Self accelerating reed switch magnet spinner.

[MileHigh]

TK:

Something I have never seen and it puzzles me why no one has done it.  I figure the desire is to have a coil firing pulse with as sharp an edge as possible (in both directions) with full control over the pulse width and the starting angle relative to top-dead-center is what you want.  And you want to do it cheaply and easily and in the analog domain.

There must me a little $2 op-amp chip out there.   Power it from the source 12-volt battery.  I would have an independent pick up coil on a stand that you could move around.  So you fire the pulse from an alternate magnet on the rotor.  Your pick-up coil output connects to the + input of the op-amp and you have a 100K potentiometer to dial the voltage on the - input of the op-amp.  (Tie one side of the pick-up coil to a simple resistor voltage divider and a filtering cap at about +6 volts.)  The output from the op-amp is going to either be very close to ground or very close to +12 volts.  So you use that to fire your IGBT or MOSFET or transistor.  I would also run the op-amp output to a simple transistor voltage-follower to power a bright LED that strobes the rotor.  So you paint some white lines in the right places on the rotor and that's your rotary strobe to observe the pulse timing.  So you don't even need a scope.

So ultra clean fast switching and fully variable pulse timing to hunt for the sweet spot and throw in a strobe for free.  All this for less than $8.  Plus you can't forget the "exotic" pulse width control with a potentiometer.  A boss machine.

MileHigh

PS:  Perhaps instead of running off the source battery voltage you run the whole thing off a regulator chip at say 9 volts.  Just to stay away from the battery when the voltage output starts to choke.

[totoalas]

lo generator  in YT
he's using the ferrite rod as negative path instead of end of coil from positive source   and the induction of the coil closes the circuit
in his channel   where a reed switch simulation is shown also
totoalas

[forest]

Definately the sharp spike is one of the keys, and Tesla method of placing capacitor around the interrupter is the solution....but I'm having problems with capacitors, commonly used are not good enough because voltage rise too high and could damage them if switching time is not fast enough to lower tension (voltage) across them. But  I can say once in 2004 I accidentally combined the proper ingredients and got it working nice with 25V rated electrolytic cap in resonant circuit. Unbelievable....

[TinselKoala]

@Synchro:
thanks, yes, I think I also pointed out some time ago about biasing or tuning the reed switch with an external magnet on the other side from the actuating magnet (works with Hall sensors too)...

It is notoriously difficult to weigh magnets accurately. There are problems with just about every kind of weighing system that cause them to give inaccurate weights when you try to weigh a permanent magnet or working electromagnet. When you start adding rotation of parts or oscillating fields to the mix it becomes even more difficult. I'd need to see the _same_ degree of weight loss/gain from at least three _different_ weighing systems to be able to believe a weight gain/loss from a magnet system with moving parts. And then I'd need to construct a special apparatus or two to add yet other weighing methods for confirmation. I've done a few DePalma-type experiments myself, it was one of the things we were very interested in at a former employer's laboratory years ago.

@MileHigh:
I replied to your idea in another thread. I think it's a good one and I'll probably try it, if I can find the Bedini rotor in this pile of junk. At least I know where the op-amp chips are....

@Forest:
The cap to protect reed switch, relay, or motor commutator contacts should be a high-quality ceramic capacitor of high-voltage rating, 1 kV or better, with a low capacitance value (best found by experimentation.) It should be located as close as possible to the reed contacts themselves to minimize inductance in the cap wiring.
A good reed switch is a relatively expensive component, and all reed switches have limited lifetimes. They aren't really designed for switching inductive loads at high frequencies directly. Using a reed to switch a fast mosfet's gate voltage, letting the mosfet do the heavy lifting, is better for the reed's longevity but then you lose the "magic" of the noisy, jittery, contact-burning arcing reed.

[synchro1]

@Tinselkoala,


                    I think your new op amp test motor would be a strong contender for RWG's pulse motor build off prize this year. I'm looking forward to seeing your new design perform.