How to Make a High Voltage Power Supply




About: I enjoy building electronics & robots. I like building computers as well as writing programs & web sites. I like to build and launch rockets. I especially like to play with high voltage power suppli...

This power supply puts out 400 volts maximum and stores it in a capacitor bank. Mine is 2820 uF. You could use more or less capacitors.
I originally built this to power a small coil gun but it can be used for whatever you need it for.
It runs off 3.3 volts but it will run off of 2 "D" size batteries with a reduced voltage output and slower charge times. The parts can be purchased online for about $20.
I recommend running it off an old computer psu. The one I use to run it is rated to 16 Amps on the 3.3 volt line and it runs this fine.

For instructions to make the 3.3v power supply look Here


Step 1: Warning!

Warning this device can generate 400 Volts from a 3 volt input.
This energy is stored in capacitors and it will still have power in it even when unplugged.
It is capable of putting out several amps!The output can easily be deadly!


You are responsible for anything you do with this.

You should make certain that the device is clearly marked

Here is the warning for this device
High Voltage Warning Sign - for gimp
High Voltage Warning Sign - for photoshop

Here is the font I used on the warning signs above.

Step 2: Parts & Tools

The Parts Needed
Charging Boards
I used 8 Boards but order a few extra in case you mess up on one.
Charger Boards - Electronic Goldmine
Unfortunately Electronic Goldmine is sold out of the charger boards. I don't know if they will get them back.
However I have been working on a bigger and better power supply, it won't be done for a while though.

Capacitors these should be rated to 400 Volts minimum and a total of 2000 - 3000 uF.
Electronic Goldmine is currently out of the ones I used.
Capacitors - All Electronics
Capacitors - Ebay

Switches (2) 15 Amp minimum rating
Alligator Clips or Binding Posts for HV out (1 Pair)
Small wire for soldering to charging boards (22AWG Solid)
Heavy wire for power in & out (18 - 16AWG)

Tools Needed

  • Soldering Iron and solder
  • Hot Glue Gun and Glue Sticks
  • Wire Cutters
  • Wire Strippers
  • Nedle Nose Pliers
  • X-Acto Knife
  • DC Volt Meter (optional)

Step 3: Prepare the Charger Boards

The long black wire is the negative (-) input. The long red wire is the positive (+) input.
Hot glue around the base of those wires to prevent them from breaking off as you work with the board.

The blue, green, and yellow wires are not needed for this project so you can snip them off.
Connect the pads and HV out wires as shown in the pictures.

Make sure that any flux left over from soldering is removed from the boards. The HV will arc through the flux and it can catch the board on fire! It will typically arc on the narrow part of the board by the HV output wires.
I recommend cleaning the flux off with a toothbrush and alcohol.

After the board is dry it should be tested. To test it hook a voltmeter to the output and connect 3 volts from 2 AA batteries to the input.
Using the batteries will keep the current low so the board doesn't fry instantly if there is a problem.
The volt meter should read over 350 volts. If it arcs, you didnt get all of the flux off the board.
Once the board is connected to a 3.3 power supply it should put out over 400 volts.

Step 4: Prepare the Capacitors

Tightly wrap some wires around the leads on the capacitors, then solder. These connections must be made very well, if it is not done well and it arcs it will melt the leads and the wires.

Most all capacitors have a stripe on the side, this marks the negative (-) side.
Be sure you get the correct polarity on the capacitor

Step 5: Connect the Capacitors Together

Wire all of your capacitors together in parallel (+ to +, - to -) if you are putting it in an enclosure of some kind do this first, then wire them together.

Step 6: Connect the Charger Boards

Mount your charger boards in your enclosure with hot glue (If you are using an enclosure). Then connect your input lines in parallel. Now connect the HV output lines in parallel.

Connect the HV out lines to the lines on the capacitors then connect a piece of heavy wire to that connection.

Step 7: Mount Your Switches

Attach the power switches.
Connect the negative line from the power cable to the negative input on the charger boards.
Connect the positive line from the power cable to the two switches.
Connect the output from one of the switches to two of the charger boards positive input.
Connect the output from the other switch to the positive input on the rest of the charger boards.

Step 8: Finish It Up

Run the 3.3v power line out of the case and attach whatever connectors you need to connect to your power supply.

For the high voltage out you can either connect it to binding posts or you can run the wire out of the case and connect the alligator clips to it.

Make sure that this power supply has the proper warnings on it.

Other things you can do. I plan on doing these when I get the time and money.
  • Attach a panel volt meter to it
  • Attach a panel amp meter to the input
  • Connect it to an scr to control the discharge
  • Add a key switch so that it doesnt accidentally get turned on

Step 9: Using It

To use it turn on the switch with the 2 charger boards on it. when it reaches 50 volts turn on the second switch. then let it charge to desired voltage and turn off both switches.
Do Not Exceed 400 Volts
Do Not Discharge While The Switches Are On. This can overload and damage the charger boards.

I reccomend using a volt meter to watch your charge voltage.
I have posted the full sized pictures on my website here.

Here is my original video

Here is a newer video of my power supply discharging through various items.

Step 10: Update - New Flyback Charger

I have come up with a modified flyback transformer that will work with this power supply using spare parts from my junk box. This is based on the rewound flyback from here, and my driver circuit is a modified and much simpler version of this one.
I haven't gotten around to actually making a circuit board though. It is still sitting on my breadboard. I eventually plan on using this for a coil gun project, but that probably won't happen anytime soon.

The secondary is 300 turns of 28 awg wire. The primary is 15 turns of 22 awg wire.
The primary will need tweaking depending on the driver used and the input voltage.

The layers of the secondary are insulated with a couple layers of teflon thread tape. There are a few layers of electrical tape separating the primary from the secondary.
The core is from a flyback transformer I took from a 15" computer monitor.

The output will be AC, so it needs a diode in the line to rectify it. I have gotten by with a 1N4007, but a fast recovery diode like the UF4007 would be better because of the high frequency being used.

This can be driven with one of the many flyback driver circuits available. I used a simple 555 timer circuit to drive mine, but it would work better with a ZVS or Mazilli driver.
For more information on flybacks check out the HvWiki page on flybacks. There are also many good instructables on flybacks so I won't go into building a driver here.



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    104 Discussions


    2 years ago

    check this out ppl... look how does 3.5 MILLION VOLTS look like .... beautiful

    2 replies

    Reply 2 years ago

    They can write whatever voltage they want on the package, it doesn't make it true.

    That taser is only going to produce around 20-30KV. You would need a very large Tesla coil or Marx generator to produce 3.5MV.


    Reply 2 years ago

    I'm just saw what was written on the pack... Never went to test it...
    Sorry if the info is wrong

    rohan paul

    4 years ago on Step 6

    i think what u used here are flash camera circuits !!


    4 years ago on Introduction


    i run a small wheelie bin cleaning company and i am interested in setting up a trailer unit which powers the electric motor on the pressure washer with electricity instead of a loud petrol generator. I am also interested in getting it as a hot water system but most of these on the market require 3 phase 400 volts. Any help or suggestions would be gratefully received thx


    4 years ago on Introduction

    I want to generate 400 volt from 12 volt DC bettary? i have 400 rms transformer, which is giving 300 volt from 12 volt, but i need 400 volt. what should i do?


    4 years ago on Introduction

    I want to generate 400 volt from 12 volt DC bettary? i have 400 rms transformer, which is giving 300 volt from 12 volt, but i need 400 volt. what should i do?


    7 years ago on Introduction

    I need help:

    I am making a charging circuit for a coilgun, but i accidentally bought non polar caps. I was wondering if i could still use these with some sort of circuit adjustment, or if i need to purchase all new polarized caps? Can you help?

    1 reply

    Reply 7 years ago on Introduction

    Non polarized caps will work. They are larger than polarized caps though. With them it doesn't matter which direction you hook them up.


    Reply 7 years ago on Introduction

    I've come up with a circuit using a flyback transformer (from an old computer monitor) and a 555 timer that charges the caps significantly faster, but I'm still working out the bugs.
    My current version has a flyback with a 15 turn primary and a 400 turn secondary.
    I used 22awg on the primary and 28awg on the secondary.
    It charges to 380v in about 10 seconds with a 13.8v input (could use a zvs driver for more power).
    I need to get some high speed diodes to rectify the output. I have been using 1N4007's but they are too slow. I will get some UF4007's instead.


    Reply 7 years ago on Introduction

    Thats pretty sweet, any estimate to when you think you might have an instructable?


    Reply 7 years ago on Introduction

    The new charger is still just a rats nest of wire on my breadboard, but I will update this instructable soon.


    9 years ago on Step 4

    first off, thanks for providing me with a way to kill time this weekend. secondly how would using 10 of the capacitors you used affect the output? i plan on making a coil gun.

    2 replies