Metal proximity detection

Archiver

Hello all,

I'm trying to find out what sort of sensor I would need to use to
detect the proximity of a large metallic object (say, umm, a car...)

I am trying to design a new driveway monitor. The current one uses
a motion sensor which picks up everything from my dog to UPS trucks,
and everything in between...

I would love to make it metallic-sensitive so I could eliminate the
dogs, cats, deer, groundhogs, etc from setting it off.

Somewhere through my purposeless searches on the internet in years
past, I seem to remember there being a metallic object sensor... Some
sort of proximity sensor... that has a field of detection that is
fairly large(several feet)... Does such a device exist?

In the end, I would like to totally build a monitor system based on
a stamp to take care of this problem for me...

Thanks!

Archiver

In a message dated 11/12/2003 2:37:25 PM Eastern Standard Time,
brad@g... writes:


> I am trying to design a new driveway monitor. The current one uses
> a motion sensor which picks up everything from my dog to UPS trucks,
> and everything in between...
>
> I would love to make it metallic-sensitive so I could eliminate the
> dogs, cats, deer, groundhogs, etc from setting it off.
>

Could you put a metal detector in the center of your drive way?

Sid


[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

It's possible...

I just found a link that is sort of interesting:

http://www.smarthome.com/7170.html

It shows a sensor that appears to be contained in PVC piping... Not
sure exactly whats within the pipe, but I suspect its some sort of
large ferrite rod with a coil on it... My guess is that the control
unit senses the changes in inductance when a vehicle drives over it...

Unfortunantly, I'm not much for figuring out analog-ish circuits.
Digital is what I know. lol.

Anyway, I'm going to keep digging. Thanks!


> Could you put a metal detector in the center of your drive way?
>
> Sid