Pulse Motors: MHOP #4 Development: LED Autostrobe Requirements

WARNING: Strobe and FLICKER! If you are sensitive to flicker or have a seizure disorder DON’T WATCH THIS VIDEO.
Contains flashing and flickering strobe LEDs.

Please watch the other videos in this series first.

The strobe needs 2 things: to flash once per revolution instead of at each magnet passage, and the flash needs to be short enough to freeze the motion. This means it needs to be about 100 microseconds or less. The 4017 decade counter’s output pulse width matches the period of the input pulse to the “clock” pin, so needs to be narrowed quite a bit. I use the DP101 pulse generator to determine how narrow that pulse needs to be to freeze the motion.

In the next video I show the use of a monostable 555 timer circuit to take an input pulse as trigger, and produce a single narrow output pulse. Since I’m operating at under 200 Hz, there is plenty of time for the one-shot circuit to reset and wait for another incoming pulse. The 555 should be able to do this at 500 kHz or more so there is plenty of “cushion” for higher speed operation of the strobe.

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