The simple fix would have been to change the material and use a plastic that was a bit conductive. ESD-dissipative plastics Are a good fix for the static build up problem. Even though they are not good enough for shielding against interference or EMI radiation, they can reduce the static buildup. Of course not all molders are able to provide this material.
Notarboca, you are right. I think if we are listening to the comments and blogs, we can avoid most of design flaws and debugging issues up to an extent. Most of the designs may be theoretically correct, but may not work in practical. This may be due to some ignorance, unseen mistakes or sometimes by complication from components.
I would liked to have seen the expressions on the faces of his colleagues when the author brought it back to life by breathing on it. If ever there was a story that deserved the "Sherlock Ohms" designation, this one is it.
Great fix! Always love it when we 'more experienced folk' use our oft wide ranging experience to come up with a somewhat out of the box fix for a problem.
The Van de Graaff generator phenomenon is a well-known problem in belt-driven apparatus with no ground connections to the pulleys or to some object near the belt, and in paper-feed or similar mechanisms. These motors, however, didn't accumulate charge while running. Once discharged, they showed no further symptoms. It was during assembly that the charge was introduced. It might have happened as parts were removed from their stockroom packaging (the shutter wheel in particular), or handed by someone in Assembly with static-prone clothing.
Sounds interesting, Mydesign. Just so you know, we're always looking for fresh Sherlock Ohms stories. We're also eager to see any Made by Monkey stories of designs gone haywire.
Sounds as though the motor designers inadvertently created static-electricity generator similar to a Van de Graaff generator often seen in high-school science fairs. Nice solution to the problem.
Sherlock, quiet sometimes back (1998) I had designed similar BLDC motor using hall-effect sensors. There also we had used a photo voltaic transistor for smooth rotating of the motor, but initially it seems that the motor is rotating for a moment then slow down and then rotates. I mean a regular slowdown in between the rotation. Later we identified that at certain instances, the amplitude of the sensor output is not enough for driving the motor. So what we had done is, just injected an external pulse at regular intervals using a timer chip for making the signal strength constant and hence a continuous rotation.
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