Old 10-27-18, 06:26 PM
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Originally Posted by Jmclay View Post
Thanks Steve! My hope was that by laying my (admittedly lengthy) thought process and course of action out, it would help others and speed all of us towards improvements figured out by others. I'm happy to answer questions or further explain how I went about this exercise, on the list.
There are a number of aspects of the problem that intrigue me, but perhaps the biggest is why so many folks don't think a carbon brush would work. I've had the fun of taking apart motors at work and at home and have been impressed at the design of the carbon brush assemblies in motors. Some of these motors are windshield wipers, some were vacuum cleaners, etc. The wiper motors ran on either 12V or 24V (don't recall) and probably drew an amp or so. I imagine the vacuum cleaner motor was closer to 20 or 30 watts(??), so was well under an amp.

Considering the speed of the armatures, the brushes must have traveled quite a long distance over the contacts on the armature (what are those contacts called?). Seems like it would be a much more demanding application than steerer tube brush, but how often do they wear out? I can't remember having one fail.

I will admit that most of these brushes would likely be too large to mount in a steerer tube, if only due to the large hole that would need to be created in the tube. A lot of these brush assemblies were pretty long too, so possibly difficult to insert into the down tube??

The odds of me ever trying to fabricate any of this stuff is incredibly small, but I can't help but ponder the technical aspects of other ways of getting the power transferred using other means. Everything seems to have pretty severe shortcomings. I ran some numbers on how to use differential capacitance to couple the power, but the available capacitance is so small that it would have to be driven with an AC waveform that was into the gigahertz range. Definitely not practical!
Using magnetic fields didn't seem practical either, especially with so much steel nearby to divert the magnetic field. I've got one idea that has a slim chance of working... not that it would be easy to prototype, though.
I've considered the idea of using light pipes and fiber optics to just send light across the barrier instead of electrons. I've got very little experience in this area, despite having taken a class on optical waveguides in semiconductor devices (needed it to finish my masters), but can foresee difficulties. Also, it's not especially friendly towards the hobbyist.

Anyway, it's one of those subjects that is pretty much wide open for tinkering and experimentation! Love it!

Steve in Peoria
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