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Magnetic Reed Switches
Posted: Mon Oct 25, 2004 1:46 pm
by dhmai
Hello, My name is David Mai and i have a problem. I have some magnetic reed switches and i need to find a way how to stretch a signal reading. I put a part of a the switch on a part of a bicycle and the magnet on the wheel. I need to find a way when I keep pedaling on the bicycle that it would would always sense that the wheel is constantly moving instead of it sensing everytime the magnet passes by the sensor.
Posted: Wed Oct 27, 2004 5:25 pm
by shijun
Hi Dhmai,
This is an interesting experiment. Are you doing this project for a science fair? My question is: why do you need to know that the wheel is constantly moving? Your sensor only detects the signal when the magnet passes by, which is actually adequate for measuring the speed (if that's what you are after). Have you learned about angular velocity and angular acceleration? You can then convert it into linear speed if you choose.
But first tell me what you are trying to do.
Shijun
Science Buddies Staff
Posted: Thu Oct 28, 2004 1:30 am
by dhmai
The thing is that the wheel is always moving, but not at the same speed. For an example, a person on a bike would pedal at rate about 20 mph. After a while, the person would slow down less than 20 mph.
What i am trying to do is similar to making the speed rate of the wheel like an acceleration button trigger on a controller. When the bicycle is pedaled backwards, it would trigger a deceleration button.
Sorry if i sound confusing and vague.
Posted: Thu Oct 28, 2004 4:44 pm
by shijun
Well, it depends on how fine a "resolution" you want. In other words, how fast would you like the apparatus to detect change in angular velocity (or acceleration in other words)? Do you think having multiple triggers along the wheel would help? Why or why not?
Shijun