The microwave over transformer can handle Watts of power or more. It is therefore a good alternative as a cheap high power transformer, if proper modifications are done: It is possible to remove the high voltage windings and instead add a few turns of thick wire, for a low voltage, high current transformer.
Before starting to wind the secondary, we need to know how many turns we need for a given output voltage. In my case I needed 3 separated secondaries, one for 6. The first two are for powering filaments of high power vacuum tubes.
In my case the ratio was 0. For 6. Not easy, but do-able.
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I used PVC insulated wire not the best choice but it was all I got1. So my 3 secondaries can output the following voltages: 6. I m thinking to build a MOT with enameled copper wire at the secundary,at Hi Roger. Yes it gets hot because the iron core gets very close to saturation. For minimizing headaches with your amplifier, I suggest you get a proper transformer for this task.
A fan cooler will not help, as it cannot push air deep inside the primary coil, so the wire would eventually burn with a bang. Roger, Way too later of a reply but I will post it anyway. If you want to power car audio equipment on the cheap look into server power supplies on ebay. Try to get one with a built in fan. They are capable of more than W at If you do get one look on RC groups website in the batteries and chargers section for the pin-out because cucinotta: eravamo più amanti che coniugi.
ora mi risposo, e will need to make a jumper to power it on, you may also find out how to raise the output voltage to Radu, Great website, Somehow Ive stumbled in here and each time Ive found something interesting. I love messing around with MOTS but I always take off the secondary because as you know that secondary will more than likely kill you.
Im a electrician with 25yrs experience and work on 3 phase V industrial equipment live all of the time, but Im scared of that MOT secondary!DIY Arc Welding Machine - 4pcs Microwave Transformers
Hello Radu. I was looking into AWG tables and realized that if one use several smaller gauge wires to compose a target area section, in order to hold more current, one will note that by the AWG tables, 2 smaller section wires that hold a total sectional area the same as a thicker wire will withstand more current probably due to surface-current.
Do you agree? Best regards Lissandro. I have seen several comments recently about surface current or skin effect.I wanted to make a arc welder with a homemade transformer. I am going to copy a microwave transformer primary windings and have 20 turns of 10 AWG wire for the secondary so I get 20 volts but very high amps.
The problem is that I don't know what AWG and how many windings there should be on the primary. So if someone knows or can take a look at one if you have one that would be great!! You are going to have to think a little bigger than you are. Arc welders current is usually in the order typically between 17 to 45 volts and to amps. At that current, you need large cross-sections on all wire or the temperature rise will be too great. You want the work to melt, not the wire. Your 10G comes no where near large enough.
Also, the transformer will have to deliver appreciable power. I wouldn't consider anything less than 2kVA and preferably somewhat larger. Well, if you want to get 20 volts out of a turn secondary you would need turns on the primary. Check a wire table for the size appropriate for that current. I am concerned that with so few turns, there will not be enough inductance in the primary winding to avoid a high no-load current.
When you energize the transformer, do it with low voltage or put a W light bulb in series with the primary winding to avoid a high current until you can see what will happen. Trending News. Hailey Bieber endorses Biden — while dad backs Trump. Trump turns power of state against his political rivals.
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Rewind a Microwave Oven Transformer
Steel yourself emotionally for colder weather. Dak Prescott suffers awful-looking ankle injury. These restaurants filed for bankruptcy in so far. North Korea unveils new weapons at military parade.I had no idea making a DIY welder would be so easy to do.
And, it's pretty much FREE! Additionally, the stick welder you get is definitely better than anycheap commercial welder you can buy. Why is this homemade thing better than something you can buy?
Because when you factor in shipping and labor and the little bit of retail markup - the companies that make typical cheap buzz boxes will skimp on copper as much as possible. Whereas you can use enough copper in this to make something really juicy, and still spend less, to nothing, compared to a store-bought arc welder.
So here's what you need to build a welder: - Two beat up old microwaves - Some 10 gauge wire - Wire nuts People throw out microwaves all the time, if you keep your eyes on the curbs. Try the warehouse that processes donations - they have to pay to get rid of tons of broken ones.
You could die and you could go blind. That said, try this at home! See this for a lot of welding safety tips Here are the really good how-tos that this project is informed by: build a 70 amp welder the tiny tim welder by tim williams home made welding machine via afrigadget Dan Hartman's how-to is good for reference, too.
And here's the quickest way to make a DC welder with a bunch of 12 volt batteries. Invite your non-hardware oriented pals over to help help dissect your donor appliances.
They'll love it. David Grosof donated one of these microwaves under the condition that we take it apart together. Good safety tip: You'll find a gigantic capacitor inside the microwave.
It looks like a metal can with two tabs on top. Short it out to make sure it doesn't have any leftover charge on it, before you poke your hands anywhere near.
Just put a screwdriver or something metal you aren't connected to, across the two metal terminals shown here. Chop and and knock out the secondary thin wire windings. Don't nick or damage the primary windings in any way. If you do, you could create shorts where two windings conduct to each other, allowing electricity to bypass certain parts of the coil, making effectively a smaller coil, and creating something different than what you expect at the output.
Or, you might chop the connection entirely, ruining the primary. So do your best to keep it intact. We scavenged some heavy wire from an old powerboat the owner was scuttling. We stripped the outer jacket off and separated the inner conductors to wind new secondaries on our transformers. We wound 20 turns of guage wire on each transformer. That's just about how much wire would fit into the available space. It took a little over 20 feet of wire each. How does a transformer work?It looks like that may have been the inspiration for this build, and the finished product appears to be a tad more useful this time.
A shallow dish is fabricated out of steel and the magnets are welded in place. With the primaries wired together, the magnets are epoxy potted, the business end is faced off cleanly, and the whole thing put to the test. You can wind arbitrarily many turns in a coil and create ridiculous magnetic fields, but the series resistance grows to the point that adding more turns decreases the current and diminishes the field.
If I remember right Edmund sold a one ton lift magnet that would work with one dry cell. It was about 3 to 4 inches in diameter and half as thick with a single piece of iron with a circular groove for the coil. I saw a similar magnet lift a car at the Museum of Science and Industry in Chicago decades ago. The trick is perfect flat coupling to a thick flat piece on the load. No electricity involved. The kg version has a bigger handle :. Colin Furze has made magnetic shoes using same transformers two years ago:.
Does matter since he runs it on DC, even so the lamination are already welded at the factory, its how the transformer is assembled. I love the concept and the build. But does potting with epoxy resin have enough strength to hold magnets in place? I did not see any mechanical fastners holding magnets in place. If epoxy cracks I see magnets pulling out of metal bracket and failure. Over to someone with engineering experience please. He welded the base of the magnets to the plate that is hold directly to the crane with a hook.
Look again. The sole purpose of the epoxy would be to keep the coils mounted to the cores as well as keeping them free of damaging debris that would short the coils.The microwave oven transformer is possibly one of the simplest methods of making some big high voltage arcs, mainly because they are robust, cheap, and easy to hook up. To the bottom left I have a picture of an MOT. The mains input is two blade connectors on the primary coil thick wire.
But where does the 2,V come out? Well, the HV output is a single blade connector on the secondary coil. It usually puts out around 2,V at 1 amp 2, watts ; certainly more than enough to kill you, so… DO NOT make contact with the high voltage! MOTs are a mass produced item and these days quantity is more important than quality.
Because of this, they are designed with as little iron as possible and drawing an arc often saturates the core. Once a transformer is saturated it starts to draw a lot of extra amps; amps that do not make it to the secondary coil, but instead are wasted as heat. To prevent excessive current draw MOTs are usually ballasted, and this can be accomplished a couple different ways.
By far the simplest method is just to use a long wire wrapped around some steel rods. An alternate ballasting option is to use another MOT an a series inductor. The one with the shorted secondary becomes a high current inductor, perfect for ballasting another MOT. It certainly adds a lot of weight though…. A third method of ballasting MOTs is to use a resistive ballast.
Halogen lamps the big W work lamp kind make pretty good resistive ballasts. Of course if you have a 30 amp circuit you can always just hook the MOT directly to the mains and pull some mean unballasted arcs! Since MOTs are nothing but copper and iron they can be modified a couple different ways. One such modification is to knock out the magnetic shunts. If you want more current out of the HV side for some reason you can knock out these shunts using a hammer and a chisel.
Another possible modification is to turn the MOT into a nice low voltage high current transformer, and I discuss that in detail on this page. Some sites and videos found on You Tube seem to make it sound sooo difficult.
So it would be work for my amplifier plays some music for at least a couple of continuos hours? Hi Adam! I am a first timer at this website. I really am into electrical items of all types, but especially seeing arcs of all kinds come from high voltage wires. The MOT transformer interested me here because of how simple it was to do your own custom high voltage with it.
Some MOTs have different high amperages used through the outlet.Welcome, Guest. Please login or register. Did you miss your activation email? This topic This board Entire forum Google Bing. Print Search. Qmavam Regular Contributor Posts: Country:.
how many windings are on a microwave transformer primary winding?
I find the Primary magnetizing current is very high. Another group said I needed to add primary turns. I'm trying to figure out where to stop adding turns. I have a graph showing the original, with 37 turns added, 48 turns added and 60 turns added.
Can anyone look at the graph and say, that's good enough, put your secondary on. The 22V secondary will have an 8 amp load. The desired magnetizing current is up to you. You can reduce it but then the maximum power the transformer can deliver is also reduced. I think the function is roughly reciprocal ie. I remember reading an article somewhere that described the rationale behind MOT design. It's worth a read if you haven't seen it.
Build a Microwave Transformer Homemade Stick/Arc Welder
I understand that for the most part, MOTs run at full secondary current except during the time that the magnetron's heater is warming up and the anode current is reduced.
Because the secondary load current cancels out the magnetic flux developed by the primary current, increasing the secondary current moves the transformer away from saturation. The designer can then use a smaller core that can saturate at a lower primary voltage than for equipment that does not operate at full current.
Bottom line, if the transformer will not operate at high load current almost all the time, the losses due to the magnetizing current can be significant. My use is to power a Battery operated leaf blower. The battery and charger are gone Yes, I'll use a bridge rectifier. It will draw 8 amps when running and 0 amps when the leaf blower is switched of.
I can't make sure power to the primary will always be switched off, so I should lower the magnetizing current. I should not have much problem getting a watts from a transformer that did output watts. Any other advice? I see why you are lowering the flux density in the transformer, but it has consequences. You will need more turns on both windings, so copper losses go up.Pages: .
Machine shop metal 5 years, with lathes and mills manual and CNC. I'm an artist and musician, compose my own music, paint draw. Microwave transformer rewind trick: calculating amps and voltage.
Ok, so if I take the secondary coil out of the microwave transformer, and wind up my own coil wire. I believe the gauge of wire is how much current I can pass through, if I'm not mistaken. How do I calculate how much voltage it will convert?
Can I do it in the reverse direction, apply voltage to my re-wound coil, and use this metal brick to step-up the voltage - say 4 times? Re: Microwave transformer rewind trick: calculating amps and voltage. What's special with a microwave transformer? Edit ; have you seen this video. Yes, step up 24v to 96v. I watched tutorials explain how easy to re-wind the coil, to produce high current 24 volts or something to use it as a welder, from a v ac line.
I would like to go in the reverse direction, and wind it up receive 24 volts from lead batteries into secondary re-wound coil, and use the the original v primary coil to drive a motor and hopefully get about 30 amps.
Is there complicated pulse circuitry that needs to get involved - or is it a matter of winding these wires the right way with some basic capacitors?
You cannot "transform" DC directly. The first thing you need to do is convert the DC into AC and for that you'll need some form of 'low frequency' inverter rated in excess of whatever power you want to get out of your steel-cored microwave transformer.
So any inverter you build will need to output in excess of 3kW. Considering a 'standard' microwave is usually rated at around to watts, there's no way you will get 3kW through that rating of transformer core. Quote from: DocStein99 on Sep 09,am. Ok - that was the MYSTERY part of my question: I did not know that AC part of the transformer had anything to do with it, and just thought it was power being manipulated and did not matter what direction it was driving. Since this is complicated, I'm going to put this away and leave it alone.
I don't get much pleasure out of sawing and weaving wires through a heavy metal brick anyway. There might be more than one way to 'skin your cat' so if you tell us what the motor is and what you are endeavouring to do with it you might get some constructive ideas.