Self accelerating reed switch magnet spinner.

[TinselKoala]

Synchro is right, because the LED flashes with each magnet passage, with a single dot on the rotor, you will see four blurry images with the dot in each of the four positions, and arcs will be even worse. The flash has to happen once per rotation of the rotor, and there's another complication: the pulse is too broad to freeze motion. The rotor moves many degrees during a single flash of the LED! The pulse width required to properly freeze the motion of the rotor is surprisingly narrow. This narrowness makes the light from a standard LED pretty dim. Usable, but dim.

The 4017 solution to divide by 4 (or whatever other number from 0 to 9) is very easy to implement. Shortening the output pulse to the LED is harder... it has to be really short.

Please watch my next videos. I'm processing and they should be ready in a half hour or so.

[synchro1]

@TK,


       You could cut a narrow slit through a piece of paper and tape it to the LED.

[MileHigh]

I guess it depends what you want the strobe to do.  I wanted the "strobe" to be ON when the drive coil is being energized.  So it's not a "flashing strobe" it's a constant illumination for a short period time during the conduction angle.  I will call it a "pulse of light" to avoid confusion.

If you have only one dot on the top of the rotor then and there are four pulses of light per rotation, then what do you get?   Supposing that you are illuminating the area near the drive coil, and you are _looking_ at the area near the drive coil.   The first pulse of light illuminates the dot and you see a streak of white corresponding to the full conduction angle showing when the coil is energized.  The other three flashes just illuminate the red surface of the rotor.  So for every four pulses of light you get, "white-streak, red, red, red" and then it repeats.  This should still be easily visible to your eyes.  The white streak might look "translucent" but it will still be there.

There is no intention to freeze motion with the light pulse - you want to observe the changing conduction angle as you tweak the setup.

[TinselKoala]

http://youtu.be/iAke4OxujiE

[TinselKoala]

I guess it depends what you want the strobe to do.  I wanted the "strobe" to be ON when the drive coil is being energized.  So it's not a "flashing strobe" it's a constant illumination for a short period time during the conduction angle.  I will call it a "pulse of light" to avoid confusion.

If you have only one dot on the top of the rotor then and there are four pulses of light per rotation, then what do you get?   Supposing that you are illuminating the area near the drive coil, and you are _looking_ at the are near the drive coil.   The first pulse of light illuminates the dot and you see a streak of white corresponding to the full conduction angle showing when the coil is energized.  The other three flashes just illuminate the red surface of the rotor.  So for every four pulses of light you get, "white-streak, red, red, red" and then it repeats.  This should still be easily visible to your eyes.  The white streak might look "translucent" but it will still be there.

There is no intention to freeze motion with the light pulse - you want to observe the changing conduction angle as you tweak the setup.

Just please watch the video. All you see under your conditions is a blur. Don't forget that I have the hardware set up, this is NOT a thought experiment for me! You will never be able to see the angular display you are looking for under ordinary illumination. The way to get what you want is to have a double flash strobe hitting the beginning and trailing edges of the longish dwell.
I also have a bit of experience with strobes, flash photography, engine and motor timing issues, digital and analog electronics. As well as operating test equipment in order to make it do what I need to do. Just watch the video, it will be ready soon.