The Following 8 Users Say Thank You to scibuster For This Useful Post:
Aianawa (11th November 2015), Aragorn (10th November 2015), Elen (10th November 2015), JATUS (12th November 2015), jimmer (11th November 2015), Joanna (11th November 2015), lcam88 (10th November 2015), reno (11th November 2015)
I think looking at the physics of an electric motor is very important when examining these machines. Electro-magnetism specifically.
If you examine an electrical motor without deciding whether it's function should be to generate current from movement, or to generate movement from current, then suddenly optimizations about the design of the device become evident even as we may discriminate one function over the other.
Motion in the rotor can be a result of an attractive magnetic force (N + S) and/or opposing forces (N - N). Most modern motors use the opposing forces to create rotor motion. An engineering decision was made at some point regarding this norm and it seems very view engineers revisit the issue. Most motors that exhibit over-unity type net output that I know of utilize attractive (N + S) force as the genesis of motion.
As long as the law of thermodynamics is true, the electrical energy from the collapse of a magnetic field should be equivalent to the energy required to lift the field.
Because the current and voltage associated with the event of a magnetic field collapse creates a instantaneous voltage peak, a type of transient spike wave form when charted. Capturing the electrical energy released from the collapse event is done by adding a battery or at least a capacitor setup to the circuit.
Lastly, current is not "consumed" in an electric motor in a way that can accurately describe it as being directly transformed into rotor movement. Normally electrical energy is lost (or dissipated) in two ways, 1) by ignoring or grounding electrical coils during the collapse of magnetic fields, 2) electrical energy can be canceled by a back-emf voltage produced by rotor motion (in the opposing force designs (N - N)). This happens when we see forget to observe a spinning rotor performing the role of the electric generator simultaneously. The generator function produces a voltage in the copper coils that works against the voltage introduced to drive the motor, this back-emf has a voltage proportional to rotor speed. 3) heat due to mechanical friction and electrical resistance.
For a given input voltage, when a DC motor (under no load) reaches its peak speed it can be said that the two voltages (input voltage vs back-emf voltage) are equal (± electrical resistance and mechanical drag). Ie neither the motor and generator functions of the device are visibly dominant.
So... the question I now pose:
Can an attractive force motor design (N + S) utilize the back-emf rotor generator function to further build on input voltage, rather than cancel it?
Does that help?
Last edited by lcam88, 11th November 2015 at 00:22.
for this long philosphical treatise about the EMK.
(Elektro Motorische Kraft)
But I'm pondering about those 50 000 little youtube motors which
some tricksers build with the help of David Copperfield.
And try to find more short ideas of my given youtube example:
1.battery, 2.wind, 3.solar cell, .... and more.
Maybe in my next dream I will see the fourth version.
I will say five things specifically about the device in the video you posted.
1. The bolts that hold the coils down could seem to be sharing space with batteries (if batteries are indeed a part). But a sheered bolt will be magnetically deficient and possibly could compromise functionality. Furthermore, the lever position control would be useless in controlling DC current pulsations required in a battery powered version in this configuration.
2. As the rotor approaches the coil, voltage induced into the coil that will further power the device. The field is strongest just as the magnet on the rotor reaches to top of the coil. Then the field has a moment of stillness when it collapses. Whether this field qualifies as an attractive moment (S + N) on the rotor is unclear to me. I suspect it does not.
3. The LEDs on either side that we can see blinking are primarily there to provide an R factor (electrical resistance) in the electrical circuit. If you remove them, the device it will not work. I suspect they define how the energy in the field collapse is dimensioned. Power = Amperage * Voltage => An R factor primarily limits amperage and as soon as that is defined, the nominal voltage too is then defined.
4. It is not exactly clear to me how the lever apparatus functions. It may be a type of magnetic timing device that performs its function when within a field (of a coil) with a certain strength... Perhaps it is also a part of the circuit that provides capacitance (if that is indeed a capacitor soldered in there) for capturing energy from the field collapse event. That energy is then be fed back into the coils for a moment of opposing force (N-N) rotor impulse.
5. The rotor (considering a still air environment) is mostly unloaded. The entire work load of the device is defined by air resistance of the rotor as it passes through the air, as such I consider the design decisions behind the device to be focused on demonstrating the principles at work.
Last edited by lcam88, 11th November 2015 at 13:27.
(brushless DC Motor electronic commutation)
with an Atmel microprocessor ATtiny13-8-SOIC 8-pins (includes some commutation Software) and a flat little
battery on a flex-board in the middle of the lever switch.
Do you see that the lever switch is a pancake construction where between the thin flexible board is.
(But all electronics can also be inside the coils
and the pancake is the battery or better it's a little akkumulator and the pancake is a solar cell.
So when you put the device into the dark it will run anyway for 24 hours before stopping.)
I think that is light years away from David Copperfields understanding of electronics today so we didn't need his help.
Last edited by scibuster, 11th November 2015 at 13:28.
DC brushless setups normally requires a rotor position sensor. The sensor signal needs to be fed into the processor so that coil modulation can be calculated.
In some simplified setups, the sensor is not used, but then the processor must "presume" rotor position. It does that by following a startup sequence where it slowly starts, allowing the rotor to fall into sync, then it accelerates to nominal speed and off it goes. If the torque ever exceeds the nominal load the motor is rated for then a failsafe is required...
This motor is started by hand, an external impulse... how does the processor then know the device has started and sync with it?
Modulation of the coil requires a switching solution so that DC current can be "timed" with the passing of the rotor (rotor position sensor issue presumed here). That can be a simple transistor MOSFET device, do you see evidence of that?
There is a BLDC sensorless mode possible.
Same as used in propeller model airplanes.
This motor has very little torque when it starts and also less torque when in running mode.
So sensorless mode is the best ideal mode for this model.
It's a 2-phase sensorless but because of such less torque that this type is never used
in little hobby BLDC motor airplanes.
Ok it is possible. But I am not familiar with package dimensions of the IC to suppose it could easily fit in the "pancake" thing. And I can't see any evidence of the transistor used to modulate the current.
It would seem that in your model, the controller "pancake" is only used to house the IC, and that its apparent function to control the motor is faked also. That leaves you with a small burden to address, how does the positioning of the "pancake" control the motor speed?
It seems like a lot of trouble to fake something that can easily be done properly...
Also this configuration as shown in the vid, doesn't require two phases. You could use a single phase in parallel... as it appears to be wired.
You might leave a message on the video and simply ask:
1. unbolt the left copper coil (more wire on the left side) to verify the construction inside.
2. dismount the lever from the rotor support and pry open the lever to verify if there are any IC's inside.
I doubt an authentic device holder would have a problem doing that. I also understand the principles such an authentic device are based on and as far as I can see, your idea about a battery and elaborate semiconductors driving the motor, while possible, seems to be the more remote possibility.