Introduction: Microwave Oven Transformer High Voltage Rig

Picture of Microwave Oven Transformer High Voltage Rig
For my first Instructable, I decided to make a high voltage power supply out of 2 microwaves. The videos should give you good idea of the final product (I'm using only one of the 2 transformers):

Step 1: Disclaimer

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This circuit gives off more than enough power to kill you. I am not responsible for any injuries you may get from doing the following steps.

Step 2: What You Need

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Most of the stuff you need will come straight out of a microwave, so see Plasmana's instructable, but you will need:
  • 2 Microwave transformers
  • 2 Safety switches
  • 2 125V 15A fuses and holders
  • 2 Grounded plugs
  • Random wires that you can get out of the microwaves
  • Something to mount the stuff onto (I used scrap 2x4)
  • At least 2 friends - one who knows CPR and one that can call 911 NEVER DO HIGH VOLTAGE EXPERIMENTS BY YOURSELF

Step 3: Mount Everything

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Simply place the parts in an orientation so that you can wire it up easily. Then drill the transformers and fuse holders onto the 2x4 and nail the safety switches down.

Step 4: Wire It Up

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The circuit will be wired in series, giving you an output of about 4kV. I decided to use 2 plugs to make sure I don't set the wires on fire :D. You can wire the rest up according to the schematic below, if you can't read it, you shouldn't be making this. To get out the most power, attach the 2 HV Out wires together and touch them to ground. Tip: before attempting to ground anything, scrape off enough varnish to have a good connection. Caution: This setup is un-ballasted, and the transformers can heat up very rapidly. Use this only for short periods of time.

Step 5: Power It Up!

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Carefully, wearing non grounded shoes, holding non-conductive rods to push the switch, press the switches and hold them. Don't look directly at the arc without eye protection, it is close to the brightness of a welder. You should now have a spectacular arc to show off to your friends and family!

Step 6: Random Notes

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  • I purposely put the 2 safety switches on opposite sides of the 2x4 to prevent me or anyone else from turning it on by themselves. Also, to keep the board from breaking under the ~12 lbs of transformer, I made it as short as possible.

Update as of 3/5/09:
  • I decided to ballast the first transformer with the second, schematic is attached

Step 7: Update: Neater and Safer

Picture of Update: Neater and Safer

I decided that I could find a better and more presentable base for my project than scrap 2x4, so I reorganized everything onto a piece of Formica giving me space for at least two more transformers. Also, it is more easily troubleshoot-able and modular


BdSquirrel (author)2016-04-30

This would make a good squirrel (or other pest) trap, provided you monitored it and only connected it to administer the pentaly.

This is also a good way to get someone killed. Even if the electricity doesn't cross your chest and stop your heart, touching any other part of your body will cause violent muscle contractions which could cause broken bones or other injuries. I won't even mention the serious buns and tissue damage it will cause!

Lol... "buns damage".
I know what you was just a funny thought.

"....I dunno, I went outside to play with my transformer and the buns just exploded! Well just do pizza."

-"Dude, what's wrong with your shorts!?"
-"Doc says I got wear this bandage for a month. I was playing with my transformer and caused serious injury to my buns".

einyaa (author)2016-02-29

Just be aware of that the current from a MOT (microwave oven transformer) can KILL YOU in an INSTANT ! Unlike the misunderstanding that the higher the voltage is, the more dangerous it is, it's the current flow (especially at 50 and 60Hz) which kills you. The frequency of 50-60Hz is also contribuing to an cardiac arrest (atrial fibrillation) of the heart. Tesla coils on the other hand, is not so dangerous at the HV-side because even if it is hundreds of kilovolts output, the current is very low. Also the frequency is very high, and will not pass through the body but only on the surface of the skin. It can burn yes, but will not pass the heart.

A typical MOT delivers 2000 volts or more output, and currents up to 500 mA. Ten times higher than the current necessarry to stop your heart.

Again - playing around with MOTs requires a deep understanding of the dangers it represent. Always have another person with you when experimenting with high voltage. He/she may disconnect power if an accident occurs.

tony54 (author)2014-04-20

Use an old NEON SIGN TRANSFORMER INSTEAD, MUCH SAFER ! Don't build this to play with, only if you are experienced with electricity and VERY COORDINATED. Your first mistake could be your LAST MISTAKE ! If you insist on trying this at least put SEVERAL RESISTORS IN SERIES TO LIMIT THE CURRENT IN CASE YOU DO COME IN CONTACT WITH THE HIGH VOLTAGE. Also, make sure to GROUND THE CASE (AND THE TRANSFORMER) TO EARTH GROUND. Microwave transformers use one of the HV leads connected to the transformer case which is EARTH ground in a microwave. Use many 10w or higher to total 300,000 ohms which limits the current to 5ma (1500v / 5ma = 300,000 ohms). It takes about 5ma to POSSIBLY stop your heart. Still not safe but a big improvement. Also, space out the resistors several inches, the HV will want to arc across them.

As for putting a light bulb in series with the primary, it's a good idea but use a LOWER WATTAGE BULB. A 100w bulb would be, 120v / 100w = 1.2 ohms. Not much resistance. A 5w or 15w bulb. 120/5w=24ohms 120 / 15w - 8 ohms

I would use the 5w myself, ONLY INCANDESCENT WILL WORK, Fluorescent or CFL will probably just burn up.

If you aren't EXTREMELY CAREFUL use a neon sign transformer, you can get MUCH HIGHER VOLTAGES much safer. Or a TESLA COIL.

P.S. The average microwave transformer can put out AT LEAST 1A, possibly 10A or more upon shorting. Wear sunglasses if you need to look at an arc or WELDING GLASSES if you weld. Unless you like using a cane instead of eyes.

69buickgs (author)tony542015-08-28

Yeah, and 5mA won't COOK your internals.

GarethT7 (author)69buickgs2016-02-26

No, but about 30mA can ! Under the right conditions and about 10mA can kill livestock.

To be honest, being a professional industrial electrician, I am amazed at what is going around this place.

Agenda 21 in full effect I guess ;-)

M2aestro (author)tony542015-07-14

Please don't depend on sunglasses to protect you from arcs. The one you generated could be too much for the attenuation of the wavelengths resulting from the arc. Possibly multiple layer filters, such as the semi-rigid film eye shields used by many senior outdoors, but worn over sunglasses would be safer? Also, please don't allow the arcs to be viewed by an audience that does not have adequate protection.

crazy-blender (author)2013-04-11

I believe you wired this wrong. to wire it correctly you must connect the cases together and ground it then arc between the 2 HV out wires. if you want more power you can wire 2 microwave oven transformers in series as a half-resonant circuit or better yet wire 2 in series in parallel with 2 more in series and connect them like this:

KrishenM (author)crazy-blender2016-01-13

Nice schematic. Shouldn't you have a ballast to keep it from over heating though? Although I think the ballast in step 6 of the main post is wired incorrectly. I think it should be in series with the output. No?

69buickgs (author)crazy-blender2015-08-28

My next step. Only have two for now though. Just have to do a little more searching. In going to start trolling the alleyways around the student housing areas at the local colleges for discarded microwaves.

Ignore the PFC capacitor you don't need it to work. The ground connection is in the middle. As I said before connect the cases of the transformers together and ground them. draw arcs between the 2 HV outputs.

69buickgs (author)2015-08-28

What's the max current/voltage anyone has tried to put into the MOT secondary without a meltdown?

muttyfutty (author)2009-08-27

I currently own an MOT and it is working fine, except for the fact that the primary windings get very hot during operation (after 10 seconds of arcing) I am connecting it directly to the Mains (240V) I have mesured the imput (Mains current) to be 10A ++ Is there any way to limit the input current to prevent heating in the secondary windings On another note, is it possable if I had 2 MOT, to connect them in Parallel in order to get greater ampage output, and if so how Sorry for the long question! :) Thanks in advance! Mike

DevCoder (author)muttyfutty2009-08-27

The reason your primary gets so hot is because the MOT isn't ballasted. See step 6 for a schematic. Also, it is possible to get 2x the current, connect them in parallel like the schematic in step 4 (use the transformers bases as the other HV out)

muttyfutty (author)DevCoder2009-08-29

Thanks, Prob is that I only Have 1 MOT, is it possable to current limit by putting a 150W light bulb in series with the primary? Thanks

DevCoder (author)muttyfutty2009-08-30

you can, keep in mind that a MOT usually uses 1500W of power, the light bulb would be decimated.

muttyfutty (author)DevCoder2009-08-31

I've got an 150W halogen bulb. will that work or do I need a larger value? what do you reccommend?

tony54 (author)muttyfutty2015-08-15

MOVs are very dangerous to use. Use a 5w bulb in series or maybe a 25w bulb. This can still easily kill someone so I wouldn't use it. Use a small neon transformer to make a tesla coil, since it is much safer. You will get much larger arcs and is will be much safer since it is low current and high frequency. I am talking about the small table version of tesla coils, not the huge ones some people make. Radio Electronics had an article in the 80s or 90s for a coil that would make 20+ inches of arcs in the air and it was still safe for people. And there are others in electronics magazines. But all of these can destroy nearby electronics just from the static field. The tesla coil below should also be able to make 20+ inches of arcs or lightning in the air around it.

I have plenty of experience with high voltage electronics and even I wouldn't feel safe using an MOT like this. Stick with tesla coils instead, they make bigger arcs and are much safer. Like here.

Plans for 250,000 tesla coil. And it includes many other tesla coil links.

M2aestro (author)muttyfutty2015-07-14

You are going the wrong direction with the power of the bulb; too little resistance. Get the lowest wattage bulbs you can use for the current you think you need. Don't put them in parallel, for you would have defeated your purpose.

DevCoder (author)muttyfutty2009-09-20

i still recommend another MOT, just go dumpster diving a little

muttyfutty (author)DevCoder2009-09-20

Thanks, still trying to get that MOT. but I have saucessfully used a 2200W kettle in series whith the primary, NO HEAT!!! yay! but the water in the kettle starts boiling everytime I arc it lol

DevCoder (author)muttyfutty2009-09-21

LOL! You should make some pasta with it :D

muttyfutty (author)DevCoder2009-09-23

yep, pasta and high voltage, a pretty good combo (what about the sauce?)

LuciferTengu (author)muttyfutty2009-12-05

use the arc to "euthanize" a crab or two and make a bisque

muttyfutty (author)LuciferTengu2009-12-06

wow!, I never thought of that...
Problem is that when I use the kettle as ballest the arcs are reduced to about 1cm as opposed to the 15cm ones I got when ran with no kettle..

croslandjr123 (author)muttyfutty2010-10-22

Yeah, I tried ballasting one of my MOT's, sure it stops it from overheating but the major downside is that you get tiny arcs. that's why I don't normally ballast. I just use a powerful fan from a microwave oven to TRY and cool it.

M2aestro (author)2015-07-14

I think this instructable invites those poorly educated in electronics and safety to risk serious injury or death to self or helpers. I believe the writer should have thought more about how to proceed with a much safer mechanical layout, grounding where appropriate, etc. BTW, there are appropriate high current plugs that are standard for high current devices, and I would not use tandem plugs. Convert an outlet to a single receptacle that is rated for the highest current for which the supply lines are rated. Check your ground!

Xylit0l (author)2014-02-13

Use class 1 gloves minimum if you plan to build this

gobitz (author)2009-06-25

I suggest using something more HV proof than a piece of 2x4. Wood can conduct electricity and I have gotten an MOT to arc off a dry piece of wood and concrete!

houdini0118 (author)gobitz2012-04-27

concrete is actualy a conductor a poor one but it dose conduct it is used in alot of higher wattage resistors

modog4000 (author)2011-01-29

how do you build a ballast

HVahead (author)modog40002011-10-04

HVahead (author)HVahead2011-10-04

nvrmnd thatnot an actual instructable...

bryanb333 (author)2009-11-04

a cool thing to try with this is clamp a penny to one output and a nickle or some other metal to the other then make the arc.... half of te arc will be one color the other half a different color alsotr somthing gold plated if i remember correctly you get a bright white core whit a bluish sorta flame the pennies will be greenish ... lol we did this in my electronics class in high school :D

BobS (author)bryanb3332009-12-08

copper,  nickel and other heavy metals used in coins form very toxic fumes when vaporized. Even welding of zinc plated steel without fumes being extracted is very bad for the lungs.

toxic like disabled toxic, or dead toxic, not just cancer or COPD toxic!!

bryanb333 (author)BobS2010-09-01

Also Note that whenever and arc is present you are actualy creating O_3 which is also poisonous it can cause sufication or something along those lines the molicules are larger than ur normal O_2 molicule

Jimmy Proton (author)BobS2010-08-04

ewh, metal smoke! don't breath this!

Plasmana (author)Jimmy Proton2010-08-26

Haha! "Will it blend? That is the question" I love his shows

Jimmy Proton (author)Plasmana2010-08-26

hahahaha me to

jbyrns1993 (author)2010-06-25

I have a MOT that I am afraid to plug in, even though I have experience with 20KV. Is it possible to re-wind the secondary to give high voltage but very little current? I want like 20ma or less.

DevCoder (author)jbyrns19932010-06-25

The thing is, at only 2 kV, a MOT won't jump the air to your hand. Even so, I either wore a pair of 3 mm rubber chemical gloves or attached the wire to the end of a long wooden stick. You can rewind it, but you would be winding it with wire thinner than what is currently on there, and you would have to wind it many, many more times. Basically, it's not at all worth it. Instead, just take all the safety precautions you can.

Highjump44 (author)2010-03-02

 can u explain the stick 
 and wat two contacts is the spark jumping from

Highjump44 (author)Highjump442010-03-02

 pin 10 hv out and ground right    
 but wats the stick for,    pressing the switch and moving some metal thats connected to ground and the terminal of pin 10

Musicman41 (author)Highjump442010-03-28

The stick is an insulator, meaning elecricity does not move through it.  It ensures that the electricity goes through the termanals, making a spark, instead of through his body and heart, causing a heart attack.

tristantech (author)Highjump442010-03-25

The stick is used so the author can touch the wires together with out burning or electrocuting himself.

rimar2000 (author)2009-02-02

This is very good work, but look

Seems Tim Anderson said you...

DevCoder (author)rimar20002009-02-02

While I do admit I got some of the ideas from that Instructable, the similarities end there. This setup gives off around 2kV at a low amperage (if anyone knows the amperage, I would love to know it), while a welder uses a relatively low voltage at a very high amperage.

wbreslin951 (author)DevCoder2009-06-04

like xellers said, these transformers put off a crazy amt of amperage. 50 mA from one hand to the other is enough to kill you, and MOTs put off abt 500 mA depending on the wattage of the Microwave u got it from.. if u got a shock from say one finger to the other, it could seriously injure your hand, but chances are u'd survive it. but even then high voltage is a completely different animal.. you could be grounded somehow, touch the wrong wire and BANG 500 mA straight to ur heart..

muttyfutty (author)wbreslin9512009-12-06

I agree!
I did more mesurments and descovered that the 2KV reduced to 500V at 1.5A when pulling an arc...

About This Instructable



Bio: Devin is a cool guy, eh doesnt kill himself while doing stupid things, and doesnt afraid of anything.
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