An electric motor made from three wires that can be made in five to ten minutes.
This is a great school project or as a simple Sunday afternoon parent-child bonding project.
What is needed:
- 12 volt Power supply. Preferably one that can supply a high current. A car battery is ideal.
- #10 to #16 gauge enamel copper wire. About eight to ten metres will be needed. Enamel wire can be bought from most electronics hobby shops, or, as I have done, any old large transformer is ideal to reusing its wire.
- Needle nose pliers.
- A large 100mm diameter can to wrap wire around to make the main coil. I used a small paint tin.
- A smaller 50mm diameter can or tube to wrap wire around to form the moving coil. I used a silicon sealant tube.
- Ten minutes of your time. Longer if making this with your children.
Step 1: Making the Base Coil.
If you are using an old transformer, cut the sides to allow for easier removal of the enamel wire. This is considered a previous step and not within the bounds of this instructable. Unravel about five metres of enamel wire.
Wrap the enamel wire around your 100mm can to make the base of the motor, as well as it is the basis of the main electro magnet. I made a coil of about 30 wraps.
Take both of the ends of the wire coming out of this coil and scape away all of the enamel, making a nice clean fresh-looking copper connection point.
Take the shorter of the two ends and make a few wraps around the coil, then with the needle nose pliers make a small loop and point it up in the air. It only needs to be about 50 to 75mm in height - this is one end of the support for the armature (the moving middle smaller coil). The other end wire of the larger coil can be wrapped around the coil to give support and then goes to negative on the power supply (battery)
Step 2: Making the Small Moving Coil (armature)
With the smaller 50mm tube, make 20 to 25 wraps of the enamel wire, forming a suitable coil as the moving armature. The end wires can be wrapped around the entire coil to give some support, and then finally flatten both end wires so they stick straight out. They only need to be sticking out 50 to 100mm long.
With your knife scrape away the enamel on one of the wires. Holding the 50mm coil flat, scrape away the enamel that is showing on top. Flip the coil over and scrape away the enamel that is now also on the top. Leave the enamel insulation in place on the two sides. Now do this for the other end wire. This is our electric contact points and it is this that is going to create the "make/brake" pulse in our eletrical circuit. So, in summary, if you were looking down along the axis of one of the two wire ends, and thinking in terms of North, East, South, West directions, you will have scraped away enamel on the North (facing up) and South (facing down). There will still be enamel insulation on the East (right hand side) and on the West (left hand side). When the smaller coil rotates, there will be an electrical connection in the support area for quarter of a turn, it will then be insulated for another quarter of a turn, another electrical connection for the next quarter of a turn, and the last quarter turn will also be insulated.
Step 3: The Second Armature Support
Take the final third length of wire (around 500mm in length) and scrape away all enamel on both ends. Wrap one end around the larger 100mm coil a few turns and then also make it stick up into the air for 50 to 75mm in length. Again with the needle nose pliers, make a small loop. This is the other supporting end for the moving armature. The other end of the wire will go to positive on your power supply or battery.
Insert the 50mm coil (armature) into the support wires that are on the main 100mm coil.
Step 4: Final Steps
Connect the power supply or battery, and if all connections are good, give the smaller coil a few pushes. It should start to move on its own, and continue to run.
However, this did take me a little while to get it working properly. I first tried one 12 volt 7ah sealed lead acid battery, and then added a second and finally a third battery in series to give a final 36 volts. My batteries ended up not being able to supply the required current, and is when I brought in a 50ah deep cycle 12 volt battery. The motor worked nearly straight away as you can see in first video up the top. A few helpful small turns of the motor, and away it went.
ADULT PRE-WARNING: The wires and coil can become too hot to touch after use. It is not immediate and does take some time for the heat to build up, however, this is a warning for those supervising young children handling the coils and wires after use. Please take care with your children. It is a great project for young kids to build, but does require suitable adult supervision. There is definitely enough time for the kids to play with it once in operation before it becomes too hot for them to handle the wiring with their bare hands. I could still easily touch the wires after three minutes of continual use, but at five minutes I could no longer touch either of the two coils and had to wait for them to cool down.