Introduction: Single Coil Induction Motor / Electric Motor
In this project we are going to make a Single coil induction motor
Comercial, and much more elaborated, versions of this electric motor are used in most alternate current appliances.
Our motor does not have high torque, it is more about the working and study of variables that influence its operation.
Be careful, we are about to handle with 110V AC electricity, which can be dengerous.
An interesting point of this motor is that there are no brushes. The coil or anything never touches the rotor. It seems like magic.
I kept the instructions as short as possible... if you have any doubt I would be glad to asnwer it!
Check the video to see it spinning. You tube video
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Materials Required
- - Coil core - made from a hexagonal head steel bolt - check dimensions on the picture
- - The coil has 600 turns of magnetic wire (diameter about 0.3 mm).
- - There is a small plastic ring I used to keep the wire in its place. It is not mandatory but it is good.
- - Steel can lid. Try to find a similar to the one in the picture. For sure you can try with smaller diameters.
- Transformer - This is important. I've got good results with a 110V to 12V transformer able to provide current of 3A.
- Copper ring - see dimensions on the picture
- Steel bracket -see dimensions on the picture
- Plastic conector - any small conector able to hold the wire will do.
Step 2: More Materials
9. Mdf base plate. Our base is made from a 6mm mdf wood plate, but any piece of wood similar to that will do.
10. Pivot made from a steel 3/16 flat head screw. See picture and drawing.
11. Central bearing. cut from a 1/4" steel screw. See picture and technical drawing.
12. Coil support - made from wood. Any kind of wood will do. check technical drawing.
13. 4 flat head, steel screws, 3/16" threaded 2" long.
14. 5 hexagonal steel nuts, 3/16" threaded
15. 5 3/16" washers
16. 2 hexagonal, steel nuts, 1/4" threaded
17. 2 1/4" washers
Step 3: Making the Parts
This project requires some power tools... be careful...
1. Start with the base. Cut outer shape of the base with a saw following the drawing. For the holes you will need a drill machine, a 5mm drill bit, and a 10 mm drill bit. Trace the hole centers and make the holes. The 10 mm drill bit is used ONLY to house the heads of 3/16" screws. Do not allow the 10 mm drill bit go through the plate!
2. Now, it is time to prepare the coil. Find a large screw as similar as possible to that one shown in the picture.Now wrap the 600 turns of magnetic wire near the hexagonal head. I kept the magnetic wire in its place with the help of a plastic ring. If you can find a plastic ring that fits on the 12 mm screw, it would be the best solution, but I know it is hard to find. Or, you can always use insulating tape to keep the coil in its place instead.
3. Now, some metal machining will be required. The central bearing is cut from a 1/4" steel screw which has at least 20 mm long thread. After having cut the screw comes the difficult part. You will have to set the screw with the help of the nuts on a vise and make a 3 mm hole right on the center of the screw. This can be a little bit easier if you punch a center marking first. Be patient... this is hte hardest part. (see the picture)
4. Maching the pivot. Set the 3/16 flat head screw into the mandrel of drill machine. You can use the 3/16 nuts for a centering help. Now, grab a file, turn on the machine and remove the material until you reach the specified diameter. (check the drawing). Yes, this is boring... be patient here.
5. Make a 6.5 mm hole right on the center of the steel lid. Some precision is required here because it will help in the performance of the motor.
Step 4: Mount Everything...
1- Mount the central bearing on the lid with the help of two 1/4" nuts and washers.
2- Fix the assembled coil on the wood block with the help of the bracket and only one 3/16" screw.
3- Fix the pivot and transformer on the base plate with the help of 3/16 nuts and washers.
4- Fix the coil sub-assembly on the plate using the other 3/16" screw. This will allow the coil assembly to incline towards the seel lid in order to calibrate the distance between coil and lid. (check the video).
Step 5: Wiring...
1- Connect the 12V side of the transformer to the coil.
2- Connect the 110V side to the connector. From the connector to the AC mains you will have to use a cord and a wall plug. Check the picture for a better understanding.
Step 6: Operation
1- Before connecting to the AC mains pick the copper ring and hang it on the coil screw until it touches
the end of the coil, or plastic ring.
2- Center, the best as you can, the central bearing on the lid.
3- Turn on the power and approximate the coil to the lid until it starts spinning.
You will realise that the Lorenz force that builds up on the copper ring drags it until the best position.
Approximate and move away the coil for you to see the effect on the speed of the disc.
Please check everything twice before connecting the motor!!! And have fun!!
There is heavy and wonderful theory behind the working of this motor. If you are interested in technology it is worth learning about it on the internet.