Introduction: Fidget Spinner to Brushless Motor

Picture of Fidget Spinner to Brushless Motor

Fidget Spinners have become the latest fad. I was curious about them so I ordered one from eBay and spun it a bit. While it was great fun for a short time it left me bored and wondering what else it could be used for.

Having once taught science to elementary school students I remembered trying to explain to them how an electric motor worked. The bearings in the spinner and the overall shape reminded me of the armature in a simple DC motor.

I set about building a few different motors, ranging from a very simple one to one that is way too complex. I found this part of the spinner experience was more fun that just spinning them.

This article presents what I have done in hopes that you might enjoy experimenting with them, too.

Step 1: A Sturdy Base for Experimentation

Picture of A Sturdy Base for Experimentation

The base for all of the following examples is the same. It is composed of a 4" or 5" square piece of pine or plywood about 3/4" thick. A 5/16" hole is drilled in the center to accommodate a 5/16" x 3" carriage bolt. The bottom of the hole is drilled out with a Forstner or spade bit to countersink the head of the bolt.

The 5/16" bolt fits nicely inside of the center bearing of the spinner. Additional nuts can be put onto the bolt to raise the spinner above the platform.

Step 2: Building the Electromagnet

Picture of Building the Electromagnet

While an electromagnet can be made in many ways and just about any one will work for these experiments I decided to wind mine onto an empty plastic spindle that would normally be used to hold thread for a sewing machine. The wire I used is called magnet wire and is copper wire coated with a colored enamel coating that must be removed from the ends to make connections to the other parts of the motor. For some coils I used 34 AWG magnet wire and for others I used 28 AWG wire. They different coils worked equally well.I put the empty spindle onto the shaft of a hobby motor that was placed into a vice. I applied a low voltage to the motor. Just enough to spin the shaft but not too much that I couldn't stop it spinning by pulling back on the wire. See the video for more information on how to wind the coil.

The coil was mounted to a piece of wood or acrylic so that it can be mounted to the same 5/16" bolt that holds the fidget spinner.

Step 3: A Simple "Spinner" Motor

Picture of A Simple "Spinner" Motor

The simplest motor I could come up with uses only a few parts:

  • A basic 3 lobe spinner - eBay (search for fidget spinner tri)
  • A wood base about 4" x 4"
  • A 5/16" x 3" carriage bolt + 5 nuts
  • A micro switch with lever - eBay (search for micro switch lever)
  • Three strong disk magnets about 1/2" in diameter - eBay (search for disk magnets) (see text)
  • An empty thread spool - eBay (search for Clear Bobbin Thread Plastic Empty Spool) (see text)
  • Enameled magnet wire - 28 to 34 AWG - eBay (search for magnet wire 36 AWG copper) (see text)
  • Connecting wire
  • Battery or power supply to provide 6 to 12 volts (see text)

The circuit is quite simple. A magnet is placed on each of the three outer arms. Make sure that the same pole faces up on each arm or the motor may not work. I used neodymium magnets, also called rare earth magnets. It is important that all three magnets are identical so that the spinner is balanced.

An electromagnet is placed over the arms so that they pass by it as the spinner rotates. A micro switch is hit by the arms as they pass by. This turns on the electromagnet pulling the nearest magnet towards the electromagnet. As the arm & magnet approach the electromagnet the switch turns off allowing the magnet to coast by.

Spacers can be added between the nuts and the coil mount to position the electromagnet just above the magnets - close but not touching!

I found that the switch and electromagnet needed to be about 90 degrees apart for the motor to work well. See the video for more details about placing the switch and coil.

The schematic is very simple, just the switch, coil and power supply or battery. I found that the spinner would work with as little as 4 volts and really got moving when I applied as much as 12 volts. Note that higher voltages may lead to the magnets being flung from the spinner and can get the coil heated up quite a bit.

Step 4: A Simple "Spinner" Motor With a Reed Switch

Picture of A Simple "Spinner" Motor With a Reed Switch

The spinner that uses the micro-switch works well but could be better. The impact between the spinning rotor and the paddle on the switch surely slows things down. What is needed is a non-contact device that will turn the electromagnet on and off as the micro-switch did.A reed switch fits that description as it is a small switch that is turned on when it comes near a magnetic field.

The switch is made up of two small metal plates (reeds) that are magnetized so that they normally oppose one-another keeping the switch off. When the glass vial that holds the reeds comes close to a magnetic field the reeds touch turning the switch on.

One word of caution when working with reed switches. Never try to bend the wires that extend from the glass vial by holding the glass and bending them - the glass will break ruining the switch. Hold the wire close to the glass with a pair of needle nose pliers and bend from that point.

Here we can see the rotor with magnets on the ends of its arms. The electromagnet is circled in red and the reed switch is circled in yellow. Two plastic washers (spacers) were used to adjust the space between the reed switch and the magnets on the fidget spinner.

The reed switch schematic is almost identical to the one that uses the micro-switch. The diode (D1) is optional but is likely to extend the life of the reed switch. This is due to a back pulse (back EMF) being generated when the coil is turned off. This pulse of energy can weld the reed switch's magnetic plates together so that it is always on.

Step 5: A Solid State Magnetic Sensor, the Hall Effect Sensor

Picture of A Solid State Magnetic Sensor, the Hall Effect Sensor

Many brushless motors use Hall sensors, a 3 pin solid state device that senses a magnetic field.

This device cannot control a high current device like the electromagnet so it must connect to the coil through an interface that triggers a power transistor whenever the magnet goes past it.

The additional parts are a common NPN transistor (2n2222 or equivalent) and a Mosfet power transistor (IRL520 or similar). Here the diode that goes across the coil's terminals is not optional as it was with the reed switch. If the diode is not in the circuit the Mosfet will fail after some amount of use due to the back EMF pulses damaging it.

  • NPN transistor (2N2222) - eBay or Amazon
  • IRL520 Mosfet - TO220 case - eBay or Mouser
  • Diode (1N4001) - eBay or Amazon
  • Hall Sensor - eBay or Amazon
  • 100K resistor, 3 @ 1K resistor

Step 6: An Optical Switch

Picture of An Optical Switch

While the reed switch works very well and doesn't directly touch the rotor it still can slow down the rotation a bit as each time the magnet passes it they are attracted magnetically. An optical switch, on the other hand, has no physical or magnetic connection to the rotor. It can be made from a few additional parts. We use the same electromagnet and the same magnets on the arms of the fidget spinner. We then add an LED that is aimed at a phototransistor that will be in shadow when the rotor passes by.

In addition we need a transistor that acts as an on/off switch to activate the electromagnet. A standard NPN transistor will probably work but the most efficient device that I had on hand was an IRL520 Power Mosfet. This device has a very low resistance when turned on and will easily handle the power drawn by the circuit.

The phototransistors that I used are in a metal can and have three leads. The center lead (the base) is not used and can be snipped off. The tab is next to the emitter.

Phototransistors like the ones I used are available from eBay and Amazon.

The schematic is very similar to the one used with the Hall sensor.

Step 7: How Fast Does It Spin?

Picture of How Fast Does It Spin?

You can measure the speed of the Fidget Spinner by hooking up the circuit with the phototransistor to either a multi-meter that can measure frequency or to an oscilloscope.
Connect the negative probe from the meter or scope to ground and connect the other probe to the output of the phototransistor (Q1) just below resistor R1.

This photo shows my meter set to Hz Duty. The measured frequency is 71.54. That is the number of times that the light sensor was put into shadow by the spinner arms. Since there are three arms we need to divide by 3. That gives the speed in revolutions per second.

To get revolutions per minute multiply by 60. Or you can just multiply the displayed reading by 20 since that is the same as dividing by 3 and multiplying by 60. In this case the spinner is rotating at over 1400 RPM. Not bad for a simple toy!

This screen is from my oscilloscope and shows a speed of a bit over 44 Hz, giving a speed in revolutions per minute of almost 900.

Step 8: Going Further

I hope you have a chance to give some of these experiments a try.

If you want to see what can be done by hooking up the coil and a sensor to an Arduino for even more experiments please drop me an email and let me know. dave@davebodnar.com or leave a comment here.

Comments

RobertHunX1 (author)2017-10-26

Hi Dave,

I have made a working version of this project and it works great. My only problem is that I can't seem to get my RPM's pass 830 RPM. I have tried changing out the mechanical aspects of my project but with no improvement. What can I do to increase the RPM's by changing the circuit? I would also like to know if it were possible to achieve 1000RPM's with say only 5-6VDC?

davebodnar (author)RobertHunX12017-10-26

I responded to this earlier but it must have gotten lost in the Ether!

First of all, good deal on making the motor!

Things that you can try to change the speed:

1. Use a higher voltage - take care not to get the coil too hot

2. Use stronger magnets

3. Use more wire in the coil

4. Move the coil closer to the magnets

5. make sure there is no binding or wobbling in the spinner

6. Get a spinner with better bearings.

Let us know how it goes!

dave

mmb3 (author)2017-10-05

Hi Dave I made a version with freq measurment and servo adjustment using an arduino and rotary encoder to adjust the hallsensor by driving a servo
https://youtu.be/oQ9W5kB-Pjw

davebodnar (author)mmb32017-10-05

Your project and video are SUPER! Thanks for letting us know of your adaptation.

Keep up the good work!

thanks

dave

mmb3 (author)davebodnar2017-10-05

I have to thank you for the very good idea

davebodnar (author)mmb32017-10-05

I just checked out your web page, too.

http://wvs-k.weebly.com/fidget-spinner.html

Also very well done.... Thanks!

dave

jmogyoro made it! (author)2017-06-29

Hi Dave, Thank you for your instructable. I used it to teach my daughter, starting at "what is a magnet". Then we made an electromagnet with a nail and coiled wire, and worked our way up to the fidget motor with reed switch. I have access to a 3d printer so I designed some parts to hold the magnets and spool, so I could hold the whole thing in my hand. Since every kid has one of these useless toys in their pocket, why not trick them into learning something :)? To wrap the wire around the spool, I stuck a pencil into my hand drill, then put the spool onto the pointed end of the pencil. Thanks again. Here it is in action: https://youtu.be/X0RGxPEvAjo

mcalik77 (author)jmogyoro2017-09-21

hi JMogyoro ,

I am trying to make this one. I printed those part. How did you make the wire spool ? Did you use nail inside of coil wire or plastic ? What battery you used for wire ? Did you put magnet upside down ? Thanks.

jmogyoro (author)mcalik772017-09-21

The author of this instructable explained how to make the spool. Follow his instructions. There in nothing in the center of the spool. I used a variable power supply and varied the voltage as part of the experiment. Magnet upside down? I don't know what you mean. You can design it so that the magnets will repel the electromagnet or attract. You can experiment to see if one way works differently than the other which is part of the fun. Thanks.

dbmellen (author)jmogyoro2017-09-08

Would you provide a copy of the files to print the parts and a parts list? I teach a high school electronics course and have access to a 3d printer. This looks like something I can use.

jmogyoro (author)dbmellen2017-09-08

I sent the answer to your question in a private message to you since it was kinda long and this is not my instructable. thanks

davebodnar (author)dbmellen2017-09-08

Good day - I did not 3D print any of the parts - several of the supports were done with a laser cutter but could just as easily be cut from acrylic or wood with a hand saw and a drill.

The parts that I used are described in detail within the Instructable - you should be able to easily identify what you need.

Please let us know how your experiments go with the spinner!

thanks

dave

jmogyoro (author)davebodnar2017-09-08

Hi Dave, I think the user dbmellen was asking me about the 3D printed parts I made. This comments section is a bit confusing. There is just that little arrow pointing to me. Anyway I will answer dbmellen shortly and respond to him here.

davebodnar (author)jmogyoro2017-06-30

That is wonderful! I appreciate your taking the time to show us what you have done and how you used it with your daughter.

Keep up the good work!

thanks!

dave

rclacovara (author)2017-09-14

Very nifty. BTW, the diode across the reed switch is often called a "flywheel diode".

davebodnar (author)rclacovara2017-09-14

I have never heard that expression - thanks for the info

dave

jeanniel1 (author)2017-09-10

Wow, really great explanations. Appreciate it and for a simple project to start with - I can actually understand it all!

R A Shah (author)2017-09-08

That is really great... A very advance project even a child can build..

JamesE166 (author)2017-09-07

Just Wow man!
The nerd is strong with this one :)

davebodnar (author)JamesE1662017-09-08

Thanks, Yoda!

dave

RuiC35 (author)2017-09-07

Hold on a second. I don't understand anything about electricity but...an engine runs something right? What is this engine running? The spinner?

We're taking some small voltage and with the help of neodymium magnets we're just spinning a spinner. Is that it?

Thanks

davebodnar (author)RuiC352017-09-07

I suppose that doing useful work could be one definition of "motor" but this is what is generally referred to as a demonstration motor -

If you want it to do "work" you could add a turbine or vanes to the spinner and make it a fan!

Hope that makes sense

dave

RuiC35 (author)davebodnar2017-09-08

Fair. It's just that I am a big ignorant when it comes to electricity and I was afraid that maybe I didn't notice the actual work the motor was doing. Now I've got your confirmation that it is "only" a demonstration motor.

Thanks, Dave.

pgabriel3 (author)2017-09-07

How useful would this be as an electric generator?

What specific elements would need to be altered in executing the design to make this work AS such an electric generator?

avayan (author)pgabriel32017-09-08

Add some kind of wind resistive flaps to the fidget spinner, and connect your load to the coil. As the wind moves the fidget spinner, you will get some energy out of the coil. Put more coils and you will get more energy out. Be aware, there is a gazillion ways to do this better than with a fidget spinner. Not to mention there has to be a fair number of instructables on how to construct your generator, so rest assured the information is out there. Good luck!

JimTheSoundman (author)pgabriel32017-09-07

@pgabriel3 - Why would you want to use an electric motor to generate electricity? Doesn't make any sense. Electric generators are usually powered by something other than electricity, such as steam or water or gasoline or diesel fuel.
But yes, a electrical generator works on basically these same principles. Instead of using an electromagnet to spin a wheel, you are doing the opposite, spinning the wheel first with a turbine or a pulley or belt, and the interaction between magnetic forces will then generate electricity.

Nirgal38 (author)JimTheSoundman2017-09-07

I think he means that you drive this with some external mechanism to have it generate electricity.

If you use a simple DC motor like the kind from a toy car, if you spin it with your fingers or attach some kind of fan blade to it, you can get it to act as a generator (although not much voltage or current). I've lit an LED this way just to demonstrate the principle.

I honestly don't know if a brushless motor would do the same thing if you were to spin it up by hand.

discostu956 (author)2017-09-07

This is great instructable!! Educational, and done in a way that makes it seem fairly easy for anyone to attempt. You've explained the why as well as the how

You've also managed to achieved something that I thought was impossible-make something relatively useful out of a fidget spinner!!

bmiller91 (author)2017-09-07

Is it ironic or poetic to turn a device which takes perfectly good industrial bearings and turns them in to junk back in to a functioning device? ;-)

mikroprofesszor (author)2017-09-07

Hallo Dave,

I've really enjoyed your instructables, nice work! Do you have any hungarian relation because your mind (and your name) is like a Hungarian

ThatMike1 (author)2017-09-07

Dave,

This has to be one of the most informative instructables I have seen. Your video is complete and understandable from start to finish. I made many motors as a kid and using a fidget spinner is absolutely ingenious. Wish I could have had you as a science teacher! Thanks!!

davebodnar (author)ThatMike12017-09-07

What a wonderful comment, ,Mike - you are quite welcome & I bet you would have had in my science classes, too!

enjoy

dave

ajayt7 (author)2017-09-07

Wonderful

Dragonavionics (author)2017-09-07

RUIC35

All motors are engines but not all engines are motors, The spinner is part of the motor.

Great instructable by the way!

veloci (author)2017-09-07

Brilliant, creative idea. Loved the detailed instructions

ShannonW49 (author)2017-09-07

Nicely done. I now understand how brushless motors work, the various ways it can be implemented, and some pros and cons for each method. Thanks for your work. I really enjoy well done "concept instructables" because I always like to know why things work, not just how to do it. Also, I didn't realize reed switches could switch on/off that quickly. (or that mechanical switch, for that matter)

tanner_tech (author)2017-06-07

That is a pretty cool project! It's funny, I just did almost the exact same project about a week ago! I am working on an instructable on it too. It is really cool that you measured your rpm on an oscilloscope, because that's exactly what I did. And I got 1400 RPM too! Nice project!
-Tanner_tech

davebodnar (author)tanner_tech2017-06-07

That is good to hear, Tanner - I look forward to seeing your project

dave

bluenote27 (author)davebodnar2017-09-07

thank you. terrific instructable!

ErikA45 (author)2017-06-15

Amazing what you do here: fantastic educational tool for tech high school kids; it shows some great principles of brushless motors in a very down-to-kids-world manner. I admire your work! Erik

davebodnar (author)2017-06-14

Jimmy - those two resistors pull the terminals they are connected to a high state (5-12 volts).

If they are omitted the terminals would stay low (pulled to ground) even when turned off.

dave

jimmyzmhuang (author)2017-06-14

Hi Dave Very nice. Several options. I have a simple question. In Step 5, why are R2 and R4 included? Thank you!

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