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Subject: 
Re: Inductive sensor?
Newsgroups: 
lugnet.robotics
Date: 
Tue, 15 Feb 2005 18:41:08 GMT
Viewed: 
853 times
  
In lugnet.robotics, Dan Novy <dan@flashfilmworks.com> wrote:
    Hey, sensor gurus, is there a way to create a sensor that will sense
inductively, as in "wrap a wire around another wire and have the RCX
tell you when current is flowing in the other wire?
Hello!
I work with these kinds of things, and will try to make a few suggestions.

Assuming the signal to detect is DC, there would be only a very short pulse on
the detecting line if a transformer (as You describe) is made from the two
lines, no signal would be present after that initial pulse.

A Hall element could be used to detect the magnetic field generated by a DC
current.

If the current was alternating, any coil could be used to pick it up (your basic
radio transmission, really) as long as the signal is strong enough.

By inductive sensor, usually a sensor is meant, where the current behaviour of
an AC voltage applied to a coil is used to detect the presence of metallic
objects in the vicinity of the coil.

Now to the solution:
One way to detect DC could be to make a "magneto-mechanical" sensor:
Wrap the wire around an iron rod with something isolating in between, point the
rod at a touch sensor, and if the polarity and number of loops is properly
adjusted, the thus produced solenoid could activate the touch sensor as current
flows in the line to be sensed. Description here:
http://www.detroitcoil.com/PAGES/How%20A%20DC%20Solenoid%20Works1.pdf
Hope this helps!
Olof



Message is in Reply To:
  Inductive sensor?
 
Hey, sensor gurus, is there a way to create a sensor that will sense inductively, as in "wrap a wire around another wire and have the RCX tell you when current is flowing in the other wire? (19 years ago, 15-Feb-05, to lugnet.robotics)

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