Using Garage Door Sensors as alarm sensors

[Liquid_Squelch 0]

I have a crazy idea, and wanted to know what I'm getting myself into, if anything at all.

 

My house is located on a corner, and we get cars parking on the blind side of the house at all hours of the day. I would love to know when there is someone parked outside the house, and have my DVR log an alarm at that time. My thought was to go out and get a pair of those sensors you put in an automatic garage door install so that you know if there is anything in the path of the closing door. I was thinking that maybe I can put the beam side on my fence, and the 'bounce' side of the sensor across the street (or maybe a small mirror across the street so I can peg two locations on the side of the house by bouncing the beam across the road).

 

Does this sound like something that would work? Of course, I would need to set the alarm so that the beam would need to be blocked longer than x seconds to flag parked cars and not passing cars.

 

Has anyone attempted this yet, or am I just better off going with an outdoor PIR ?

 

Thanks for the help.

[Soundy 1]

I can't see any TECHNICAL reason that wouldn't work. You might need to have it trip a relay, and have that switch the alarm inputs on the DVR...

 

From a logistical angle, keep in mind that most of these actually have a beam on one side and sensor on the other, so you'd need to get a wire to the far side of the road... plus, the beam might become too diffused at that distance, especially if you're bouncing it back from the other side of the road.

 

There ARE designs that would work, designed for longer distances, for this but I don't think a standard off-the-shelf garage door sensor is suitable.

[shockwave199 0]

Do you have cameras in place? Why not just point one in that direction? You can monitor who's there, and with motion detection/alarm mode enabled, the dvr will record comings and goings as well.

[Liquid_Squelch 0]

There ARE designs that would work, designed for longer distances

 

Soundy, can you point me to one of these designs? Even if I need to talk to a neighbor to borrow power from her house, it might still fly. As long as the alarm contacts are in my yard I should be ok.

 

I can't use motion for this because the cars come up to the curb and stop. There are cameras installed. I found just how many people decide to sit on my curb by look at playbacks. I need something that shows there is someone there, not moving for an extended period of time. I figured if a beam was broken, then there is someone out there.

 

I'm also figuring if I can put the transmitter and receiver on my property, and bounce it of a center point across the street, I will be able to cover 2 areas where a car may be waiting with the same two sensors.

 

Maybe I am Googling the solution wrong too. What should I be searching for?

Thanks again for the help.

[ljarrald 0]

how good are you at DIY?

you could make a 'beam' that won't be 'diffused' at a long distance and that can be bounced off a mirror at the other side of the street.

 

you just need a lazer pointer, a few other bits and bobs and decent knowledge.

[Soundy 1]

Laser pointer DIY would probably be your best bet. Most sensors use simple IR LED setups with a simple lens to tighten the beam to cover 15-20'. You're talking about probably 80-100' by the time you get across the road and back.

 

Try this page for a start: http://www.electro-tech-online.com/electronic-projects-design-ideas-reviews/33205-laser-beam-break-detector.html

[Liquid_Squelch 0]

I am all for building my own solution. I took digital circuits in college and have basic knowledge on electrical circuits (would need to dust off some old info )

 

 

The Ultrasonic Range Finder looks great! I think that something that would sense an object at X distance away or less would indicate a vehicle parked outside. If the sensor is at max range, then there is no one parked.

 

There wouldn't be a need to add a timer circuit or power the far end of the sensor, which would be required to operate any other method.

 

Anyone try these ultrasonic sensors for alarm triggering? Low voltage, low current, and I should be able to load up enough resistors for a Normally Open or Closed position when the voltage is just right to indicate an object at curb distance.

 

Here is the kit from sparkfun http://www.sparkfun.com/products/639

And one from MaxBotix: http://www.maxbotix.com/tutorials.htm

 

Now I just need a way to make it weather proof! The weather proof items from SparkFun are $99US, not cheap.

[camera-newbie 0]

Isnt the sparkfun kit only good for 255 inches per the page you linked to -- limiting it to 21 feet give or take?

[Liquid_Squelch 0]

I am interested in knowing when cars are parked along my curb line. From my fence, the curb is 13' away. So any car parked along the line would be 13' - 20' away from the sensor. Anything greater than 20' would possibly be a car driving along the street, so I am not interested in catching those events.

 

I wonder if I can just run the Analog out to my alarm contacts with a resistor that will only pass enough voltage to latch the alarm at 13' or more. If the sensor cuts out at 21', I should worry about anything above that.

 

Thanks again for the help

[camera-newbie 0]

Interesting.. Let us know how it turns out!