Eureka!

Last time we were left wondering why the first motor I had built was not working. The instructions were reviewed twice before going to bed. The next day after school I was back at it again and started to troubleshoot or figure out why the motor wasn’t running. First, I checked the power source, we called them dry cells in the day, today we call them batteries. At that time we didn’t have a sophisticated battery checker from Radio Shack like we have today. In order to check the dry cells, I made a simple electromagnet and wired it to the posts on the dry cell. We wanted to be sure the cell was not worn out. Sure enough after wiring the electromagnet, it worked and it picked up a nail and held it tightly to the end of the electromagnet. The dry cell was working.

Next, I had to check the armature to be sure it was working. The armature is a lot like an electromagnet but it uses what is called a commutator to help switch the circuit. It is a little hard to figure out if it works or not. The best idea I came up with was to get two other wires and wire each to a different post on the dry cell. Then I would take the opposite ends of the wires and touch the two tin plates on the commutator. These two tin plates had the wires from the armature coils held in place underneath each plate. The thought was that when I touched the wires from the dry cell to the tin plates on the commutator, the armature would become like an electromagnet and nails or paper clips would be attracted to either coil. So, after making two wires about a foot long each and gently removing the plastic insulation, I attached them to the dry cell posts. Then, I pressed them on each of the tin plates. Sadly nothing happened – no reaction from a loose nail or paper clips. The good news is that I knew I was getting close to figuring out the problem.

Since this was my first motor I didn’t understand about “tight” connections to create a circuit. Also, I had not learned to solder, however, I knew that this was my problem. The excitement of figuring out the problem was energizing. After looking at the diagram of the tin strips, I thought it might be good if I would take the wires from the armature and bend them such that I would have a larger surface for the brushes to touch and not use the tin plates at all. I replaced the two tin plates by taking off the adhesive tape and then bent the two wires from the armature windings and left a little space between both wires. Next, it was time to put adhesive tape back on the commutator wires.

Once again, I tested the “new” commutator to see if it would pick up a nail or paper clips. If my suspicions were correct, this new method would make a circuit and the armature would act as an electromagnet. The moment of truth had arrived – will this work or not? I took the two wires attached to the dry cell posts and touched the two wires on the commutator. Yes, the circuit worked and the nail moved toward the armature and the paper clip moved toward the coil on the other side of the armature. The troubleshooting had worked!

All that remained was to assemble “The Tin-Can Wonder.” I was moving faster now because I could see the motor turning in my mind’s eye. Once again, the crucial moment arrived. When I wired the last wire to the dry cell post I saw the armature begin to move and then it stopped. Faster than swatting a fly, I gave that armature a spin and the motor took off humming! What a beautiful sight, what a relief – my first motor actually worked. Since that first motor I’ve never lost that same feeling of “eureka” when the motor turns for the very first time.

What did I learn through this? It is important to check your batteries with a battery tester or a multimeter (a device that can measure direct current and help you to decide if you have a created a circuit). The multimeter can help ensure you have at least 1.2 volts DC available. Secondly, be sure you follow directions and wind your wire correctly. In a few of my motors you have to remember to wrap the wire the same way when you move from one armature coil to the next. Third, it is important to have tight connections to complete the circuit. Fourth, the brushes should gently touch the commutator plates. Granted, the solution I came up with would not last very long in a production environment because the wires would get worn down and break off. But for this first motor build, it worked to great satisfaction for the builder and for my brothers, sisters and parents.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s