driveway sensor

[spindown]

I recently purchased a device to notify me if someone entered our driveway. It worked for 6 days and quit. I had another brand before but it was unreliable but lasted a little longer.
I want to be able to detect automobiles or ones on foot. I have hardwire capability to the driveway. Any ideas? Thanks Paul

[desterline]

Light-beam break detector?

[Mike]

Yes, use an infrared LED on one side and a CDS cell on the other.

[Lin Farquhar]

What about a low power laser module? Use a photo darlington transistor as a receiver and maybe even some logic to pulse the laser and check the receiver. You can put the laser on one side of drive, receiver on the other, or you can put both in one box and use a small piece of mirror on the other side.

[Chris Smith]

Lin<p>What part of West Australia are you from? <p>Perth?

[spindown]

When I went to electronet I got hit by a number of advertisements. I tried several times but could not find any thing about infrared circuits or detectors.
Can anyone direct me to site to learn about the infrared detectors used on yard lights? thanks to all how responded to my initial inquiry. Paul

[Michael-love-electronics]

Try these 2 circuits:<p>http://www.electronic-circuits-diagrams ... ckt3.shtml<p>http://www.electronic-circuits-diagrams ... kt19.shtml<p> replace the blue wire in circuit 1 by a photo_resistor(LDR).
When the laser beam falls on the LDR, Its resistance falls to 20KOhm which is act as short circuit to pin4 of the 555. While when the beam is barried the resistance of the LDR will be 1MOhm in dark which O.C. to pin4 thus the alarm is on.<p>Note: The alarm will stop as soon as the beam returns to the (LDR).<p>[ November 23, 2003: Message edited by: Michael Wahid ]</p>

[frhrwa]

try www.x10.com they have all sorts of sensors, remotes, etc.. I've used them for years without any problems, until I overload the circuits at Christmas...