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Forum: µC & Digital Electronics Foucault pendulum with drive by an electromagnet used as a clock


Author: Jeremias (Guest)
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Hey guys,

I started with a new project.
As the titel already says, it should be a Foucault pendulum
(https://en.m.wikipedia.org/wiki/Foucault_pendulum)
and it should be much smaller than normal.
But because of the fact, that a smaller pendulum means that the
duration of the swing is much shorter, I now wanted to accelerate it by 
using an electromagnet.
To control this, I will use an Arduino Uno Board.
This will be no problem for me and others have done this before.
But I also want to read out the angle of the swing to convert it into a 
time.
I now wanted to ask you, if you know a trick or a sensor with which I 
can read out the angle
with as less sensors and the most precision as possible.

Can you please help me?


Greetings,

Jeremias

Author: Phil (Guest)
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First of all: Electric Parts may be cheap but on the other hand it costs 
more engineering - so you should declare whats cheap for you ;-)

My ideas:

Built a gyroscope into bowl.
- Needs wire or wireless solution (weight may manipulate bowl)

Use a cheap Webcam or CCD Chip and Analyse image
- You won't get this to work without an ARM an you need lots of Math

Using photo sensors
-You need a lot of them and light from above. Therefore it's cheap 
solution

Hall Sensor / Magnetic field detection
-May work if you have a metal bowl. But difficult to determine direction 
and angle cause you have to create / calibrate correlation between Field 
/ Angle (Math again)

-Put a pin at the bowl and build a capacitive detection plate


You can also try a vertical solution with components above. But even 
there you have a continuous error rate in measurement to interpolate

Author: clockwork one (Guest)
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Put a mirror onto the bottom of the mass of the Pendulum. Place optical 
sensors (or camera)under the pendulum which evaluate the direction of 
movement by the reflections of the mirror. The optical sensors can also 
be used to switch on the drive of the pendulum.

Take as inductive sensor the stator of a 3-Phase motor. By comparing the 
voltages in the 3 phases you can evaluate the direction of movement.

Be simple: take a quartz driven clock. Compare its secondpulses with the 
pulses of the pendulum-drive. Adjust by the phase-difference the length 
of the pendulum synchronizing by this way the crystal clock and the 
pendulum.

Author: restfet (Guest)
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Phil wrote:
> Built a gyroscope into bowl.
> - Needs wire or wireless solution (weight may manipulate bowl)
>
> Use a cheap Webcam or CCD Chip and Analyse image
> - You won't get this to work without an ARM an you need lots of Math

Why not go the direct way and use an electronic MEMS gyroscope?

Author: Joe F. (easylife)
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A 2-axis force sensor at the pendulum's gimbal might work.
Could be built using 2 piezo elements.

Author: Jeremias (Guest)
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Thanks guys, your answers helped me really much.
I will think about them and try to find out the one that works best.
If I found anything out, I will inform you.


Greetings,

Jeremias

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