IR Beam Break Sensor

Thread Starter

grcshekar71

Joined Oct 8, 2021
7
Dear Experts there !

Can you please help me with circuit diagram and components for an IR Sensor (Transmitter and receiver) which can set digital pin to high / low when the beam between transmitter and receiver is broken. I would like to use this to detect an object in middle of the door so that I can stop the motor from running when an object is in middle of the door. Distance required between transmitter and receiver is about 48 INCHES
 

MaxHeadRoom

Joined Jul 18, 2013
23,939
You can get Chamberlain style garage door sensors on Ebay for around $15.00.
What type of controller do you have so far, if any?
What motor? Is this an existing garage door control?
 

ElectricSpidey

Joined Dec 2, 2017
1,972
Are you SURE you want to build? There are plenty of pre-made units that can work for what you want...everything from cheapo units up to professional alarm units.
 

Juhahoo

Joined Jun 3, 2019
250
DO you do this as a hobby to learn things, or just to get it done?
If latter, buy it ready made. They cost very little. Then modify if you need.
 

Sensacell

Joined Jun 19, 2012
2,919
You will find that 48 inches is more difficult than you might expect.

The signal-to-noise ratio is poor, ambient light forms a significant source of interference.
Modulating the light beam is a typical solution, but many sources of ambient light are also modulated.

A cheap and cheerful solution is to use a cheap red laser and a simple phototransistor.
The drawback is the critical alignment required when using a narrow laser beam.
 

Thread Starter

grcshekar71

Joined Oct 8, 2021
7
You will find that 48 inches is more difficult than you might expect.

The signal-to-noise ratio is poor, ambient light forms a significant source of interference.
Modulating the light beam is a typical solution, but many sources of ambient light are also modulated.

A cheap and cheerful solution is to use a cheap red laser and a simple phototransistor.
The drawback is the critical alignment required when using a narrow laser beam.
At Least 15 Inches
 

Tonyr1084

Joined Sep 24, 2015
6,460
You can get Chamberlain style garage door sensors
I've messed with GDO units, trying to make them work without the safety beam sensor. Bypassing the beam sensor connection with a dead short or an open did not make the unit operate. Trying a variable resistor didn't work. Nothing I did would work without the actual safety beam sensors installed and operating. As I looked further into the issue it became apparent to me that they were operating on a given frequency with a given value (unknown) current. For the GDO to operate the signal had to be within set parameters. Trying to use GDO Safety Beam Sensors will probably be more difficult than to opt for something pre-made. At least for me it would. I don't know enough about the sensors to be of value or help for you. I just wanted to point out that safety beam sensors from a GDO might not be an easy solution. The last Chamberlain I had used back pressure to reverse the door. That meant if the door encountered so much force while closing it would reverse and fully open. It was from before the safety beam arrangements.

I've seen red lasers used as a triggering method for sensing a broken beam. Since the beam and sensor would be live all the time, exterior light might not be quite so problematic. But I've not messed with such circuits in the past so I could be wrong. My thinking is a strong light source falling on a photo transistor or some other device might be strong enough to perform the task required. However, back to the safety beam sensors, my MIL (Mother-In-Law) had a west facing garage door. In the afternoon when the sun was shining in on the sensor during a particular time of the year, the door would not close. You had to HOLD the button till the door was fully closed.
 

MaxHeadRoom

Joined Jul 18, 2013
23,939
The last Chamberlain I had used back pressure to reverse the door. That meant if the door encountered so much force while closing it would reverse and fully open. It was from before the safety beam arrangements.
The latest doors I have fitted have both, my older one is back-pressure version only..
 

MaxHeadRoom

Joined Jul 18, 2013
23,939
I've messed with GDO units, trying to make them work without the safety beam sensor. Bypassing the beam sensor connection with a dead short or an open did not make the unit operate. Trying a variable resistor didn't work. Nothing I did would work without the actual safety beam sensors installed and operating
Here is a Youtube explanation of the pulse required.
 

Tonyr1084

Joined Sep 24, 2015
6,460
it became apparent to me that they were operating on a given frequency with a given value (unknown) current.
Here is a Youtube explanation of the pulse required.
Thanks. Yes, I knew there was some sort of pulse.

Both my GDO's are Genie. I'm assuming a similar pulse.

Back when I was messing with it I wasn't trying to operate a door. Rather I just wanted to see if I could trigger some sort of event. But the point here to grcshekar71 is that you would need some sort of detector to detect that pulse. Simply putting Safety Beam Sensors (SBS) won't yield anything very useful without having a way to detect the timing of the low going signal and its period.
 

Juhahoo

Joined Jun 3, 2019
250
Place the receiver behind the IR screen to filter all other wavelenghts off. Install the receiver sensor inside a longer tube to get rid of the external light all together. Install and align the transmitter towards the tube, place the receiver away from all other light sources. Use narrow beam IR transmitter diode.

I still recommend buying ready made unit, check how it's done and hack it as you like. Much faster easier and cheaper than sourcing all parts. Circuit diagrams you find online for free if interested to build it from scratch.

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Last edited:

MaxHeadRoom

Joined Jul 18, 2013
23,939
Place the receiver behind the IR screen to filter all other wavelenghts off. Install the receiver sensor inside a longer tube to get rid of the external light all together. Install and align the transmitter towards the tube. Done.
That is not for the Chamberlain etc versions where the ms pulse occurs?
 

Reloadron

Joined Jan 15, 2015
6,220
arduino mega 2560
Since you are taking that route and in the interest of DIY (I would run with a garage beam) you may want to consider buying a cheap LASER diode and receiver.

LASER Transmitter Modules

LASER Receiver Modules

With the 5 Volt transmitter I would place a maybe 47 Ohm 1/2 watt resistor in series with it. If this is going to be outdoors or in high ambient light I defer back to a garage door safety IR system which as pointed out can be had very inexpensive. I have used the above linked indoors with normal ambient light and they worked fine. I forget if the receiver goes Hi or Low when the beam is broken so just code accordingly.

Ron
 

Thread Starter

grcshekar71

Joined Oct 8, 2021
7
Since you are taking that route and in the interest of DIY (I would run with a garage beam) you may want to consider buying a cheap LASER diode and receiver.

LASER Transmitter Modules

LASER Receiver Modules

With the 5 Volt transmitter I would place a maybe 47 Ohm 1/2 watt resistor in series with it. If this is going to be outdoors or in high ambient light I defer back to a garage door safety IR system which as pointed out can be had very inexpensive. I have used the above linked indoors with normal ambient light and they worked fine. I forget if the receiver goes Hi or Low when the beam is broken so just code accordingly.

Ron
Can I please have circuit diagram for this
 

Sensacell

Joined Jun 19, 2012
2,919

These have a fairly wide beam angle, the signal you receive will be very very small.

Try placing these inside a cardboard box to exclude all ambient light, spaced apart at your desired distance.
measure the resulting photocurrent with a DMM, then open the box under normal room light and measure again.

This horrible SNR (signal-to-noise ratio) is the problem.

This is going to require some fairly complex circuitry to get working reliably.
 
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