Latest: No back torque generator.

[broli]

CA should do. Clean all surfaces, add some CA activator on one part, let it dry, have CA on the other part. Put them together, and there you go.

Can't you just use two barmagnets magnetized through thickness, snapped together in the ends so you get opposite polarity on both sides - like the disc you showed, and let the exsess vindings go outside in thin air instead along the edge of the round magnet? So only the parallell windings are going along the bar magnet. That should in theory do the very same thing.

Vidar

You can use barmagnets as illustrated on the first page. Just make sure you understand why certain things are done the way they are.

I gave up on on building big magnet out of small ones. Since I have one single bar magnet laying around I'm going to attempt a new setup. Something like you can see below.

[Low-Q]

You can use barmagnets as illustrated on the first page. Just make sure you understand why certain things are done the way they are.

I gave up on on building big magnet out of small ones. Since I have one single bar magnet laying around I'm going to attempt a new setup. Something like you can see below.

That is exactly what I had in mind except you show only the half part of it and you use a rectangular coil.
I'll have two barmagnets but turn the other half so south is facing up - and the windings will go in the same direction over both barmagnets. The part of the winding that is in air I guess must follow the a half circle so it will not be affected by the magnetic flux. More like a D-shaped coil. I have all parts needed to build it so I'll try to se what happens when I fire it up.

Vidar

[broli]

I don't think you'll see any LED light with the size of your magnets. The length of the conductor over the magnet is the most important one. Make a brush and collector and have a multimeter ready.

[TinselKoala]

3M Super Weatherstrip Adhesive (also Permatex brand). Commonly called "yellow snot glue". It's a rubber cement type adhesive, slightly flexible when cured, so your magnets won't come spalling off at high speeds like with CA or epoxy. Available at big-box car parts stores. Don't get the black kind, it is not nearly as good as the yellow.
It is also the only adhesive I've found that will reliably glue Velcro to almost anything solid. And it's a lot faster than Gorilla Glue (which is really good for permanent bonds, once you get used to the swell factor).

[TinselKoala]

I don't think you'll see any LED light with the size of your magnets. The length of the conductor over the magnet is the most important one. Make a brush and collector and have a multimeter ready.

Even a big fast homopolar generator will only produce a small voltage--lots of current, but the least resistance will kill it. ( V=IR, so if V is small, R must be small too if you want much I) Since most LEDs have fwd voltages of 1.2 volts or more, you might have to get up to ridiculous speeds in a small generator to overcome even that tiny barrier...better put a whole JouleThief on there, it will light up a blue  LED with as low as 0.38 volts.
If it's even possible at all, that is.