Help assembling Electromagnet Circuit

I am very inexperienced with electronic circuits and this is my first arduino project. I am having trouble with the schematics I am following for a project. [Magnet Levitation with Arduino - Arduino Project Hub]

The schematic shows two power supplies, but the parts list shows only 1. The schematics are represented differently in the fritzing diagram and the shield. I am not buying the premade shield and building this out on a breadboard. I am not understanding how to route a single power supply to both the electromagnet and the arduino.

Look at the circuit board image! It shows only a single connection for the power supply. So only one is needed. It connects to both the magnet and the Arduino. Very poor design, but it is what it is.

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Any recommended changes? I was planning a 12v 1A supply

What is meant in the Fritzing diagram by 5V ~ 12V?

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This worries me about the rest of the project.

Tom... :grinning: :+1: :coffee::australia:

You will have to explain why, I do not have the knowledge to understand. I know it is a working project. There is video of it working. This is just for a kids science project it is not mission critical hardware.

That means ANY voltage between 5 and 12 can be connected there. That is WRONG because the lower limit for the Arduino power on that pin is about 7 volts. Makes the rest of the project potentially have errors.

Maybe. :roll_eyes:

Ok, so I hooked everything up. I had an old wall power adapter that is 12v, 1A output that I used for the power supply. I just cut the wire and hooked it into the power rails on the breadboard. When I plug in, the led on the arduino lights up. I have not tested functionality yet. I noticed that the transistor was getting hot. I put a temp guage and it goes from 75 to 100 in about 10 seconds so I unplugged it. Transistor is rated to 5 A and 100V. I have the B terminal of TIP122 going to the brown side of resistor, C-terminal to the side of the diode without a line and E-terminal to ground. I am unsure if I have the diode configured properly on the breadboard. I have the diode between the leads of the electromagnet and the leads to positive rail/TIP122 C terminal(2 leads and 1 side of diode on each of two two terminal strips). Does it matter if all these are together on each terminal strip?

What have pins of the UNO have you got connected to the power rails of the breadboard?
I hope Vin and Gnd!!!!
What is the transistor part number?

Can you please post images of your project.

Draw a circuit diagram of your project, hand drawn, not a Fritzy.

Do you have a DMM?

Thanks.. Tom.. :grinning: :+1: :coffee: :australia:

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I noticed that I had pink lead of Hall Effect Sensor previously going to the ground rail. I moved to A1. Transistor still getting hot after move. Perhaps the switches? I drew in the bars that are on the backside that seem to indicate some kind of internal connection. The switches make adjustments to electromagnet. Notice how it is represented differently on the Fritz and the Shield? Is there a short?

I have a DMM. Vin and GND pins are connected to rails. Does it matter that I used two different GND?

What do you mean, the gnd of the Uno has to be connected to the gnd of the solenoid supply.

Tom... :grinning: :+1: :coffee: :australia:

I mean there are two GND on the Arduino and I utilize them both randomly. As shown on diagram I connect one of the GND of Arduino to common rail on breadboard. Are grounds all good on diagram?

Yes that is okay, the gnd pins on the Uno are connected together.

How much current does the electro-magnet draw?

Tom... :grinning: :+1: :coffee: :australia:

Electromagnet pulls 0.33A. I have not loaded the code onto the Arduino. The electromagnet is not activated at this point. The hall sensor needs to be 5 mm from the electromagnet and when it senses a magnetic field, it will send the signal to the Uno and the Uno will turn the electromagnet on and off thousands of times a second to keep the permanent magnet at a certain distance from the electromagnet.

Any other possibilities?

Links to technical information on the hardware devices helps. Posting a schematic would us help you solve your problem.

Maybe and maybe not. Making all the magnetic domains in the crystals of a metal turn the same direction takes TIME. Just turning off the electric current does not make the domains return to their original position. Meaning the magnetism will remain for some period of time.
Trial and error are necessary to find the correct pulse frequency for your project and you may find it will be necessary to REVERSE the current to the electromagnet to get the desired function.

Ferro-magnetism itself is a very fast quantum process (basically spin-flipping). Iron dust cored transformers work happily in 100's of MHz range for instance.

With a solid block of iron though you have eddy-currents to overcome, and this completely dominates the rate of magnetization. Once you break the metal up into laminates or particles eddy currents no longer can flow and things can work at full speed - for instance spinning disk drive platters use a coating of cobalt nano-particles to record magnetic information at GHz rates - no problem flipping the domain of those particles in sub-nanosecond timescales.

If you want a fast responding electromagnet it needs a laminated core, not a solid iron one.

Also a solid core will lead to much higher losses as you really have a transformer with the coil as primary and eddy-currents in the core as secondary - this can lead to much higher currents flowing. You'll notice that mains transformers and electric motors use laminated cores throughout to reduce these losses.

See project schematics in original post. My breadboard connection schematics are in post #10. Same hardware as the posted project Magnet Levitation with Arduino - Arduino Project Hub

This is the project in action...same hardware and code.