Subject:
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Using the Motor as a Tachometer
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 17 Feb 1999 01:35:02 GMT
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Reply-To:
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nospam-dcchen@pacbell.net!Spamless!-nospam
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Viewed:
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1108 times
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I don't know if someone else has already written about this, if so,
sorry about being repetetive.
I was reading about hooking up 2 motors A + B and arriving at a
dynometer arrangement. ie. Turning A causes B to rotate.
I tried this, but also hooked up both motors to an Input port that was
set up for RAW readings (don't ask me why, I was just messing
around...). Lo and behold, a RAW input reading was generated
proportional to the speed at which the motors were turning.
I re-configured for just 1 motor and I was able to replicate this, thus
with this curcuit:
+-----+
|Motor|----->Sensor Input = proportional to Motor RPM
| | Just measuring the voltage being
+-----+ generated by turning the motor. I think.
Three downsides.
1) You use up a perfectly good motor for a tach.
2) The Input reading maxes out at 1024 pretty fast so the motor has to
be geared down (ie. slow down RPM's at the Motor relative to the input).
3) The motor imparts a significant frictional/mechanical load on the
input being measured.
Maybe I'll find a use for this, or maybe I'll just pony up the $$$ for a
proper angle/rotation sensor. Let me know if anyone finds a use for
this.
Regards,
Dave
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Message has 1 Reply:
 | | Re: Using the Motor as a Tachometer
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| (...) Dave, this use of a motor as an input is fascinating! (How safe is it? Looking at some older threads, there seems to be a difference of opinions, or at least a non-consensus that it's safe...) I just hooked an 1x2 LEGO incandescent lamp up to (...) (25 years ago, 8-Aug-99, to lugnet.robotics)
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