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.
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.
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.
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.
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.
This story is an EXCELLENT example of a real life engineering problem which should be mandatory in EVERY science, physics, chemistry, engineering curriculum, whether at the high school OR college level. Too many students learm the popular linear equations of phenomena (F=ma, e=ir, etc.), but fail to grasp that life is NOT solvable in linear terms. That's why mathematicians like TAYLOR, LAURENT, La Place, Newton, Leibniz, etal. spent countless hours developing higher order mathematical processes to explain and quantize these phenomena.
Altair has released an update of its HyperWorks computer-aided engineering simulation suite that includes new features focusing on four key areas of product design: performance optimization, lightweight design, lead-time reduction, and new technologies.
At IMTS last week, Stratasys introduced two new multi-materials PolyJet 3D printers, plus a new UV-resistant material for its FDM production 3D printers. They can be used in making jigs and fixtures, as well as prototypes and small runs of production parts.
In a line of ultra-futuristic projects, DARPA is developing a brain microchip that will help heal the bodies and minds of soldiers. A final product is far off, but preliminary chips are already being tested.
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