Fast oscillating electromagnets

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Averagea
 
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Fast oscillating electromagnets

Post by Averagea »

I’m protyping an idea where electromagnets make different steel objects resonate at their resonant frequencies between 20-1600 Hz for 1-5 seconds. I already have most of the parts from Adafruit, but before buying the rest I just want to make sure I’m not missing something?

I’m planning to control 4 electromagnets ( https://www.adafruit.com/product/3872 ) with Arduino Uno and Motor Shield v2.3 instead of DC motors.

Then I control the oscillation of the electromagnets with values coming from potentiometer and setSpeed(), Delay() and delayMicroseconds().

Questions:

- Does the above sound doable and logical?
- Can I also change the polarity of electromagnet with run(FORWARD/BACKWARD) ?
- Is there some things to watch out when powering these on/off or changing polarity this fast?
- Would 12V 2A power supply be enough or should I have a bigger one?

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adafruit_support_bill
 
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Re: Fast oscillating electromagnets

Post by adafruit_support_bill »

Using the MotorShield, you can reverse the flow of current which will reverse the polarity of the magnetic field generated by the electromagnet. 4 of the magnets will draw a little over 2A at 12v if all energized at the same time. So a 12v @ 2A supply is marginal.

Some other issues I see are:
1) reversing the polarity will not cause a magnet to repel a steel object - unless that object is also magnetized.
2) The inductance of the electromagnet will resist the change in current flow, so you may have trouble achieving the higher frequencies.
3) The i2c communication speed with the shield may also limit the maximum attainable frequency - particularly if you are trying to do multiple magnets at the same time. You could avoid that limitation using TB6612 breakouts instead of the shield. That requires more pins for control, but it eliminates the i2c communication overhead. https://www.adafruit.com/product/2448

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Averagea
 
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Re: Fast oscillating electromagnets

Post by Averagea »

Thank you for quick and detailed answer!

I’ll go with the TB6612 breakouts if higher frequencies will be a problem and make sure the power supply is enough. I will first try achieving the resonance without reversing polarity. If not successful then I’ll add small magnets to steel objects and try pushing and pulling.

Here is something similar related to creating resonance with aluminium tubes, magnets and electromagnets for anyone interested: https://blogs.wcode.org/2013/08/solar-w ... and-x-osc/

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