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):

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Step 1: Disclaimer

Picture of Disclaimer
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

Picture of What You Need
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!
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M2aestro17 days ago

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!

muttyfutty5 years ago
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)  muttyfutty5 years ago
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)
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)  muttyfutty5 years ago
you can, keep in mind that a MOT usually uses 1500W of power, the light bulb would be decimated.
I've got an 150W halogen bulb. will that work or do I need a larger value? what do you reccommend?

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)  muttyfutty5 years ago
i still recommend another MOT, just go dumpster diving a little
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)  muttyfutty5 years ago
LOL! You should make some pasta with it :D
yep, pasta and high voltage, a pretty good combo (what about the sauce?)
use the arc to "euthanize" a crab or two and make a bisque
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..
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.
tony541 year ago

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.

M2aestro tony5417 days ago

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.

Xylit0l1 year ago

Use class 1 gloves minimum if you plan to build this

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:

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.
gobitz6 years ago
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!
concrete is actualy a conductor a poor one but it dose conduct it is used in alot of higher wattage resistors
modog40004 years ago
how do you build a ballast
HVahead HVahead3 years ago
nvrmnd thatnot an actual instructable...
bryanb3335 years ago

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 bryanb3335 years ago
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 BobS4 years ago
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
ewh, metal smoke! don't breath this!
Haha! "Will it blend? That is the question" I love his shows
hahahaha me to
jbyrns19935 years ago
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)  jbyrns19935 years ago
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.
Highjump445 years ago
 can u explain the stick 
 and wat two contacts is the spark jumping from
 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

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.
The stick is used so the author can touch the wires together with out burning or electrocuting himself.
rimar20006 years ago
This is very good work, but look http://www.instructables.com/id/Build-a-Microwave-Transformer-Homemade-Welder/

Seems Tim Anderson said you...
DevCoder (author)  rimar20006 years ago
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.
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..
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