Hello. I've created a little program that I'll use to project a Persistance of Vision image on the area of a bike wheel. To have the image synchronized on the wheel, regardless of the speed you're travelling I have decided to make the program rely on digital input from a sensor that counts the number of bicycle wheel beams that pass per second. The problem is, and here is where I need some help, that I don't know what kind of sensor to use. I'm thinking of some kind of laser or photocell sensor that basically senses when the "beam" is broken, sending 0 when it's broken and sending 1 when it has contact. Any help and advice is highly appreciated.
Thanks in advance.
/Shan
A simpler method might be to mount a small magnet on the wheel and have a fixed hall-effect switch sense the magnetic field as it passes by.
Lefty
Hm, that sounds like a good alternative. Will it be able to sense the changes in the magnetic fields even when biking very fast? There might be up to like 80 beams per second that passes by.
Shan94:
Hm, that sounds like a good alternative. Will it be able to sense the changes in the magnetic fields even when biking very fast? There might be up to like 80 beams per second that passes by.
No problem at that speed.
Lefty
retrolefty:
A simpler method might be to mount a small magnet on the wheel and have a fixed hall-effect switch sense the magnetic field as it passes by.Lefty
Lefty,
I see more often the other way around 
The circuit will rotate with the hall effect sensor switch and a magnet (small and strong, what are they called?) is strapped on the fork facing towards the wheel.
Try this one:
I use it on my POV system. It's not a bike wheel though.
liudr:
retrolefty:
A simpler method might be to mount a small magnet on the wheel and have a fixed hall-effect switch sense the magnetic field as it passes by.Lefty
The circuit will rotate with the hall effect sensor switch and a magnet (small and strong, what are they called?)
the small magnects are called neodymiun, are very strong and with a hall effect sensor, its enough for your project
Thanks. The electron shell structure seems to produce some magnetism. I'll read up on neodymiun in the afternoon.