4 December 1998
Comments/Questions on Project 3 -- Beakman's Motor
While reading over the reports on this project, the following comments and questions came up quite often.
- Several people suggested using a lubricant, but only two groups noted that it was important to know the electrical properties of the lubricant. Only one group provided such properties.
- Can a PSpice simulation be done that looks like the voltage signal measured by the scope? How would such a simulation help with the design?
- What are the accuracy issues associated with the speed measurement? What should we do to obtain the most accurate measurement?
- No one used the details of the voltage data obtained in the speed measurement to motivate their design changes.
- Most of the explanations of improvements in the basic design were presented in a sort of stream-of-consciousness mode rather than in an organized, clear manner.
- A couple groups provided some information on motors in general. No one used this information well to generate ideas for improvements in the design. One group made a start on this, but did not go very far with it.
- In the presentation of the final design, almost no one provided enough information for someone to duplicate what they had done. Many details were left out or only discussed in a very qualitative manner.
- While it is not part of the suggested work for this project, it would be interesting to hear ideas on more elaborate measurements of the motor performance. For example, would it be useful to use a video camera to record the motions of the coil?
- Finally, no one approached this project in a systematic manner. At least no one presented their results in such a manner. By systematic, I mean that a series of design parameters are presented and then analyzed to determine which are the most sensitive. For example, there are quite a few resistances in the circuit. The resistance of the paperclip turns out to be one of the least important. The resistance of the battery is larger, but no one tried a battery with a smaller resistance. This was an option that may not have been really available, since NiCads are much more expensive. The resistance of the contact between the paperclip and the battery is very significant and can be easily changed. Many people noted that the motor worked better if they held the paperclips tightly to the battery, but no one got specific about the resistance.