I want to make a digital speedometer. Concept is to measure the rpm of the wheel for say 5 sec. the revolutions will be counted by a counter. After every 5 sec the count is latched and the counter is reset. the latched count is fed to an EPROM which has the speed data fed in depending upon the wheel diameter. the output is the corresponding speed which is diplayed on 7 segment LED. Now my problem is HOW TO GENERATE THE PULSES FOR RUNNING THE COUNTER? need help on this please
DIGITAL SPEEDOMETER
Jun 19, 2006
4 Replies
==================================== There is a vehicle speed sensor on the transmission. Splice into this wire?
what is it for? A bike, car, machine?
Can you mount some magnets on the wheel and a sensor for them going past?
maybe some pieces of aluminum foil, and pick them up with an opto transmitter/receiver.
Shine a light rhtough the spokes (IR?) and detect the spokes going past with an ldr
Go buy one of those boxes of cereal that include a bike speedometer.
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BTW, your project is begging for a microcontroller.
If your pulse rate is low (like for the bike), magnets and reed switches are good. Magnets and coils or Hall sensors are better for faster rates. Opto (reflection or transmission) has issues with dirt.
GG
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