Self accelerating reed switch magnet spinner.

[TinselKoala]

Yep.

I particularly like the fact that a starting spin is not needed, and that it will run in either direction and still make all the spike and HV action you could desire. Also the strobe LED is really a neat feature. It allows tuning to the sweet spot instantly.

[synchro1]

@TK,


       The computer generated design file can be emailed to professional 3D printer outfits, there are a handful, who print on the most sophisticated printers. The choice of materials includes a variety of metals. They make castings from the 3D molds. Try and catch up with the process simply by typing 3D printer in the google search engine, and spending a half hour in study. I'll go ahead with my project independently, then after testing and uploading a video, you'll be free to download and email the design file to the printer site of your choice. Naturally, you are required to pay them, then they express mail you the finished part. NASA is building internal rocket engine parts this way. You guys are invited to suggest magnet strengths if you want to, or anything else. Let me point out that the current design would allow us the versatility of selecting between two or four monopoles or a bipolar and staggered polarity of four.


       A compact and nearly frictionless high speed rotor of this size would only require a thread spool size power coil to reach top speed, and I believe also a sensor coil of the same dimension and Ohmic resistance would be best. My power coil was a series bifilar, not to resurrect the old vendeta, because it goes faster.

[conradelektro]

................
I also think the sense coil can be a lot smaller, but I don't have any small magnet wire, just lots of #27.
.................

@TK:

You could use the coil from a relay as a sense coil

http://www.overunity.com/13523/has-anyone-seen-lasersabers-new-motor-runs-on-1000uf-cap/msg363167/#msg363167,
http://www.overunity.com/13523/has-anyone-seen-lasersabers-new-motor-runs-on-1000uf-cap/msg363297/#msg363297

with or without the core. I  guess any relay would do. 24V or 48V relays have more wire and higher DC resistance.

It is a bit tricky to get the coil out of some relays. I do it with a hack saw, a drill and a file. The relay has to be held in a vice. The soldering posts should be left in place in order to avoid handling of the very thin wire.

The drilling is best done with a box column drill press while the relay is held in a machine vice. In most relays the coil core has to be drilled free on one side (usually from the base of the relay). But this could be done with a file.

Did you try "repulsion mode" with your set up?

Very nice sensing circuit and the TL082 is a very interesting and versatile OpAmp.

Greetings, Conrad

[TinselKoala]

@synchro: thanks, that's very generous of you.

@conrad: Yes, I've considered using a relay coil for the sense coil. I have a handful of little relays from TV sets that aren't much good to me because they are normally open SPST. I want to stay coreless for both coils though and I'm not sure about getting the core out of one of those coils. I may have to just unwind the wire and wind onto a different former with no metal core. Getting the coil out of the relay is not problem, it's getting the core out of the coil. It would be too nice to find that they used a slipon bobbin that just slips off the corepiece.

I haven't yet tried repulsion mode. I want to arrange for one or the other of the coils to be movable for timing first. Right now the thing is "by chance" timed well and will run very well in either direction. It is easier to start using the setpoint pot alone in the "wrong" direction but it reaches slightly greater final RPM in the "right" direction. I have the starting technique now, it's very easy to start just by turning the setpoint pot properly.

[TinselKoala]

New sense coil, made from a relay core. It took about half an hour with file, hacksaw and nippers to get it out and remove the core.

It produces a higher voltage peak (surprise surprise) and I'm still experimenting with mounting location.