Re: ss frame and metal detectors (traffic lights)

[Jan van de Wouw <Jan@xxxx>]

****MODERATOR NOTE**** This about wraps up this thread. We're getting into hair-splitting. . . . . .

Running the risc of going on on this for too long I would like to ad
something to this discussion

Gary wrote:

> For a loop of wire to "detect" metal, there must be motion.
> It is the car passing over/into the loop which generates a current in 
> the wire. This current is then sensed. Hence, it doesn't matter 
> where the bike stops. If it has enough metal to generate the 
> required current to set off the sensors, it will do so when the bike 
> enters the loop.

This is not entirely true:
there is a small current running through the loop continously,
generating a small magnetic field. The current through this loop is
monitored the whole time and doesn't change when the surroundings of the
loop don't change.

When a car or motor bike or even someone with a wheel barrow comes along
the metal (any metal, magnetic or not) will interfere withe the magnetic 
field created by the loop. because of this there will be a change in the 
current running through the loop and if it's within certain parameters
(higher or lower) it will notify the lights of the presence of something.

The statement on putting your bike near the loop-wire is true:
the current-change will be more noticable so you will be detected,
by just riding into the loop the changes will be filtered out as
spikes and the lights will not register you.

You can not compare a hand matal detector and those used for traffic lights;
only their principle of operation is the same, but the applications
are so totally different that the software for both "looks" for other
parameters that change. If you've ever used one; a metal detector also
detects metal when in a stationary position...

In conclusion; YES the SS-framed car WILL trigger the traffic lights.

Thanks for putting up with me ;-)

JAN van de Wouw
Thinking Different... Using a Mac...
Living the Dream... Driving a DeLorean...

#05141 "Dagger" since Sept. 2000

check out the Delorean-Files at:
http://www.deloreanfiles.nl/
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