This project uses an UNO + DC motor shield + laser + a coil of copper wire.
The field reverses (7 Hz) causing the spin in the electrons in some ferrite beads to flip, rocking a pendulum, deflecting a laser seen as a red stripe (if this uploads)
The ferrite bead rotates along the axis of the field lines.
It is called the “Einstein de Hass” effect. [https://en.wikipedia.org/wiki/Einstein–de_Haas_effect](http://Wikipedia article)
There are engineering details about how to make a High Q oscillator that is not effected by stray fields.
I can assist people wanting to make one, they will be most valued by Physics Lecturers.
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Cool project Peter!
I was surprised to have anyone read, thanks, these details may help or be of interest.
This is the wiring of the shield, 12 V 1 A in. There is a better cheaper board with 4 A through heat sinking
As the Q of the pendulum (hybrid balanced gravity and torsion) goes > 300 delayMicrosecond allow the resonance to be found. Other operations like serial print appear to affect the timing so I have not been able to automate frequency scan and lock. Q = resonant frequency / half width bandwidth or 4.53 x rings to 50 % power.
This shows the ferrite beads (glued as they are not conducting) that rock around the axis of the field lines. I am ordering Other beads of potentially better specs from the US and at 10 c each have too many. Anyone is welcome to them.
It is built on a bath tile placed on a $5 rotary spice tray. The former as a much cheaper optical table, the latter demonstrates it is not sensitive to the earth’s magnetic fields.
It is not ready for formal scientific publication until a hall probe measures the magnetic field on the surface of the ferrite. This tells us how many electrons have flipped their magnetic field. While okay for a Uni lecture it is not enough to say it must be this. I hope that makes sense.
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Hi Peter,
Still a very cool setup. I’m sure you could incorporate a hall sensor or a magnetometer in a way that would be beneficial.
If you are running an ultra time sensitive operation it is good to comment out your serial print lines in the code. You will find that each line printed takes about 200us to send. I think that this runs in parallel though, as to not slow down the rest of your code. It’s still worth a shot!
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Thanks Stephen,
The thinking (not my own but that of the science community) is that electrons are tiny magnets. Delving into the quantum physics it is pure magnetic field but no current. Further the electron has the property of a flywheel, angular momentum, but does not physically spin (ie so many revolutions per second). We have to be diplomatic here as so many teachers think differently and appear stuck. Perhaps this demo will help. There is real distress here that this is electronics in an insulator.
Because we are saying the electrons are little compass needles with flywheels (you can understand the first paragraph now) we need to measure the number of electrons that flip and tally this with the amount of rock this gives. Now the surprise is that there is twice as much magnetic field generated by the electrons is a factor of 2 bigger as the electron takes 720 degrees to do a 360 rotation.
At any rate the plan is to glue hall sensors, may be magnetometers onto a dummy sample. Hence the modular design in the next iteration. Einstein and de Haas an really every one else had a pick up coil to measure field, but now we have microsecond field flip that would be a nightmare.
Also necessary is to measure the rotational kick which involves measuring the Q of the pendulum and thus my frustration that the program I wrote didn’t work. It is also necessary to measure the spring back for say a 10 degree deflection. To do this you might place different masses on the pendulum and then rotate the rig by 15 degrees and see the relative defection.
ESP32 has 12 bit ADC which puts it clear or the Arduino I think. I started with a 555 in late January so I have really no experience with Arduino. I discovered shields when I bought the the motor shield and said to myself why would anyone put in those dumb down pins. It is one tough learning curve, mate!
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I am fascinated by this project…I would love to see some pictures of the laser beam in a mist or smoke haze.
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This a night shot would be better, but it is a good idea as you can see the path of the beams.
Thanks.
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Thats insane 
what do you think the sustained angle of deflection is?
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Central beam 95% travels straight through as I don’t have a light mirror only cut overhead projector transparency. There is a trick to sticking it on the oscillator.
It then deflects it 100 ° and it oscillates ± 2 ° but take about 100 excursions to reach this.
The overhead transparency screen intercepts the beam at 20 ° giving the impression of a beam x 10 sitting in space.
The smoke was from a smoke machine.
Hope it all helps.
Thanks for the interest. Pete
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The unit is now smaller with $5 1000 turn solenoids from a magnetic levitation product ( the coils are sold separately)
I must admit I find C++ Arduino easier to make mistakes with but now I ramp through the frequency of oscillation 1 micro second at time.
This gets the unit on beat, it has a window of 0.2 milliseconds and a Q of 400.
I have to get a sequin from Spotlight as a good laser mirror and then I think the unit is ready to roadshow to the education department.
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