Flow of Infrared Circuit

[WhyWhy]

Hi all,

I'm confusing the flow of this infrared circuit,can try explain to me ? Thanks.


Regards,
YY

 

[123jack]

https://www.edaboard.com/threads/299460/

 

[WhyWhy]

That is LDR sensor..

 

[wp100]

Hi,

You do not say what you are confused about ?

R1 and D1 are the IR led transmitter, R2 and D2 are the IR photo receiver ( arrows shown incorrectly as output, should be input)

The more IR light D2 receives the higher its output becomes.

RV1 is used to Set the level though U1 at which point the voltage from D2 turns U1s output on.

 

[WhyWhy]

Sorry i not mention which i confused about :=:roll:

1) When the more light to the IR light,The D2 receives the higher its output and then will send the output to the negative side or Positive side of U1?
2) From starting,did there any current pass through the V1 into the positive of U1 ?

Thanks.

 

[wp100]

Sorry i not mention which i confused about :=:roll:

1) When the more light to the IR light,The D2 receives the higher its output and then will send the output to the negative side or Positive side of U1?
2) From starting,did there any current pass through the V1 into the positive of U1 ?

Thanks.

Hi,

Here is your circuit in a simulator, using a trim pot as the output from the IR Receiver going to the negative input of the 324 / 741

When the IR receiver voltage is Above that of the Reference trim pot then the op amps output is low.
When the IR receiver voltage goes Below then the op amps output goes high as in the diagram below.

V1 will only pass a very small amount of current the +input needs, though I would never use 100 ohms for the trimmer pot, at least 1K or more is much better, a muti turn trimmer even better.

You can see more about op amp basics on this page https://www.allaboutcircuits.com/vol_3/chpt_8/3.html

Of course you can dispense with the op amp all together if you read the ir Recievers output into an Analogue Port and use software to compare against a reference voltage value.

 

[WhyWhy]

Thanks Wp100 for help,it's solve my question