The Flyback Transformer
This is the part of the power supply that converts the AC signal produced by the oscillator into a high voltage current. A flyback is usually used in an old TV to provide the accelerating potential for the anode. Now, to couple the transformer to the oscillator, you will need to wind 10 turns of thick gauge wire around the ferrite core sticking out of the side. You will then need to connect the wires to the ZVS oscillator circuit, with the center tap going to the inductive choke and both sides going the drains of each of the MOSFETS.
Now, one issue with a flyback transformer at high voltages is arc over on the bottom pins. To solve this, you will first need to find the high voltage pin on the bottom. You can find this by turning it on and seeing what pin the red wire will arc to. Then, solder some wire to this pin, and cut off all the other pins. You will then need to cover them in melted wax to prevent arc over.
Step 9: Mounting the Components
The most important part of a power supply is the case. I made my case using 4 pieces of oak planks all screwed together. All the components were then mounted to the top using wood screws and hot glue. I kept the top uncovered because it looks cool, but you can build this part of the high voltage power supply however you want.
Step 10: It Works!
Now, after everything is built on your ZVS driver, it is time to fire it up. To do this, you will first need to connect the ground of the flyback transformer (The wire sticking out of the transformer bottom) to a heat sync on an electrically insulated surface. Then, connect the anode of the transformer (The red wire with a suction cup) to a chicken stick. This is a term used to identify an insulating pole that you can hold one end of to move a high voltage wire without getting shocked by it. I made my chicken stick with a PVC pipe, some alligator clips, and a metal stick, but you can also use a well insulated screwdriver. With that, have fun with the arcs!!!!! Check out the next step for other things you can do with this supply.
DISCLAIMER: This project utilizes high voltages at high currents. The output of this power supply IS LETHAL. I highly advise anyone that builds this to exercise caution when using this power supply. Use common sense when operating and do not under any circumstances touch any of the terminals of the flyback while operational. I am not responsible for any harm caused due to the creation of this ZVS power supply.
Step 11: Other Uses
This power supply is extremely versatile. I have used it in a great many of my projects, from a Tesla coil, to a method of carving pumpkins. I will put links to my other videos below that explain the many ways to use this power supply.
Make sure to vote for me in the Power Supply Contest!
Thanks for reading and good luck building!
DESTROYING WITH HIGH VOLTAGE:
EXTREME PUMPKIN CARVING