## Introduction: Electromagnetic Fidget Spinner Accelerator

Fidget Spinners are little plastic toys with a bearing in the center. They are fun for a little bit, but get boring after a while due to their slow spinning speeds. There are ways to make them spin faster, but these methods involve using a bulky air compressor or an expensive can of compressed air. Luckily, I have found a cheap way to accelerate these fidget spinners to extremely high speeds with the power of electromagnetism. You can even hold the spinner in your hand while you accelerate it! I have clocked a spinner that is spinning with this accelerator at speeds up to 1440 RPM, that is fast. You can build this accelerator too, it is really cheap and really simple to build.

The video below compliments this instructable and shows this awesome Electromagnetic Fidget Spinner Accelerator (EFSA) in action!

Lets Get Started.

## Step 1: How It Works

This fidget spinner accelerator works by using an electromagnet with a reed switch and a fidget spinner with magnets mounted on the 3 sides. First of all, the magnets on the fidget spinner are mounted so that all the magnets have their north pole facing outwards. The electromagnet is wired so that the side that is closest to the spinner will have a north polarity when it is powered. When the spinner starts spinning (Refer to the above diagram) the electromagnet will be off. As the magnet on one side of the spinner passes the electromagnet, it will trigger the reed switch, activating the electromagnet. Because both magnet and electromagnet will now have the same poles, that arm of the spinner will be pushed away from the electromagnet. When it moves far enough away, the reed switch will disengage and shut off the electromagnet. Because the spinner will be spinning from this first cycle, it will have enough momentum for the next arm to move past the electromagnet and reed switch and repeat the cycle. As each arm moves by the electromagnet and get repulsed, the spinner will speed up and gain momentum. That is how this system of acceleration works!

Now, for how the circuit works. The reed switch alone cannot handle the high currents that the electromagnet draws, so it will need a buffer between it and the electromagnet. This buffer will be a MOSFET transistor. When the reed switch is triggered, it will let current flow from VCC to the gate of the MOSFET. This will allow current to flow form VCC, though the electromagnet, into the drain of the FET, and out of the source back to ground. The diode on the electromagnet is called a flyback diode, and its purpose is to absorb all the excess energy created by the collapsing magnetic field of the the electromagnet. Without it, the MOSFET would potentially be fried. The resistor from the gate of the MOSFET to ground serves to drain the excess charge from the gate after the reed switch turns off. Because the gate of the FET has capacitance to the source, this means that even after you remove power form the gate, the MOSFET will still be on, causing the circuit to constantly be on. The resistor prevents this.

## Step 2: Materials

For this project, you will not need very many materials. You will need:

• A 3 arm Fidget Spinner(Well Duh)
• Small Ceramic Magnets
• A piece of perf-board
• An N Channel MOSFET(Almost any one will work)
• A magnetic Reed Switch
• A 10k resistor
• A 1n4004 diode
• Wire
• Terminal connectors
• 12 Volt Power Source (Batter or bench power supply)

## Step 3: Tools

For this project, the tools you will need are:

• Hot Glue Gun
• Soldering Iron
• Wire strippers/cutters
• Hacksaw

Optional:

• Oscilloscope

## Step 4: Setting Up the Spinner

To set up the spinner, you will just need to take three magnets, and hot glue them to the three arms of the spinner. Now, when you attach the magnets, make sure that the same side, or pole, of each magnet is facing out. This means that after you are done gluing them in place, you should be able to take another magnet, and hold it to all the magnets with the same side, and get the same reaction. In my case, there was an indentation on the north pole of the magnet, so all the indentations faced outwards.

You will also need to make sure that you use the same amount of hot glue for each side. If you do not, then your spinner will be unbalanced. It is also important to use a lot of glue, if you don't, then a magnet might fly off due to centrifugal force, also known as tangential velocity. This might cause, I don't know, maybe a dent in the wall? (I know from experience. Haha). It will also cause your spinner to become unsafe. Now, it is time to start building your circuit!

## Step 5: Choosing an Inductor

The inductor is one of the most important parts of this project, it acts as the electromagnet that makes the spinner spin. This means that you will have to find the perfect inductor. You can start by digging through your parts drawers of inductors. You will first need to find an inductor that has the perfect resistance, and is not magnetized. Some inductors are magnetized, and these will not work, so before using one, hold it up to a piece of metal. If it sticks, don't use it. You also need to find an inductor with the right resistance. To high of a resistance, and the feild will not be as strong. To low of a resistance, and it will draw too much power. My inductor came out of an old TV board. It is 2.9 ohms and 5.82mH. Make sure that the inductor you choose is made of a ferrous material.

To test your inductor, set you fidget spinner down, and connect the inductor to a power supply. Then, tap the power supply leads on and off the inductor pins while moving it near the spinner. It should cause the spinner to spin! You may have to go though some experimenting to find the right inductor for your project.

## Step 6: Cutting the Perf-board

The perf-board is what holds all the components of the EFSA. You will need to cut it so it is large enough to hold all the components for your accelerator, but not too big. You will also need to cut a triangle off of one end to hold the inductor. I made all the cuts in my perf-board with a hacksaw.

## Step 7: Soldering the Circuit

This is one of the most difficult parts of this project. You will need to follow the circuit diagram to solder all the parts of the board in place. The positions of the reed switch and the inductor are very important. The reed switch needs to be far enough away from the inductor so that the magnetic field will not cause the circuit to self trigger, but close enough to make the circuit run as efficiently as possible. You will need to do a little experimentation to find this sweet spot. I used screw terminals to connect the inductor and the power wires to the board. You will need to make sure that all the connections shown on the circuit diagram are soldered on the perf-board in real life. Look at the pictures closely to find further know how to solder this board. When you are done soldering the accelerator board, then you should be ready to test it!!

## Step 8: Power Supply

This fidget spinner accelerator needs a power supply that can provide 12 volts at 1.5 amps. This power draw will change based on the specs of the inductor you use as an electromagnet. If you just want to use this accelerator at your desk, then you can just connect it to a good bench power supply or computer power supply. If you want to make it portable, then you can use a LiPo or LIon battery. To find out how to make your own 11.1 volt LIon battery, check out my instructable and YouTube video below.

https://www.instructables.com/id/LiPoLIon-Batterie...

## Step 9: Finding the RPM

To measure the RPM of this fidget spinner, all you need is the accelerator and an oscilloscope. First of all, you will need to connect the probe of the scope to the gate of the mosfet. This pin will be high 3 times per revolution because the magnets on each arm of the spinner will trigger reed switch each time they pass it. Then, ground the oscilloscope to the ground of the accelerator. Finally, get a friend to use the fidget spinner accelerator while you look at the oscilloscope. After the spinner was up to full speed, the scope registered a frequency of 72 Hz. This means that magnets were passing the reed switch 72 times per second! You can divide this number by three to find the rounds per second, which would be 24. You can then multiply the RPS by 60 to get the RPM: 1440. This fidget spinner accelerator really makes the spinner spin fast.

## Step 10: Have Fun!

To use your spinner with the accelerator, simply hold the spinner with one hand and the accelerator in the other, then give the spinner a little jump start. After that, hold the accelerator closer to the spinner without touching it, and you should see it start to accelerate! The closer you hold the accelerator, the faster it will go!

This device is really a lot of fun. It is especially cool to feel the gyroscopic effect of the spinner at these high speeds. You can also impress your friends by spinning your spinner faster than any of them can. The Electromagnetic Fidget Spinner Accelerator turns a regular old fidget spinner into a truly awesome toy.

Thanks for reading and good luck building! Also, remember to vote for me in the contests!

Third Prize in the
Power Supply Contest

Runner Up in the
Invention Challenge 2017

Runner Up in the
Explore Science Contest 2017