looking for ideas for driveway alarm sensor

[Mr X]

hi, i'm new at forums,read a lot of them never posted. my problem, my driveway is about 500 feet long. i live in the country. i would like to know when someone enters my driveway, even if they are just turning around. there are too many false alarms with motion sensors and infra-red beams, animals, etc. so i have been looking into 'Demand-Actuated Traffic Signals'
but i'm having trouble locating any decent information. any information would be appreciated. also any links on how to use inductors would be helpfull also.
thanks and have a great day.
Mr X

 

[hjl4]

Here's what I found via google (go figure),

https://www.humantransport.org/bicycledriving/library/signals/green.htm

There are plenty more links on google, if you would of searched for
'Demand-Actuated Traffic Signals' .

Have fun.

 

[zachtheterrible]

I don't know what could possibly false trigger an IR beam, as long as it is put high enough so animals won't walk through it, unless they're kangaroos :lol: Birds??

The way a traffic light works is there is a piece of wire wrapped in a circle I'm not sure how many times, but when a car drives over it, the metal in the car changes the inductance of the coil. Unfortunately for you this would necessitate saw-cutting your driveway if it's concrete or blacktop.

 

[Mr X]

driveway alarm

Hey Thanks to both of you for your imput, I do appreciate it.

I found the same thing on google myself, but I need more. How would you activate a buzzer or led or light when a car passes over a wire in the ground? What voltages do I start with, I don't know where to begin with the electronic end.
Its pretty neat here on the property I live on, there are three of four deer that I see almost every night, during the summer they feed on the left over apples and pears that have fallen to the ground. thats the problem with infra red.
Thanks again.

 

[jbeng]

What Zach described is often known as a vehicle loop detector. It's basically a metal detector with loop of wire embedded in the roadway (or in your case, driveway). The loop of wire forms an inductor which controls the frequency of an oscillator. When a vehicle passes over the loop, it's metal content changes the inductance of the loop, which in turn changes the oscillator frequency. Additional circuitry detects the oscillator's frequency change and energizes a relay to change a stop light, open a gate or in this case, sound a bell or buzzer. They're also used to count vehicles to analyze traffic patterns. Try a google search for vehicle loop detector. Also, a search for LC oscillator will help you understand their operation.
JB

 

[Mr X]

thankyou very much this is the information i've been looking for.