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Old 08-09-2017, 07:45 PM   #21
hizzo3
 
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Re: Which red light changer?

At my old apt, they had a gate that would never open until one day I had my 10lb steel skid plate on my vstrom. Then on, it would open... If I had the massive hunk of steel.

The metal lines are where copper wire is laid... It is inductive. That means your magnesium case and aluminum frame is near invisible.

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Old 08-12-2017, 12:05 PM   #22
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Re: Which red light changer?

Not so fast, KenH.

I know the difference between magnetic sensors and inductive sensors. But the discussion is around if a magnet can help trip an inductive sensor.

A moving magnet absolutely does have an effect on an inductive loop. In simple terms, inductors resist changes in current (capacitors resist changes in voltage). A moving magnet is going to effect the current stored (and collapsing) in the inductor.

For me, the question is still; "is a strong magnet enough to have an effect on a traffic inductive loop.?". For sure, if you slooowly sneak up on the traffic loop the answer is no. If you move the magnet over the loop the answer is "well, maybe", but the environment is may not be controlled enough to really get a good result.

But, as mentioned earlier, I have a gate with inductive detection. I also have a rare Earth magnet that is about 1/4 the size of the one in the video below (they are dangerously strong!). I walked out to my gate, waved the magnet over the 'sweet spot' and..... the gate opened. No car, no motorcycle, etc. Only my body and a moving magnet. Okay, a magnet that you would never stick to your bike and if you did you may never get if off, but I still got a positive result.

Here is a quickie basic inductor tutorial and a demo on how pronounced the effect can be:


Quote:
Originally Posted by KenH View Post
Well, I suppose Google is too difficult for some.

Here. is info on all manner of detectors. You'll note that inductive sensors respond to a twitch of their electrical fields, not magnetic fields. There are magnetic sensors, but generally not used in roads due to endurance problems and other bad habits.

All these sensors really are are metal detectors. Really. No rocket science.

Want to learn how a metal detector works? Look up "metal detector". There are several methods, magnetism is one, but others use less energy and are more dependable, so magnetism generally isn't used for stop lights and gates and such. Otherwise, nonmagnetic metals would not be detected. Induction allows the detection of conductive materials, not just magnetic. Apparently induction vs. magnetic is where the confusion comes from.

There is a forum on inductive sensing on the Texas Instruments website.
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