pserve
May 24, 2006, 01:46 PM
I'm making an on-board headspeed tach for an electric heli. I have a BASIC Stamp and hall-effect sensor that works nicely, but it's too big. I heard that I could use a cheap bicycle computer for the job, so I got one. It works too, except that it gets "lost" around 2300RPM. It uses some kind of mechanical magnetic pickup that just might not be sensitive enough for that speed, so I want to use the hall sensor with it instead. The stock pickup is normally-open, and closes momentarily when the magnet is nearby (I can hear it "click"). The hall sensor I have is a Melexis 90217 and has an open-collector output. For the Stamp, I just connect it to a pin with a pullup resistor and count the pulses. How can I connect it to the bike computer so that it will work like the stock pickup?