Car garage entry proximity sensor

[Cribey]

HI All,

I am wanting to create a sensor so that when the car enters the garage a sensor perpendicular to the car entry direction activates and a red LED goes on and stays on as long as the car is in the line of the sensor.

Once the car pasts the sensor (this means the car is safely in the garage and out of line of the sensor), the red LED turns off, and a green LED will go on for 10-15 seconds. The circuit then shuts off/resets.

What would be the best way to go about designing this circuit? I would like to use AA or a 9-volt battery or similar.

Thanks!

 

[crutschow]

You could use an IR (invisible beam) entry sensor on the ceiling that uses a retro reflector, which you could mount on the floor.
But I don't know if they are available with battery power.

 

[Tony Stewart]

Depends on your budget and electronic assy skills.

Most reliable has Tx on one side and Rx on the other side. at bumper height, which can share power with low current and 1 LiPo cell.

One method which has excellent immunity is like that used in TV remote controls with pulsed frequency bursts which are filtered to block;
• DC light (e.g. from tungsten bulbs sunlight)
• Continuous signals at any frequency
• Strongly or weakly modulated patterns from fluorescent lamps with electronic ballasts

A less reliable method can be made equality reliable by sinking the lens behind a matching 5mm D hole to attenuate any other light.
It can then be visible LED or invisible IR and pulsed for small duty cycle to reduce battery consumption on the Tx.
The Rx just needs to detect the pulse and stretch it with a diode & RC value and CMOS gate to act as a pulse stretcher and the LED indicator is ON.
When the pulses stop, by a blocked path the LED indicator turns OFF.
With this method the path by small 5mm tunnel can be made very precise or fairly loose and installer aimed by eyeball..
It can be made a sensitive to detect a 1mm object blocking the path or a finger size or bumper size merely by adjusting resistor values and hole depths.

IR Rx method https://www.mouser.com/ProductDetail/Vishay-Semiconductors/TSOP32338SS1V/?qs=sGAEpiMZZMvAL21a/DhxMry5nKn3biWwC6ykjkKFOq0=
IR Tx uses a IR LED and a simple chip with passive parts to generate the clock burst and rep rate like a CD 4060.

THe problem with reflective sensors is the reflectance is ambiguity of detecting the car and amplitude. of stray reflectance, but possible to resolve.

edit...
It's not a problem to indicate the Red Grn LEDs as you requested. using a one shot cct.

 

[Cribey]

Thanks crutschow and Tony Stewart for your replies.

Hmm, I thought it might be easier than that. Perhaps I can use a proximity sensor (ultrasonic module) so that when the car moves toward the sensor it lights up green when at the right distance into the garage.

OR

Again, perpendicular to the car, when the car reaches a certain point in the garage it triggers an LED to turn on for 15 seconds.

Thoughts??

 

[Tony Stewart]

If the car has a nice reflection back to the sender , that would be fine, but then the far wall is a bigger target and would also send back a reflection.
If it is just a single garage, you can get close to the car, but a double garage , no gaurantee.

 

[MikeMl]

G'Day Mate!

Post #10 of this forum thread shows the easy way to do it. (Read the entire thread)
The sensors I describe are cheaply available here. A garage door installer would have lots of old ones they remove when they install new garage doors.

 

[KeepItSimpleStupid]

If this is your car and garage, a tennis ball hanging from a string.

 

[MaxHeadRoom78]

You can get a spare part pair from anyone who stocks or sells Chamberlain G.D. openers, they are fitted standard now.
I assume they would also be fitted in your part of the world.
Max.

 

[Tony Stewart]

Tx pulser and Rx pair with short pigtails $23 https://www.amazon.com/Liftmaster-4...80626-4242232?ie=UTF8&*Version*=1&*entries*=0 ( THis is basically the $2 IR components in my link except in a nice housing and pigtail . )
You still need the one shot pulse detector in Mike's 555 IC circuit.

This is the same principle as my suggestion. It is the cheapest, most reliable, method.

Now the reason you need this should have been obvious up front, but it's not.

Other than an LED indicator of a car entering or leaving the garage,

what is the real purpose? resolution and accuracy?
This should be standard practice for any engineer, to have a spec.

If it is to precisely locate the edge of the vehicle, a dangling tennis ball will do but needs adjustment from car to car.

If your garage has a workbench like mine and only a few cm clearance at either end of being hit by garage door or hitting my tools, then please specify accuracy and real purpose.

For example, I once designed a method with IR transmission to detect a shopping cart nose rail, the direction it was going and if a case of beer was still in the bottom of the cart.
One could do the same for a car bumper and detect the direction the car was moving and if the bumper was parked within the safety zone. ( not too close or far. )

Then of course what cost? and ease of installation do YOU need/want?