On Thu, 4 Mar 2010, Karl Hammar wrote: > Why don't you put an inductive sensor [1] at the pedal gear teeth? > You could probably mount it at the chain protective cover if the > tolerances are the right. Have a look at Omron "E2E-X5MF1 2M" [2,3] > (you might have to paint it to protect it from water). For that one > you need 12-24V DC. This is a good idea... as long as your sensor and your uC can keep up with the pulses. I didn't look into the sensors that you picked, but they usually publish their response times... so you need to check that out. How many teeth does a typ. sprocket have? Say about 40T. Lance Armstrong spins his cranks at 80RPM. That would be 53.3 pulses/sec (or 1 pulse every 18.75 ms). Sometimes the sprockets have spokes or holes in them to make them lighter. Like 6 or 8. Perhaps sensing those would provide a more sensible signal if 18ms is too fast for your sensor/uC. -gabriel _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
