Hi am Sundar Murugan, an Electronics hobbyists and Photographer and this is my first attempt on writing an instructable. Today am going to demonstrate making of a simple Electromagnetic Glove which I have made during the last weekend. This glove basically uses the principle of Electromagnetic induction which everyone would have read in our 7th grade science.
SKILL LEVEL : Beginner (Electronics)
WHAT IT WILL DO: More for fun purposes, this glove is fixed with a DIY Electromagnet which is capable of attracting things when battery is connected to it. A small button was attached to bottom side of the index finger in order to make it easy for user to press with his thumb. When this button is pressed Electromagnet placed in the glove will get magnetized and demagnetized when it is released.
Let's take a look at the series of steps involved in making this Glove.
Step 1: Materials and Tools Required
In this project we are going to build the Electromagnet Separately and fix it on the glove. You will need the following materials for this project.
- Metal Bolt - 1 ( Magnetic core )
- Magnetic wire - 5 meters
- Biking glove
- Push button
- Connecting wires
- 9V battery - 2 pcs
- Battery Caps
- Utility knife
- Wire stripper & cutter
- Glue gun
- Soldering gun
- Magnetic core ( the iron bolt) can be substituted with other materials of you choice and it's preferable to choose a ferromagnetic material as you core. And the shape of core will have an impact on the magnetic field created by it. Here is an Interesting answer discussing the "Importance of magnetic core" to increase the strength of a magnetic field.
- I have used a small Iron bolt which I had ready, so you might choose any material that suits you.
Step 2: A Bit of Theory
"Current flowing through a conductor induces magnetic field around it"
This glove project works on the above principle and we all would have come across this in our grade 7. As shown in the above magnetic wire is wounded over the magnetic core. When voltage is applied across the ends of the coil. Magnetic field equivalent to the current flow will be generated and lines of force will start to flow from north to south pole.
Do remember we should use a magnetic wire ( a specially insulated thin wire widely used in transformers) for better magnetic field strength.
There are three important factor which decides the strength of magnetic field.
- Length of coil
- Number of turns
- Current flow in the coil
This is determined by the formula
H = I x N / L
where I - Current flow in the coil
N - Number of turns
L - Length of the coil in metres
These formula will help you to determine field strength. Note that these are not mandatory to know but helps to make calculations for battery selection and so.
There are also factors such as permeability of iron core that affects the strength of magnetic field. But that is beyond the scope of this article. You can refer to this article on "Electromagnets" for further explanation.
Step 3: Making an Electromagnet
Start by measuring the length of wire you are going to use and cut it out (for calculation purposes). I have cut out 6 meters of wire. Then wind the magnet wire over the steel bolt as shown in the above (image 2). Make sure the winding's are tight and close to each other as possible. Keep a count of the number of turns you are making over the steel bolt (for calculation purposes).
Once you are done with one layer of winding you need to start with another layer as shown in the fourth image. Adding layers of winding will increase the strength of magnetic field. Once you are done with the winding keep the ends of the wire protrude outside from the bolt so that it can be connected with the battery. Use the utility knife to remove the insulation from the both ends of the wire.
Step 4: Choosing the Battery
I have written choosing appropriate battery as a separate step since most of the tutorials and demo videos on making electromagnet failed to explain this. And this step is pretty much crucial than any other step for this project.
Never ever use rechargeable batteries for this project
In this project we are trying to connect the + and - terminals of a battery directly using a wire which in turn can be termed as short circuiting the battery since current flow will be high without any resistance present in the circuit. This is likely to destroy battery and in cases with rechargeable batteries it is likely to explode or catch fire or heat up dangerously.
Characteristics of a battery differs with the type of chemistry used in it. Batteries will have internal resistance in them so upon short circuiting the current flow will be limited by it's internal resistance. Rechargeable batteries (Lead acid, Lithium ion, NiMH) have very low internal resistance which in turn will allow large current to flow through ultimately end up catching fire. So a big no for these batteries.
It's safe to use small Alkaline or Carbon-zinc battery since these type of batteries have considerably high resistance and can withstand short circuit current for a period of time. It will heat up quickly while using though so continuous usage is not recommended.
Step 5: Testing the Electromagnet
Now the battery selection is done now we must choose the voltage rating of our battery. I need relatively a strong electromagnet. So I have started testing out the magnet bolt with 1.5, 9v battery. As you can see in the above images the field produced by 1.5v battery is relatively very small and I can only attract a simple coin out of that. On the other hand when i tried with 9v battery the strength increased and i can lift a 50ml tin can using the magnet.
I intend to increase the strength of field further, so I had connected two 9v battery in series which results in about 18v as you see in the third image. And the strength of the field increased further and this suffice my need for Electromagnetic glove. So my coil is going to be powered by 18v battery source.
I have used my multimeter to test the current flow through the coil when voltage is applied. And as you see in the final image I observed a reading of 1A current flowing through the coil. A typical 9v battery has a current capacity of about 150 to 200mah (current capacity will remain same since 9v batteries are connected in series). Considering the 1A consumption it's fair to say that your battery will lasts for about 10 to 12 mins of usage time with your glove. Although brief usage can extend this duration.
Step 6: Setting Up the Glove & Adding a Button
Now the electromagnet is all set to be placed in the glove. For this purpose I have used Velcro to affix the battery and magnet to the glove. Attach three velcro patch on the glove at the bottom and one at the wrist area where these three patches will get stick and support the batteries.
Another patch was used to attach the electromagnet to the center of glove. I have used hot glue for sticking these patches to the glove. You can use hot glue or similar strong adhesive to attach the velcro to your glove. Solder the battery caps with connecting wires to the push button as illustrated in the image 5. Place the button in at the side bottom of the index finger, this way it will easily accessible for the thumb to press the button(Image 6). Apply hot glue and fix the button in place.
Now place the battery to the caps and wrap it up. Your Electromagnetic glove will be ready.
Step 7: Put It on and Have Fun
So that's it your Electromagnetic glove is now ready. Take a look at some of the final images of this glove. Put it on and have fun with it. Now the glove is ready let's take a look at some of the drawbacks and improvements that can be done.
- The battery life will be very short ( depends upon the current your in the electromagnet coil) considering my glove as example you will get only around 10 to 12 mins.
- The magnetic core (Iron bolt) doesn't have wide contact area so the possibilities of attraction is greatly reduced
- Selection of magnetic core with better contact area can improve the glove functionality significantly.
- If one is familiar with sewing and stitching they can probably make some durable battery and magnet holder in the glove.
- Can add an extra switch to reverse the flow of current in the coil thus in turn switch magnetic poles. This will be useful when playing around magnets can choose to repel or attract a particular magnetic pole.
Do try this and comment how it turned out. And kindly vote for me in the "First time Author" and "GIFs challenge" contest.