How to build a simple electric motor:
- An electric motor works by passing a current through a coil of wire. When the current passes through the coil it creates an electromagnetic dipole. A permanent magnet's magnetic field interacts with the dipole of the coil applying a torque to the coil. This torque is the force that makes the motor spin. In real electric motors there are complicated magnet and wire arrangements that enable the motor to be extremely efficient and powerful. The motor that you will be making is a simplified version of an electric motor and works on the same principles.
Estimated time: 45 min
Materials: - 1 meter of insulated magnet wire
- 2in bar magnet
- 1 two-way switch
- 2 large paper clips
- 1 1/4 in. foam board
- soldering iron
- 9 volt battery
- electrical tape
- thumb tacks
****** See embedded video for any clarifications
Step 1: Making the Box
1) Take the 1/4 in foam board and measure out 2 7in x 4in pieces, 2 1.75in x 6.75in, and 2 1.75in x 3.75in rectangles on the board.
2) Use an exacto-knife to cut out the pieces.
3) Once all the pieces are cut, glue the four smaller side pieces to one of the larger rectangles.
- The four pieces should overlap each in each of the four corners.
*Video reference time- 00:25
Step 2: Cutting the Top
The last piece of foam board will be your top.
1) The first thing you want to do is cut a hole in it for the switch. The hole should be large enough for the switch to slide in but not fall through the whole.
* You can put your switch anywhere on the top however I recommend putting it towards the edge.
2) At the center of the rectangle you will want to mark a square the thickness of your magnet. * Cut out the square from the side you will use as the inside; but DO NOT cut all the way through.
-You want to cut just one layer of the paper and scoop out the foam and leave just the top sheet of paper remaining.
3) Poke a small hole through the center of the carved out square.
* Video reference time- 02:57
Step 3: Making the Coil
1) Take about a meter of magnet wire and wrap it around a pill container.
*** Be sure to leave about 2 inches of wire on each end unwrapped.
2) Take each free end and wrap it through the center of the coil 3-4 times. Do this on both sides.
* Video reference time- 04:50
Step 4: Making the Terminal Supports
1) Take two large paperclips and straighten them.
2) Bend the paperclips into a y shape. These will be the terminals that will supply current through the coil.
3) Measure the radius or your coil. The length will be known as R.
4) Measure R from the bottom of the valley in the letter y down the shaft of the paperclip. Wrap electrical tape at this point and above.
5) Position the Coil over the small hole and mark about .25 in down each lead on the foam board.
6) Poke the paperclips through the foam board at these marks.
7) Wrap electrical tape around the paperclip on the bottom side of the foam to secure it in place.
8) Clip the ends of the paper clip so about a half inch is exposed underneath.
* Video reference time- 07:23
Step 5: Wiring Electrical Elements
*All the circuit elements will be connected in series.
**** Be sure to put the switch in the foam board before soldering.
1) Solder one lead from the switch to one terminal on the battery.
2) Solder the other lead of the switch to one of exposed ends of the paperclip.
3) Next solder a length of wire to the other paperclip and to the other open terminal on the battery.
4) Insert the end of the magnet into the cut slot. (I recommend taping it in position or gluing it)
5) Put the top on the box with all the circuit elements and magnet inside.
* Video reference time- 13:45
Step 6: Coating the Coil Leads
********THIS IS AN IMPORTANT STEP************
1) Strip the insulation of both ends of the coil. (Do this with either a knife or sand paper)
2) You are going to use a Sharpie marker to coat only half of one coil leads. Do this by placing the coil flat on the table and drawing on the half of the wire that is facing up.
*** You may need to re-coat a few times to get a good insulating barrier.
* Video reference time- 17:10
Step 7: Finalizing and Testing
1) Place coil on the terminal supports and turn switch to the on position.
2) Spin the coil to give it a start.
***** If the coil does not spin or twitches sporadically give the coated lead end a 1/8 turn to correct. Re-try the coil. Repeat correction if necessary. The key is the timing on when the current flows based on position of the coil in the rotation
* Video reference time- 19:05