how to make IR beam breaker ?

[Qasim Khokhar]

i want to build an ir beam breaker circuit.Can any one help me ? i want to turn on Led if IR puls exist and turn Led of if IR plus is absent .

 

[pinout]

Start as simple as possible.
Power the IR led via a series resistor connected to a battery. Choose a current at a level upto that quoted by the typical current specified in the data.

I would then select a photo transistor and connect this to a logic IC. Depending what you have a CMOS 4000 series device would be a good starting point.
use a pullup resistor from the photo transistor collector and connect the collector+resistor junction to the CMOS input.

Test this circuit and once operational you can follow on with LED driving.

 

[jiripolivka]

Start as simple as possible.
Power the IR led via a series resistor connected to a battery. Choose a current at a level upto that quoted by the typical current specified in the data.

I would then select a photo transistor and connect this to a logic IC. Depending what you have a CMOS 4000 series device would be a good starting point.
use a pullup resistor from the photo transistor collector and connect the collector+resistor junction to the CMOS input.

Test this circuit and once operational you can follow on with LED driving.

I am confused what exactly you want. A "breaker" is a device that breaks or interrupts the beam. What my colleague has described above is an IR beam indicator. When an IR beam hits the detector, it lights a LED.
To break the beam, you should add a mechanical device to the LED circuit that will break the beam from getting further. You can use a relay or a small electromagnet that inserts a metal flag into the beam to break, or to stop it.

 

[Qasim Khokhar]

Start as simple as possible.
Power the IR led via a series resistor connected to a battery. Choose a current at a level upto that quoted by the typical current specified in the data.

I would then select a photo transistor and connect this to a logic IC. Depending what you have a CMOS 4000 series device would be a good starting point.
use a pullup resistor from the photo transistor collector and connect the collector+resistor junction to the CMOS input.

Test this circuit and once operational you can follow on with LED driving.

would you please explain circuit give in following link

https://www.electroschematics.com/6005/ir-beam-breaker/

 

[pinout]

would you please explain circuit give in following link
https://www.electroschematics.com/6005/ir-beam-breaker/

Just to confirm I am trying to help with something that detects when an IR beam is broken, which is how I understood your question.

My method was to try and get you understanding the most simple IR source and IR detector type circuit, but simplicity comes at a cost!
The simple circuit will be sensitive to stray IR light which can be from an incandescent light bulb or more likely sunlight. This will be much greater than our IR generator power and will swamp our simple detector.

What your link describes is a way to get round this problem. It is not 100% perfect but does work very well and was developed by the TV industry to make TV remote controls work with stray IR.

Basically the IR beam transmitted is pulsed on and off at 38kHz, the received IR is sent to an integrated circuit built into the IR receiver and this tries to look at only IR at 38kHz. It is AC coupled and filtered to look at only the light pulses switching at around 38kHz. This removes the interference from light bulbs and the sun which are only low frequency.
Beam broken is now 'no 38kHz IR received' and beam not broken is a '38kHz IR signal received'.

Other conditions could be detected as the beam broken, e.g. IR transmitter is off, or the IR beam is misaligned, but this could also be considered 'fail safe' if it being used for intruder detection and makes it more 'tamper proof'.

Hope that helps but come back if you have further questions.

- - - Updated - - -

Looking around that web site I found
http://www.electroschematics.com/6239/invisible-alarm/
This is similar to my simple beam break detector, i.e. suffer from stray IR. the detector diode also needs to be an IR one or have a filter to avoid it also detecting daylight!!!

 

[jiripolivka]

Now I understand - you need not a beam breaker but a beam break detector. Then the above advices are fine.

 

[pinout]

Here is a link regarding 38kHz modulated IR as a beam break detector using an Arduino.

https://www.righto.com/2010/03/detecting-ir-beam-break-with-arduino-ir.html

This is posted just for your information and future use should you want to investigate a microcontroller solution.
I haven't read it, but it seems interesting enough to share, but just ignore if not of interest.