Mine also likes to sit in the middle of the driveway when a familiar car arrives, to force the driver to drive around him. If a stranger ever shows up in the same type of car as one of the familiar ones, he's gonna be toast.

 

Here's an interesting article. I wish he had followed up on it with another post.

http://ph-elec.com/archives/sensor-hacking-on-a-chamberlain-garage-door/

 

OK, back to the simple. How about a series of balls hanging from the ceiling which each one spaced to just touch the windshield of the vehicle you are driving when at the proper position. You could label or color the balls so you would know which ball to use for a particular vehicle.

I used a ball in my garage for that purpose where I ran the string through a pulley attached to the rafters and then to the top of the garage door. That way when the garage door was down the ball was pulled up and out of the way.

 

OK, back to the simple. How about a series of balls hanging from the ceiling which each one spaced to just touch the windshield of the vehicle you are driving when at the proper position. You could label or color the balls so you would know which ball to use for a particular vehicle.

I used a ball in my garage for that purpose where I ran the string through a pulley attached to the rafters and then to the top of the garage door. That way when the garage door was down the ball was pulled up and out of the way.

That would work.






But it doesn't have even one transistor.

 

According to some internet postings, it is not possible to simply put another pair of sensors in parallel with the first. Apparently, the transmitter sends a square wave signal to the receiver, which tells the controller that there is no blockage. My assumption is that if I had two sets in parallel, it would essentially be an OR gate, and unless both sensors were blocked, the garage door would close. I need to think about this some more.

What is the input to the controller? A digital signal? Could you send them through an AND gate so that they BOTH must report clear? A NOT gate or two (or equivalent circuitry) may be necessary dependent on the controllers input requirement. Also, has anyone considered the possibility of transmitter A triggering receiver B? Could this be resolved by orthogonally mounting the sensors? Or using separate carrier frequencies?

Hope you don't mind my brain blathering... If it's annoying - never mind!

 

How about a light-weight plastic strip pivoted on the door and actuating a cut-off switch if the strip touches the rear of the car?

 

A curb feeler, love it. But it doesn't help the driver put the car in the right spot.

Here's an idea. An ultrasonic detector determines that a car is approaching the front of the garage. This turns on several laser LEDs mounted on the ceiling, each one positioned as appropriate for each vehicle, all in a row. The driver pulls in until the appropriate laser spot is positioned on some "landmark" on the vehicle's hood or windshield.

Plenty of transistors in this baby!

 

How about an ultrasonic detector at the rear of the garage that switches on a red, yellow or green led (for example) calibrated to light when the appropriate car is the correct distance from the rear of the garage?

 

That would work.


But it doesn't have even one transistor.

Well, you could put a few blinking LEDs on each ball.

 

Each auto has an RFID card inside. When it enters the garage, it tells an MCU to measure the appropriate distance with an ultrasonic sensor to the car's front bumper. It overrides the garage door until the car is clear and illuminates an indicator light when the car is in position. Sensors, logic, transistors & resistors & LEDs, with an MCU thrown in for fun.

 

Each auto has an RFID card inside. When it enters the garage, it tells an MCU to measure the appropriate distance to the car's front bumper. It overrides the garage door until the car is clear and illuminates an indicator light when the car is in position. Sensors, logic, transistors & resistors & LEDs, with an MCU thrown in for fun.

Now, we're talking!