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1000000 RPM magnet video - would like the schematic!

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applicanon:
I saw a video a few years ago which was quite impressive, and I would like to duplicate the results.  The video was of a fairly simple circuit which utilized a hall effect sensor, a coil, a mosfet, and various neodymium magnets.  When the circuit was operating, it pulsed the coil at high frequency, causing the magnet to rotate at extremely high RPM.  The coil pulses were triggered by the hall effect sensor which was in turn triggered by the rotating magnet.

The video shows a super simplified version of the circuit, but I would like to have a schematic complete with part numbers etc. which would allow me to simply build it myself without any trial and failure.  If anyone out there can help me with this I would very much appreciate it, as would many others, as I'm sure it will be a popular project for people to put together.

Last but not least, the link to the video!

applicanon:
OK so it turns out the schematic is available on the guys website!    :-DD

I don't really understand some of the things on the drawing, however..  Can anyone fill me in on what the item is which is labelled "BP" / "BP2"??  I'm guessing it may be a push button??  If it is a button, why 4 terminals?  Is it normally open or normally closed?  Is it not a button at all??

I'm assuming the coil gets connected between terminals "BB1" and "BB2".

The hall effect sensor connection points are easy enough to interpret.

Hope someone else thinks this would be a fun project too and will join me on this build!

T3sl4co1l:
"BP", looks like "Bush Putton". :-DD

Or "Button, Push" may be more grammatically correct in their original language (French?).

Seems the purpose is to pulse the circuit just to give an initial kick.

Q2 and Q3 appear to be swapped and reversed.  I think they are intended to be a complementary emitter follower, to drive the gate; as shown they would just short out the supply, not very fun.  R4 isn't really needed and can be removed (shorted out).

Note that the loop between Q4, D3 and C3 must be short; place them close together.

Beware that the output transistor is unlimited in current, and is dumping all the reactive (magnetic) energy from the inductor into a diode, which is shorting out the inductor half the time, which won't do any favors for discharging said magnetic field.  It may be better to place a TVS in series with D3, though it will probably get rather hot rather fast.  Better still, dump the energy into a capacitor (making a boost circuit), then dissipate the energy more gradually with a power resistor (discharging the capacitor's excess charge into the supply).

The next best thing is switching both the top and bottom of the coil at the same time (called a two-switch flyback converter), but this requires more hardware to pull off, so I won't try to list all the changes that would need..

The concern is that, if you expect real mechanical power out of this system (i.e., a few watts of friction is probably spent bouncing around that magnet), expect poor efficiency, say 10s of watts input.  A lot of which will be lost in the magnetic field, which is weakly coupled to the magnet on account of the air-core coil, the large distance between them and so on.  So the circuit will be a boost converter, first and foremost, with a quirky side-effect of also making a magnet spin.

Tim

capt bullshot:

--- Quote from: T3sl4co1l on December 05, 2019, 05:12:49 pm ---Q2 and Q3 appear to be swapped and reversed.  I think they are intended to be a complementary emitter follower, to drive the gate; as shown they would just short out the supply, not very fun.  R4 isn't really needed and can be removed (shorted out).

--- End quote ---
Though agreeing to the rest, I disagree here. To me it looks like it's intended the way it's drawn and is drawn correctly. Q2 and Q3 would be an inverting driver stage, R3 turns on Q3 when Q1 is off, R4 turns on Q2 when Q1 is on. Kind of unusual (not as one would expect) and maybe ugly, but should work.

RoGeorge:
Nice!   :D

That looks like the ideal setup to test if a magnet turned very fast would produce electromagnetic waves or not.  Turn the magnet, cut the power, then with a receiver look for any corresponding radio waves coming from the swirling magnet.

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