Hello,
This instructable explains how to make a spot welder from a MOT (microwave oven transformer).
The primary coil (thick wire) will still be used as primary windings. The secondary coil (thin wire) will be replaced with very thick wire of less windings.
Warning:
Do NOT plug in this transformer before it's ready. Especially not when the original secondary windings are still in there! This device outputs an extremely deadly high voltage. You have been warned!
Also, as in all my other instructables, read all warning notes! I'm not responsible for any accidents.
Test video:
Another video:
This instructable explains how to make a spot welder from a MOT (microwave oven transformer).
The primary coil (thick wire) will still be used as primary windings. The secondary coil (thin wire) will be replaced with very thick wire of less windings.
Warning:
Do NOT plug in this transformer before it's ready. Especially not when the original secondary windings are still in there! This device outputs an extremely deadly high voltage. You have been warned!
Also, as in all my other instructables, read all warning notes! I'm not responsible for any accidents.
Test video:
Another video:
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Signing UpStep 1: Requirements
- a MOT (microwave oven transformer)
- 3 female slide connectors (not required, you can also solder the wires)
- wall plug with ground terminal
- pliers
- cutting pliers
- drill with thick iron drill bit (10mm or so)
- iron handsaw
- wood saw or jig-saw
- 1m thick 2 gauge flexible wire (1 meter) (if you don't have this, check step 5)
- a volt-meter (or multimeter)
- a wooden shelf (see step 7)
- some other small wooden pieces (see step 6 and 9)
- 3 female slide connectors (not required, you can also solder the wires)
- wall plug with ground terminal
- pliers
- cutting pliers
- drill with thick iron drill bit (10mm or so)
- iron handsaw
- wood saw or jig-saw
- 1m thick 2 gauge flexible wire (1 meter) (if you don't have this, check step 5)
- a volt-meter (or multimeter)
- a wooden shelf (see step 7)
- some other small wooden pieces (see step 6 and 9)
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I think that you may even put 2v directly on to your hart without any problems.
It's just a little more than an AA battery.
Even low volts can stop your heart if it travels through your body just so.
Also wear dry welding gloves and use a darkened arc welder's mask if you do any arc welding.
Codongolev told you this,important thing is that you NEVER touch wires without insolation.
Electorials,nice job.Thank you
Now don't come tell me 'high current kills you' because with 2V it's impossible to get high current trough your body!!!
This thing *can* produce high current, but because the resistance of our body is too high for that, you get extremely minimal current when touching the leads.
This case is totally safe since it works on 2V
Now don't come tell me 'high current kills you' because with 2V it's impossible to get high current trough your body!!!
Your statment is flawed, I'm sorry...
If the voltage drops, and the resistance stays the same, the current Drops too.
Trust me, I am in Electrical Engineering, but I find so many colleagues that have no idea of basic principles.
As codongolev said in the first post, THIS WILL KILL YOU.
Here is how:
Skin resistance on the order of 2-3 megaohms (this is 2 to 3 million ohms).
2 volts divided by this high resistance, you won't even feel it (yes, it is just slightly higher than an AA cell).
However, the internal resistance, that is through blood, due to iron on our blood, is in the order of milliohms (we're talking something small times 0.001 ohms)
Now, 2 volts divided by that is a lot of current.
The ability of the supply high current at a specific voltage is what determines its power.
But trust me, a single alkaline AA cell can put out (when new) about 7 amps of current.
This does not mean you'll be in any way hurt if you touch it. However, if you have a wound, don't you dare come close to that...
So the moral is, if you do not need to touch the leads - don't.
If absolutely needed, make sure your hands are dry and have no major scratches... Maybe wear thick rubber gloves (electrician's gloves or something)
Hope I made things clear and maybe (just maybe) saved someone's life :)
You can thank me later
If what you say is true, we would all better use tubes filled with blood as conductors for all our electrical applications because this conducts a lot better than copper wiring!
So you say 0.001ohm as resistance for our blood. I'll take you mean something like 1m distance for that.
The resistance of copper wires, 2.5mm² (used in home installation wiring), is 7.4mOhm/m (0.0074ohm/m)
The actual resistance of our internal body is 200-1000ohms. That doesn't really look like 0.001ohm right?
"Please ask someone who understands Ohm's Law clearly."
That was funny.
"a single alkaline AA cell can put out (when new) about 7 amps of current."
That would be a fast 15minute chargable NiMH battery.
Now, back to the point:
MOT welder voltage: 2V
Internal body resistance: 200ohm
Ohms law: Current = 10mA
-> You'll feel that, but you'll survive.
In order to cause 10mA of current externally, you need 10mA*2MOhm=20kV
Yes, I have exaggerated some numbers to make the while thing look impressive, but I know of a guy who died because he wanted to measure his internal resistance.
He poked his fingers (thumbs, I think) with Ohmmeter probes - died almost instantly.
And if you don't believe me, take a brand new AA cell, and conect a 0.1Ohm power resistor to it (looks like a plaster brick) and measure voltage across.
If you measure anything above 0.5V, that's your *at least* 5A of current.
(An Ampere-meter applied directly to the battery leads might not give you the right answer since the Am-meter usually has higher internal resistance)
60mA (0.06A that is) of AC @ 60Hz can cause fibrillation. 20mA can get painful.
Someone said that voltage causes pain, but current kills, VOLTAGE AND CURRENT ARE RELATED!!!!!
When a teaser sends 50kV to someone's body, first, it is pulsed 50kV, so the average voltage still has to be under whatever level to keep average current within safe level. The teaser continuously measures the output current and makes sure of this. That's why there are relatively few deaths from teasers (usually people with weak hearts).
Works like this: say you pulse something at 1% duty. this means that 1% of the time the 50kV pulse is on and 99% it's off.
If you need higher voltage, you just pulse a higher duty cycle, say 1.5% or 2%, etc. The period stays the same, but the time on and off changes.
Please read more about PWM (Pulse Width Modulation) and where it's used.
We certainly do die from current, but the two are related and nothing changes that.
If you want to go in-depth, during transient, Ohm's law still applies, but on an infinitesimal scale. Eventually it all stabilises and Ohm's law still works.
Understand this or not, please do not touch the leads unless you have to, in which case, practice extreme care.
P.S.
Never meant to insult anyone. Sorry if I did.
And yes, I do think yo insilted me, twice now.
As you can see many of the readers are not from the electronics / electric fields and lack the basic understanding .
You are a OK ! 100%
Nice work .
how about we stick to this and be done with it?
Right here: "Now don't come tell me 'high current kills you' because with 2V it's impossible to get high current trough your body!!!"
Poke your fingers and you if not die, will at least suffer severe internal burns.
Just as much as with one or two AA batteries.
2V/200Ohm=0.01A=10mA
This current INTERNALLY, will not just kill, but most likely will fry a human.
You may try it yourself, but I will not accept any responsibility for your actions (please don't). :)
And for real, I am sorry for insulting you. I did get carried away and said a few things I now regret.
What I wrote was meant to be educational for general public, so let's just agree with codongolev and keep it at not touching the leads unless absolutely required...
Peace.
so well yes, you will indeed get shocked if you poke the connections in your fingers.
And it's no problem :) (I mean the discussion)
Few Questions;
1- What type of microwave i need? Do all of them work?
2- Can i solder Sub C type of batteries?
3- Is there more "rookie" or "starter" type of information for people like me? (I used to have billion questions like why did you make 2 turns, why this, what that , what is that red cable , where em i etc... (= )
and finally returning back to basics, it is 4 am now and i must still master my soldering skills (yes..)
Trust me, I have already built one for the same purpose and its not usable.
The current is too high and the voltage too low, plus its uncontrollable.
If you are serious about making a spot welder for batteries look up
"capacitor discharge spot welder" or "CD welder".
I ended up soldering the cells.
You will need a big soldering iron (80W or more) and some skills,
but its not impossible at all.
I wouldn't solder to any type of batteries if I was you, but if you can do it quickly, it shouldn't be a problem.
There is no 'rookie' information here, but you can ask anything you like here in the comments.
I made two turns because the less turns you have, the more current you'll get. Using just One turn didn't work well any more because then, the output voltage got too low.
What red cable are you talking about?
The red cables on the first pictures, they were there from the beginning. I removed them.
Regarding the risks of electricity.
ASSUME ALL ELECTRICITY CAN BE FATAL. People have been killed by very small voltages while others have survived lightening strikes. There is no hard and fast rules. Yes it's the current (amperage) that does the damage, but that is related to voltage and resistance.
I can easily put my phone charger to my tongue without a problem. It's rated at around 500 milliamps, but the electricity's easiest path would be along the moisture of my tongue. If I stabbed the individual wires into each of my thumbs (creating a path with my heart closer to the middle) it may kill me. It may not, but I won't test that.
I didn't see it mentioned. Think of electricity as a river. Voltage is the the size of the river (width) and amperage is the speed of the flow. A wide lazy river would be a high voltage, low amperage. A set of rapids would be akin to lower voltage and higher amperage. The Amazon (which looks still in parts) is high voltage and high amperage. A pond would be a high voltage and minimal amperage (if you consider evaporation the flow). A shallow river that you can walk across could drown you if the current sweeps you off your feet
Just take precautions when dealing with any electricity. The analogy sucked, I sure somebody will do a better job with it.
When someone creates stuff that works on 110V, people know it's dangerous, and nobody starts talking about 'oh noo this is super dangerous, beware, this might kill you, ...) but right now, when the voltage is +-2V people suddenly feel like they need to keep going on about that. imo, 2V is still 50 times safer than 110V if the human resistance stays the same.
I know that poking wires into both your fingers with 2V is dangerous, but then again:
Why keep talking about those dangers if poking a 9V battery into your fingers is More dangerous?!?!
So unless your body resistance is less than 400ohm, please stop talking about this stuff...
Oh, and keep in mind that when measuring the resistance of your body, your multimeter probes have a tiny voltage across them which might kill you if you stick the probes across your heart .. -_-
What about splinters? or flying molten metal?
Don't burn yourself, now I feel good about saving the world one burn at a time...
Dry air and floor are vital as electricity resistant gloves ...
Electricity is no game ...
Be sure you don't bet your life !
The dangers of electromagnetic radiation became apparent after World War II, when certain diseases started appearing with greater frequency among WWII radar personnel. Since then, the science and medical communities have produced a crush of evidence that exposure to radio frequencies is linked to cancers, brain tumors, lymphomas, headaches, melanomas, leukemia, Alzheimer’s, memory loss, Parkinson’s, Huntington’s, high-blood pressure, and brain damage.
That is really excellent information about the dangers of unshielded magnetrons. You should post it on any Instructables that suggest the use of magnetrons, particularly unshielded ones!
This Instructable, however, has nothing to do with magnetrons. It's about re-purposing a transformer that originally powered a magnetron. You could conceivably do the same with a transformer that once powered a rotating anode x-ray generator, or a search light, but it wouldn't be necessary to warn readers about the dangers of x-rays or damage to the eyes from bright light.
When you post a comment saying "By all means, never never do this!" you should make sure you know what you're talking about. It's unfair to the author to have people warned away from a very good Instructables project by a confused concern troll.
See how long you'll survive there.
Then decide which is more deadly :D:D:D lol