Confirming the Delayed Lenz Effect

[conradelektro]

Progress:

By moving the coil further away from the ring magnet I could increase the speed.

12 V -->  18 mA , ~ 0.22 Watt,    84 Hz (~ 5000 rpm)

15 V -->  21 mA,  ~ 0.32 Watt,  110 Hz (~ 6600 rpm)

18 V -->  23 mA,  ,  ~ 0.42 Watt,  121 Hz (~ 7200 rpm)

An other hole is needed in the base plate in order to move the coil even further away. Has to wait till tomorrow.

Good night, Conrad

[conradelektro]

@Farmhand: Thank you for the explanation. I will take that into consideration.

What is your opinion about pancake coils or a stack of pancake coils as a pick up or generator coil? Would that may be exhibit some interesting strangeness?

I just like to build little motors that spin rapidly (must be the child in me). My knowledge of electronics is very little, therefore I am not really expecting to discover OU. It is just a hobby.

Greetings, Conrad

[DeepCut]

@Farmhand: Thank you for the explanation. I will take that into consideration.

What is your opinion about pancake coils or a stack of pancake coils as a pick up or generator coil? Would that may be exhibit some interesting strangeness?

I just like to build little motors that spin rapidly (must be the child in me). My knowledge of electronics is very little, therefore I am not really expecting to discover OU. It is just a hobby.

Greetings, Conrad

Nice build Conrad

Even if i multiply your RPM by 10 to be around my 40KRPM, you would still be using a lot less power than my setup.


All the best,

DC.

[gyulasun]

Hi Conrad,

Here are some p-channel MOSFET types, I used Farnell but if you have a local cheaper source for those types, you could order from it of course. By the way, I think at least a 3-5 Amper drain current rated type is to be preffered versus the only 1A or so types because in case you lower the coils DC resistance, you do not have to change the MOSFETs. I think that even the 40-80 Ohm relay coils still cause losses but at least they are ready made and you do not have to wind them for the tests. Another factor is the drain-source voltage rating due to the voltage spikes at the coils switch-off times, even the 100V ratings may be a bad choice, at least the 200V rating is preferred, albeit the two MOSFETs are in series from the coil point of view, so their voltage ratings also add up.
http://uk.farnell.com/international-rectifier/irf9630pbf/transistor-mosfet-polarity-p/dp/1653665 (200V/6.5A 0.8 Ohm)
http://uk.farnell.com/infineon/spd04p10pl-g/mosfet-p-ch-100v-4-2a-to252-3/dp/2212868   (100V/4.2A 0.55 Ohm)
http://uk.farnell.com/diodes-inc/zxmp10a18ktc/mosfet-p-ch-100v-3-8a-dpak/dp/1843773RL  (100V/3.8A 0.15 Ohm)

"Horse shoe + two drive coils + two Hall sensors, where does the generator coil go?"

Well, the simplest (perhaps) would be to use a longer shaft (or two shafts in line tied together, this would involve one more ball bearing at least) on which two ring magnets could be fixed: one is for the motor, the other is for the generator. More about this tomorrow.




Hi Deepcut,

The explanation is coil inductive reactance, that is which limits your output power. To understand this better, you have an 1.2 Henry coil (when aircored) with a 166 Ohm DC wire resistance. This gives a 2Pi*f*L inductive reactance, f is the frequency depending on the RPM. Say, with 600 Hz, this gives 6.28*600*1.2=4520 Ohm.  With a core, this is rougly 4 times as many, cca 18 kOhm.
So your coil behaves as a generator with an unloaded output voltage, 120V when rectified and unfiltered, and which has at least a 4.5 kOhm inner impedance. If you connect a 10 Ohm, 100 Ohm resistor across this coil, then you have a voltage divider whereby the AC equivalent of the DC 120V feeds at least a 4.5 kOhm coil impedance and the load resistor in series, what remains across the load is very low, allmost all the induced power  is wasted in the coil. 
You may use a step down transformer directly at the coil output but off the shelf mains transformers made for 50 Hz mains frequency may introduce losses at the 400-600 Hz frequency range.
Another possibility is to tune out the inductive reactance with an identical capacitive reactance and there remains the coil winding resistance which will give the generator output resistance, 166 Ohm but this would be valid at and near to a single RPM frequency.

Gyula

[DeepCut]

Thanks Gyula, that makes it all clear.

And thanks FarmHand, food for thought.


All the best,

DC.