The Thomas Motor

[k4zep]

A most interesting observation.  After peaking the motor with magnets getting it to run up to 5200 rpm at 19+VDC.  Questions what happens if we reverse the coils?  Most interesting.  Changing NOTHING but the wiring to the coils, in reverse polarity, up to 11.6 VDC it will run in reverse, above 11.6 VDC it will run normal direction. As you go away from that 11.6 VDC point and lower, it speeds up more, there is more torque away from that point.  Same for going above the 11.6 VDC.   Current is very high, about 150 to 160 ma which is to be expected.  Out of sheer luck and a lot of experimentation I have found the sweet spot where the fields from the core magnet and the polarity of the field in the core and the field from the rotor all comes together.  It is a very dynamic thing. I just realized it should work great with AC as a synchronous motor with magnetic enhancement  using 2 magnets side by side, pull in with a S magnet, push out with the N magnet, both enhanced with the polarized field from the windings..   Waiting for parts for the next motor.
Having fun.......

Respectfully
Ben

[TinselKoala]

Hi Ben and Gyula.

You might be interested in a couple more of my Orbette 1.0 vids. In this version of Orbette I used ferrite "beads" which are more like hollow cylinders than toroids, because those were all I could get at the time. I wound them toroidally with minimum turns, just one layer of wire. The original Orbette is not as nice as the 2.0 version but was made entirely without machine tooling.

In this first video you can see the core bias magnets, 4 small NdBFes, at the "far end", most distant from the rotor, of each core. I don't really talk about these magnets in this video and I can't seem to find the one where I specifically showed how they work and what they do. As you have also found, the bias magnets reduce the current necessary to drive the core to full saturation "transparency" and so they enhance the efficiency of the motor, by allowing higher RPMs for a given input power or by reducing the input needed for a given RPM.

http://www.youtube.com/watch?v=mi_FJwpPrQk

The second video is the first of a 4-part series explaining the Orbette 1.0, the three types of Pulse Motors, and I show the effect of current reversal to the coils in realtime, by using the Secret of DPDT, as well as timing points and other stuff.

http://www.youtube.com/watch?v=WfdLC676S94

I've also done some power dissipation videos showing how to determine the actual mechanical power of the rotor itself, so that can be compared to the electrical input power. One method uses a geometric calculation of the rotor's Moment of Inertia and a chart recorder to examine the slope of the rotor's unpowered rundown rpm vs. time data, and the other method uses a model airplane propeller with known power dissipation curve as a driven load.

[k4zep]

Thanks TK,

I feel I'm running way behind you and your research.  Thanks for the links to your videos, I'll give them a watch.
Lots to digest here!

Respectfully

Ben K4ZEP

[gyulasun]

Hi Ben,

Thanks again for the details, both to my questions and for your further observations. Regarding the 11.6V DC supply voltage as a "turning value" i.e. changing the direction of the rotation, I believe it is caused by the followings:
up to 11.6V (starting from  say 1-2 volts) there must be a supply voltage value at which the core goes into saturation already enough (but probably not fully) to let the core magnet do its job i.e. to give a (certain) repel kick to the rotor magnets. When the supply voltage increases towards the 11-12V level (this level is particular to your present setup of course), the magnetic field from the toroidal coil on the core just reaches a strength which already starts hampering the operation with the earlier pole polarities neded for that reverse direction run.
How can this happen? I think that under 11.7V the poles of the toroidal coil just remain mainly inside the toroidal volume, guided by the core and those poles are mainly close into each other, not influenced too much by the poles from the core magnet.
At the 11-12V level the poles of the coil must come out from the circle path and surely close onto the poles of the core magnet and if this is a 'twisted-out' flux path with respect to the earlier case,  then not only the kick is gone but an attract-back force may develop during the on time of the coil at that voltage level. This is why the wiring of the coil should be changed.
However, above the 11.7V and higher, if my above hypothesis is correct, then it is the input current level which may finally give the kick (i.e. fully saturates the core AND closes the flux path onto the core magnet) with a strength and pole polarity which is correct for the kick-out too.

Of course this is a hypothesis from me, I think it can explain what you found.

One more thing: there are cores with square shape B-H curves, I recall the Philips now Ferroxcube 3R1 material developed for magnetic amplifiers etc and Elnamagnetics or (Farnell in Europe) still stock it. This is a data sheet for it: http://www.ferroxcube.com/FerroxcubeCorporateReception/datasheet/3r1.pdf  and here is a 36mm OD toroidal core from that material: http://www.elnamagnetics.com/?s=tn36&type=spec  (TN36/23/15-3R1) I do not know their price but at Farnell it is about 11.5 Euro (a core with OD=23mm (TN23/14/7-3R1) costs about 2.6 Euro). I mention these because these cores need the lowest input power to bring them into saturation.

regards,  Gyula

[k4zep]

Hi Ben,

Thanks again for the details, both to my questions and for your further observations. Regarding the 11.6V DC supply voltage as a "turning value" i.e. changing the direction of the rotation, I believe it is caused by the followings:
up to 11.6V (starting from  say 1-2 volts) there must be a supply voltage value at which the core goes into saturation already enough (but probably not fully) to let the core magnet do its job i.e. to give a (certain) repel kick to the rotor magnets. When the supply voltage increases towards the 11-12V level (this level is particular to your present setup of course), the magnetic field from the toroidal coil on the core just reaches a strength which already starts hampering the operation with the earlier pole polarities neded for that reverse direction run.
How can this happen? I think that under 11.7V the poles of the toroidal coil just remain mainly inside the toroidal volume, guided by the core and those poles are mainly close into each other, not influenced too much by the poles from the core magnet.
At the 11-12V level the poles of the coil must come out from the circle path and surely close onto the poles of the core magnet and if this is a 'twisted-out' flux path with respect to the earlier case,  then not only the kick is gone but an attract-back force may develop during the on time of the coil at that voltage level. This is why the wiring of the coil should be changed.
However, above the 11.7V and higher, if my above hypothesis is correct, then it is the input current level which may finally give the kick (i.e. fully saturates the core AND closes the flux path onto the core magnet) with a strength and pole polarity which is correct for the kick-out too.

Of course this is a hypothesis from me, I think it can explain what you found.

One more thing: there are cores with square shape B-H curves, I recall the Philips now Ferroxcube 3R1 material developed for magnetic amplifiers etc and Elnamagnetics or (Farnell in Europe) still stock it. This is a data sheet for it: http://www.ferroxcube.com/FerroxcubeCorporateReception/datasheet/3r1.pdf  and here is a 36mm OD toroidal core from that material: http://www.elnamagnetics.com/?s=tn36&type=spec  (TN36/23/15-3R1) I do not know their price but at Farnell it is about 11.5 Euro (a core with OD=23mm (TN23/14/7-3R1) costs about 2.6 Euro). I mention these because these cores need the lowest input power to bring them into saturation.

regards,  Gyula

Good Morning Gyula,

Up early, thinking. 

I think your evaluation is right on or at least it works for me.  Thanks for the heads up on the core material, It's been a couple years since I bought my cores, I'll look into them.  I really need a bit smaller cores (harder to wind!).  Right now I'm trying to put enough winds of #38 on them to make them about 16 ohms.  Time consuming. The new motor I'm working on needs a lot of cores......so back to it after I finish my coffee.

Ben