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How can I build a sensor that lights up an LED when my car is in the garage? Answered

I am thinking of using a garage door sensor to tell if the car is there, and activate and LED in my house. I don't know if I can make it work for this purpose. Does anybody have any ideas? 


Use a beam-break detector - there are LOADS of them on here.

Or mod one of the ultrasonic things you can get for cars.

If you want a pressure pad detector, beware ! They leak and fail.


Thanks for the tip about pressure pads. And it looks like beam break sensor will be the best fit. I didn't know I'd have to build it from scratch, but since I cant find any for sale I guess I'll just do that. Unless you know where I could buy one already made?

You CAN buy them - there'll be some on Ebay I bet, but failing that, a good electrical supply store will be able to supply an Omron, Mitsubishi, Cutler-Hammer or whatever unit.

Try asking for a "reflective opto" switch, and not a beam-break - the reflective opto will get you to screw a plate, that looks like the rear reflector of a bicycle on the wall, and point the switch at it. Anything passing between the switch andf the plate will trigger it.


I assume that by garage door sensor, you are referring to the safety sensor that is used to detect whether anything breaks the beam while the door is closing, and then reverses the door?

I don't know the exact details of the output produced of the receive side of the receiver part of the pair, but it is most likely something that could be easily interfaced to additonal circuitry that would turn on an LED while the car is in the garage (beam broken) and turns it off when the beam is not broken.

just get a small motion sensor and mount the wires to what room you want...then connect an led.........

but wouldn't that only detect motion, not the presence or absence of the car? And wouldn't any motion activate the sensor?

I was looking for pressure pads, but I can't seem to find any that would take the weight of a car. Do you know of anywhere to look for one?

Modify something like this? If you're trying to detect the actual car maybe a magnetic sensor or pressure pad?



A pressure switch seems perfect and simple, but where can I find one that is heavy duty enough to drive over?

I think garage door sensor will not will not be much useful to tell you if car is there or not. You can use ultrasonic sensors or LED reflective sensors.

By using these kind of sensors, you will not have to keep your car in a perfect position every time. Or you can use beam interrupt sensors ( an IR LED & a phototransistor ) to know the presence of your car.