While I tinker with my other projects I want to replicate Robert Alexanders AC/DC motor patent. I mentioned this patent in another thread (
https://patents.google.com/patent/US3913004A/en )
I have 3 Treadmill motors from free treadmills, so I am sacrificing one for this project.. I am choosing this motor because it has a nice BIG armature and a long enough shaft. I need it larger because I need to get 2 windings on here + extra slip-rings.
I removed the armature and it was covered in epoxy, even the commutator hooks. There was no way I was going to clean this thing off. So I cut all the wires with an angle grinder, removed the commutator and bearings with a bearing removal tool and cooked it in a fire.. I probably damaged the lamination insulation but none-the-less I got the armature clean and in 1 piece. So I hope it's still satisfactory.
I wanted to buy a replacement commutator but could not find one with the right dimensions, so I had to resort to grinding off all the hooks and epoxy, drilling the bars, and soldering 14 AWG into the holes to make new hooks. Surprisingly, they came out solid with no shorted contacts
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You may not be able to see, but I 3d printed end covers for wire protection at the ends.
I next have to make slip rings before winding this up. And of course the original housing, magnets, bearing holders, brushes, etc are all questionable as of what can be reused. But I think I can manage that either way. The hard part is getting a usable armature that can fit 2 sets of windings and a long enough shaft to add sliprings.
Any which way, I have to know if this patent is legit, as the author paid the dues for decades until it's lifetime expired. And I have yet to see a real FULL replication besides one person tapping the original windings and not adding a separate output coil.
(09-22-2025, 06:19 AM)unimmortal Wrote: [ -> ]It seems like your last RT build + Tee emulated this... I was initially a little confused; but after reading up a bit and visualising the diagrams in the patent - it is the same effect.
https://www.rexresearch.com/alxandr/alexandr.htm
Yes the other thread was trying to do this but in a different manner. The output coil is induced by a rotating field that physically rotates with the armature, while that same coil is also rotating past stationary magnets being induced.
Before going too far down the rabbit hole trying to alter the method, I want to try the patented way to see if the effect is real.
This channel actually tried 4 real replicaions.
https://www.youtube.com/@electricity52nn89
Here's what I notice:
On 3 of the attempts, he did roughly the same winding pattern, in which he wound 2 output coils 180 degrees apart. On 2 of these builds, he reports some effects starting to manifest.
Then on his 4th attempt, he tried a 3 phase output coil, which did not show any interesting effects.
see the image from 4 stills of his builds. I outlined the output coils in yellow.
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The patent says this;
Quote:“The rotor comprises a transformer core subjected to and having a primary motor-transformer winding and a secondary transformer-generator winding, both of which are wound in the same slots of the armature core.”
Plus, the simplistic drawing shows the outout coil taking the exact same path as the primary. I think when he wound the output coils like he did, he was basically sampling the field instead of synchronizing with it.
I take his quote to mean the output coil follows the same path and in the same slots as the primary. So I am thinking the output coil should lap around the armature the same as the output coil. I think (hope) it may work cleanly if the coils are geometrically synchronized—same path, same pitch, same direction.
So that's where I am headed.
what's crazy is that builder in the last post appeared to just wrap the armatures with no protective layer between the armature laminations and the magnet wire. That's just asking for a short!
If you look at the pdf patent Fig2 & 3 from the link I posted. Item 16 is the stator and appears to be coils on the outside and either side of the armature, and not wound into the armature. Looking at the vids, there was a comment regarding extra magnets that are not mentioned. Interestingly Tinman was doing something with magnets in the stator as well.
All in all, you're going to make a buttload of power if you keep it all tidy. Nature tends towards perfection.
(09-22-2025, 09:10 PM)unimmortal Wrote: [ -> ]If you look at the pdf patent Fig2 & 3 from the link I posted. Item 16 is the stator and appears to be coils on the outside and either side of the armature, and not wound into the armature. Looking at the vids, there was a comment regarding extra magnets that are not mentioned. Interestingly Tinman was doing something with magnets in the stator as well.
All in all, you're going to make a buttload of power if you keep it all tidy. Nature tends towards perfection.
The AC/DC motor has stationary field coils on the outside. if coils are used (like vacuum cleaner motors) then it can be fed with AC or DC.
Permanent Magnet DC motors can only operate with DC because the stationary permanent magnets can not change polarity like coils can.
The stationary field poles can be either coils or magnets, according to the patent. But for the reason above, if magnets are used, then DC must be used as the source.
As far as the output coil, it wraps around the rotating armature and primary rotor coil. So the armature slots must be big enough to fit 2 sets of wires in them. This is why I am using a pretty large motor (treadmill 1.6HP permanent magnet one).
If you look at the patent Figure 1 for simplicity, the commutator for the primary coil is labeled as 12, and the Sliprings for the output coil is labeled as 13. Both those coils wrap the same rotor armature, in the same slots. Adding sliprings becomes necessary to get the AC output off the rotating shaft.
This all means the build is a little complicated, because most (if not all) motors do not leave room between the bearings to install slip rings and brushes. So unless you have a hollow shaft, this means you are redesigning the motor housing , endbells, brushes, etc.
Currently I have the commutator end ready and it fits into the existing endbell with the stock brushes. I am now working on the sliprings. Once those are done, I will have to redesign an extended endbell for the slipring side that can accommodate the output brushes. I really want to do it in that fashion because I want to reuse the existing magnets and housing, because the arc magnets in this thing are monster's and I probably can not match the precision if I used different field magnets and mounts.
Here's a pic of the inside of the housing
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Another thing that may have relevance in the Russian replications (
https://www.youtube.com/@electricity52nn89 )
It appears his builds 1,2 and 4 are using 12 slot armatures. And build 3 (the most successful build) seems to be either a 22 or 24 pole armature.
Greater number of slots results in finer grained rotation, or higher resolution rotation. But that's not the only way to smooth rotation. The slot span (overlap) per coil also contributes to smoothness.
But when determining how many slots to span per overlapping coil, you should also take into account the size of the field magnets. Just like a generator, optimal magnet to coil size and spacing matters. If you make the coil much larger than the magnet, you end up with a dead zone while passing the middle. Make the coils too small compared to the magnet you probably retain the sinusoidal waveform but lose much of the available power.
Best option IMO is fit the armature into the housing, mark the armature where the magnets start and end, they you can get a good idea of the proper slot-span per coil.
May need to look into old winches! Those suckers have 4 field poles (some have magnets, others have coils) , 4 brushes and are beasts. Remove the gearing and they can spin thousands of RPM.
Some winch armatures use a single thick loop winding, while others use multi-strand.
Not sure which kinds are best, but it may be a viable outlet for this project
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Nice, look at this..
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I found a tead-down video, and here are the guts..
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We have a really cool 16 pole flat commutator, 4 brushes, 4 permanent magnets, and the armature looks pretty beefy.
The patent mention's using 4 brushes and 4 field poles, as this will double the frequency.
For $54 bucks, I may just jump on it and start fresh..