h a l f b a k e r yNot so much a thought experiment as a single neuron misfire.
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I reecently purchased and, after a great deal of difficulty, installed, a remote controlled gate opener and closer for the large wrought iron gate at the entrance to my driveway. I also purchased with it a rod which is intended to be buried in the driveway INSIDE the house compound, and the way it operates
is that it senses when a vehicle goes over it (magnetically I guess) and then triggers the gate opener, letting guests leave without needing to have the gate opened for them.
Unfotunatley, nearby buildings/people are providing enough interference that it is triggerring the gate to open, ruining th ewhole security aspect of the whole thing.
So i was thinking instead of building a weight-based switch which would be trigerred when a car goes over it. I thought that the basic idea would be to have a steel box, open at the top, maybe one and ahalf times the width of the car mounted sideways in the driveway. Then, there might be 8 or so coil springs, maybe a couple of inches high, mounted at various spots in the box. then there would be another steel plate mounted on top of the box, with edges that overhang th ebox below (exactly like the small top of a shoe box. Mounted on each end of the top would be switches which would connect when the top lid was depressed. there would only be a small movement, say a half inch.
anyhow, other ideas welcome: I am sure it has already been invenetd but i can't seem to get the wording right to get any meaningful results on Google.
Loops & Loop Detectors at GateDepot.com
http://www.gatedepo...ccessories_loop.php
A wire loop - like those used for traffic lights - might make more sense. No pun intended. [phoenix, Dec 30 2009]
driveway alarms
http://www.driveway...way-signal-kits.htm
yep, they're out there [lurch, Dec 30 2009]
[link]
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//So i was thinking instead of building a weight-based switch which would be triggered when a car goes over it. |
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You should try and figure out what is happening with the incorrect triggering and fix that. Otherwise, it sounds like the driveway will be inaccessible for several months while you tinker with your design. |
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I saw something like this in a Benny Hill video. There was a big black rubber button out in the driveway, which he stomped on to open the garage door (and "accidentally" hoist up a woman's skirt). I assumed that it was a common item in England, and that it was designed to be driven over by a car. |
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But maybe it was just something he made up. |
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Rubber hose across across the driveway. Sealed at the far end; when you run over it the air pressure inside jumps up and dings the bell in the service station, which causes the service station attendant to come running. |
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Or, at least, that's how it worked about forty years ago. |
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yes, but does he live near a service station ? |
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Will a Faraday cage block capacitance sensing ? |
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At the risk of appearing pragmatic, I would call the
company that sold you the gizmo and tell them it's dud.
It's meant to work properly. |
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If you were determined to build your own, I'd start with a
cheap metal detector - one that has an LED that comes on
when the signal passes a preset threshold. Power it from a
transformer instead of batteries, connect the LED output
to your gate controller. Put the detector in a robust non-
metal box set into your driveway, and adjust the
sensitivity until a car triggers it but random noise doesn't. |
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Or just ask your valet to let guests out, like he's meant to. |
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ask the people at Mcdonalds they have a sensor that wont go off unless a motorbike or larger piece of metal sits over it. |
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A $19 webcam and some open source free software. |
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