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Topic: IR sensor circuit problem (Read 4506 times) previous topic - next topic


I would like to do a IR reflective sensor so I constructed this circuit......Why does the circuit no function at all???
What's wrong of this circuit???


.Why does the circuit no function at all???

Lots of possible reasons:-
1) Because you have not wired it up correctly.
2) Because you have the IR source too far away, try it at a distance of less than 10mm
3) Because you are not blocking it with something opaque to IR.
4) You have not specified what sensor that it, you have just drawn it as a transistor.


Also maybe the IR diode and the photo-transistor aren't designed to use the same wavelength frequency?



Are D and Q in one package?


Just given the circuit diagram then nether do we.
What you need to do is to post a photograph of how you have wired it up along with the code you are running.


If it's not working, it's about 90% probability you have the thing wired wrong. The other
10% is they sold you a bad part.

Also, note, as G_M indicated in his first post, those small packages sense properly over only
a very short range, a couple of mm. The data sheet will say.

Now, the larger devices will sense over a much longer range, but the following one probably
has pickup to the side directly from the Led. Usually there is a light baffle in between Led
and pickup device.



This is my pcb design.......


Dec 09, 2012, 07:57 pm Last Edit: Dec 16, 2012, 12:34 am by Folderol Reason: 1
You've shown the receiver as being a diode, but the spec sheet says it's a transistor! Is the Collector connected to +5V?

Does the output stay at zero (I'm rather expecting it does) so increase R2 to something like 1M

If it stays at or near 5V, then either it is surprisingly responsive and picking up stray IR, or you've damaged it.

What are you using as a reflector?


This is my pcb design.......

No it is not, it is a schematic. It is a different schematic than you said you were using in the first post.
I asked:-
What you need to do is to post a photograph of how you have wired it up along with the code you are running.

If you are going to keep changing your story and refusing to cooperate with requests you won't win many friends here.


This product is for 3v,
Your sketch indicate 5v....


Good luck!

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