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Unread 07-02-2006, 17:25
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Joe Johnson Joe Johnson is offline
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AKA: Dr. Joe
FRC #0088 (TJ2)
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Re: Small motor used as sensor

Let's not get too worked up about this "Motors can't be Tachs" rule. I am not ready to go storm the gates and get these people to see reason.

In actual fact, motors make a pretty lousy tachometers compared to how easy an alternative is on a FIRST robot. Basically all you need to do is get a Banner Sensor or an encoder or maybe even a reed switch mounted to the thing that was going to drive the motor/tachometer and then use the RC calculate speed by either counting pulses per given time or by timing each pulse (which is a piece of cake, given Kevin Watson's many fine examples).

I would argue that there is almost always a better solution to the tachometer problem than using a motor as a generator.

It is an unexpected rule interpretation, but it is one I think reasonable people can live with.

Joe J.
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