I'm also making an RSU out of a 2T with no center taps to test the 120V motor speed controllers for amp adjustment. It should be capable of a max 2V / 500A.
DIY MOT-based Resistance Soldering Unit (RSU)
- Thread starter spinningmagnets
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reserved for more pics
The good news is that, both of the "motor speed controllers" seem to work for adjusting the amps...up to a point. You can dial-up the amps, and dial them down, but...at the lowest setting I was still pulling 120V X 3.3A = 400W from the wall, then the transformer was converting that into roughly 400W / 2V = 200A.
For a subject, I was using long steel razor blades and solder, and trying to connect 0.25mm copper ribbon to the steel. The solder started to melt, but the steel was glowing red-hot way too fast from the 200A. I'll keep one of these big transformers for future experiments, but if I am going to be able to solder copper onto cell-tips with this, I'll need a much smaller amount of copper mass passing through the transformers magnetic field. If the copper mass in the secondary winding ends up much smaller, then there's no need to get a huge transformer. This first version is using the fattest cable that would fit. #2 welding cable with only two turns...
I have a several of these big MOTs (1500W), and one of the others has a 2/4/6T winding set using 6-ga
Here's a good clamp for the electrodes. Tin-plated copper http://www.quickcable.com/products.php?pageId=326
For a subject, I was using long steel razor blades and solder, and trying to connect 0.25mm copper ribbon to the steel. The solder started to melt, but the steel was glowing red-hot way too fast from the 200A. I'll keep one of these big transformers for future experiments, but if I am going to be able to solder copper onto cell-tips with this, I'll need a much smaller amount of copper mass passing through the transformers magnetic field. If the copper mass in the secondary winding ends up much smaller, then there's no need to get a huge transformer. This first version is using the fattest cable that would fit. #2 welding cable with only two turns...
I have a several of these big MOTs (1500W), and one of the others has a 2/4/6T winding set using 6-ga
Here's a good clamp for the electrodes. Tin-plated copper http://www.quickcable.com/products.php?pageId=326
ridethelightning
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- Jul 21, 2013
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great stuff! bookmarked for later. 
The type of dimmer you need to handle a inductive load is called a Magnetic Low Voltage Dimmer, they are made to adjust the input voltage 0-120vac to a step down transformer/low voltage for lighting. I leave the shunts in my rewound MOT's because the transformers already draw too much current for their physical size. Shunts keep the current to reasonable level, they are going to saturate and get hot anyway so just don't push them to much as in a rsu. Spot welding is a different story, they
can stand the overload for milliseconds, but for rsu at 3-5 seconds , well they just get to hot.
can stand the overload for milliseconds, but for rsu at 3-5 seconds , well they just get to hot.
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