Confirming the Delayed Lenz Effect

[TinselKoala]

@Conrad: Why in the world are you using a P-channel mosfet in that circuit? The equivalent or even better rated N-channel mosfet would be cheaper and more "logical" in that single-transistor "high side switch" circuit, wouldn't it?

[Jack Noskills]

I did an experiment few years back and got some results of which I don't understand. There seem to be motor guys here so I will try to explain it, maybe it is usefull to someone.

I put two strong neodiym magnets on a flat disk, both faced the same way 180 degrees apart. This disk was placed on a rod which was connected to electric drill. Drill had trigger based power control, I press little and the motor spins little, I press hard and motor spins faster. Next I put lots on neodium magnets in a tube, two sets of magnets. One set all S faced and the other set all N faced. There was a slit between the magnets where the disk could rotate.

I placed the disk so that all magnets were repelling all the time: tube S - S N - N tube. So it was difficult to hold there. Then I started the drill. It had a hard time rotating the disk at lower speed. I gradually increased the rpm's and I could hear the motor doing lots of work because the magnets were so strong. But after a certain level of rpm was reached the motor sound dropped significantly and disk accelerated. As if the magnets were repelled more when magnet in the disk was moving out from the tube than when it was coming in.
Is this normal ? Is this the same as delayed lenz effect using magnets only ?

What if there would be electromagnets added on the sides of the tube, at the end of core right next to slit where disk rotates ? They would create reverse polarity and if they would be equal in power as the tube magnet the net force seen by the disk would be nullified. Disk would then rotate without drag generating power to coils.

[synchro1]

@Jack Noskills,

                      Can you upload a sketch?   

[conradelektro]

@Conrad: Why in the world are you using a P-channel mosfet in that circuit? The equivalent or even better rated N-channel mosfet would be cheaper and more "logical" in that single-transistor "high side switch" circuit, wouldn't it?

@TinslKoala: the P-channel MOSFET is used because the Hall sensor A1101 is South Pole sensitive and switches from High to Low.

http://www.allegromicro.com/~/media/Files/Datasheets/A110x-Datasheet.ashx

From the data sheet: The output of these devices switches low (turns on) when a magnetic field (south polarity) perpendicular to the Hall element
exceeds the operate point threshold, BOP. After turn-on, the output is capable of sinking 25 mA and the output voltage is VOUT(SAT). When the magnetic field is reduced below the release point, BRP , the device output goes high (turns off). The difference in the magnetic operate and release points is the hysteresis, Bhys, of the device. This built-in hysteresis allows clean switching of the output, even in the presence of external mechanical vibration and electrical noise.

One could have used an other Hall sensor which switches from Low to High or a second transistor in between.

I will use the equivalent N-channel with a trigger coil in my next test coming soon.

Greetings, Conrad

[Farmhand]

Hey Farmhand

The output from a field collapse in voltage depends on if there is a load to capture it, and  how heavy the load is. Unloaded 12v could produce 90v during collapse. But if you use a snubber diode across the coil to feed the collapse back into the coil, there wont be a higher voltage and the collapse will happen slower than if just bipped into a cap or lighter loads. Set up a 12v relay for buzz mode and measure the peaks. Or touch the ends of the coil with wet fingers. Then if you put a capture diode to a resistor from the coil of the relay, depending on the resistor value, the peak voltage will differ.

Like in a switching supply. If there were no regulating of the output, say we disable regulation, the output would be quite high when the output cap is full with no load. Some use a resistor to always load the output a bit. Not just to self discharge the cap.

Mags

Well in my opinion using a snubber is not as good as discharging the inductive energy to a few volts above the supply voltage in most situations like pulse motors and such. I've done plenty of experiments that showed me this. Try a snubber diode on a Bedini, ie. use the energizer as normal to charge a second battery, then fit it with a snubber diode, take away the charge battery and start it up without adjusting anything, see what happens. In my experience the motor runs slower and requires a wider pulse width is less efficient and less powerful. Depending on what result you want or are happy with will depend on what you do.

I'm fairly sure I can clearly demonstrate the effect with the motor I am experimenting with now. Should I ?

Cheers