Picture of How To Make A High Voltage Power Supply
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!

Picture of 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.

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rohan paul3 months ago

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

tommarr653 months ago


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

UmarM16 months ago

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?

UmarM16 months ago

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?

R.A.T.M3 years ago
respect on the Ramminstine
liddleLOL3 years ago
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?
rocketman221 (author)  liddleLOL3 years ago

Non polarized caps will work. They are larger than polarized caps though. With them it doesn't matter which direction you hook them up.
XOIIO4 years ago
Have you found a different source of charger boards yet?
rocketman221 (author)  XOIIO4 years ago
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.
Thats pretty sweet, any estimate to when you think you might have an instructable?
rocketman221 (author)  XOIIO4 years ago
The new charger is still just a rats nest of wire on my breadboard, but I will update this instructable soon.
Can you post a schematic if you can so we can still build it without the board? Thanks.
rocketman221 (author)  brooklynlord5 years ago
Here is the schematic. The number of turns on the transformer is just an estimate. 
Inverter Power Supply.png
rocketman221 (author)  brooklynlord5 years ago
I can put together a schematic, but I don't know how many turns the inverter transformer has.  
Fangofwar5 years ago
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.
rocketman221 (author)  Fangofwar5 years ago
More caps are fine, but you will want to use heavier wire for the output. 
Thank you sir! i will keep this in mind.
wjbombo5 years ago

The charging boards are not available or the link is incorrect.  Do you have a part # for the charging boards or a suggested replacement for this part if the ones you suggest are unavailable?

Thank you.


rocketman221 (author)  wjbombo5 years ago
The chargers are sold out. I don't know about a replacement for them though.
I am working on a better power supply that doesn't use them, but I've got a lot to do before I can make the instructable. 
h8redflip5 years ago
Hi, do you have a new link to a charger board, as that one has expired, or any specifics to look out for? thanx :)
rocketman221 (author)  h8redflip5 years ago
It looks like they are sold out. Hopefully they will get more. 
panzuman5 years ago
probably a dumb question but what about microwave caps? i have a ton from my tesla coils that i build but could i use those?
rocketman221 (author)  panzuman5 years ago
Microwave caps would work, but they are a lot higher voltage and lower capacitance. The charger board can't charge them to their full voltage.  
science kid5 years ago

thanks alot.

Riojelon5 years ago
Can I use this in ac?
rocketman221 (author)  Riojelon5 years ago
The power supply is dc only. 
sharlston5 years ago
how about making a welder out of it?
rocketman221 (author)  sharlston5 years ago
It will weld stuff together but its not very strong.
SimonTunes5 years ago
rocketman221 (author)  SimonTunes5 years ago
Yes but they might be harder to find.
Grrr electronics goldmine dosent ship to the UK!!!
wow dangerous stuff
ChuKoNu6 years ago
Cool Instructable! Roughly how long does it take to charge these capacitors?
rocketman221 (author)  ChuKoNu6 years ago
It takes about 20 seconds to charge to 350 volts with a 3.3 volt input. Thats with 9 charger boards and 2820µF capacitor bank. It is helpful to increase the input voltage to charge above 350 volts it can be run at 5 volts after the caps are charged above 300 volt.
where do you get a charger board?
They are from electronic goldmine the link is in step 2.
What are the max input and output voltages for these boards?
rocketman221 (author)  Sponzyparadox6 years ago
3.3v in gives about 400v out. 5v in gives about 600v out. 9v in gives about 775v out. 12v in gives over 1000v out. Anymore than 5v in overheats the boards really fast and the output current must be kept low. I wouldn't recommend running them at more than 9v.
How fast do they heat and woudfl it be hard to cool them?
rocketman221 (author)  Sponzyparadox6 years ago
How fast they heat up depends on the load. The transistor is what heats up. You might be able to replace it with a larger one, or make a heatsink out of some foil tape. I have never tried to run them at more than 5 volts with any load though. If you need a higher output voltage I would suggest using a voltage multiplier.
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