I've just dived into an Arduino project with the about as much electronics knowledge as a blind mule (although isn't that the fun part of these boards?) so hope you don't mind me asking naive questions:
I bought a pair of IR led/receivers from SparkFun (I can't post the URL as it's my first post but a google on SEN-00241 will bring them up)
...with the belief that I could get them talking to each other. I know IR tends to modulate around 37k so thought I could switch these things off and on real quick, and pick up the flickers on the other side.
Reading a few of the post here makes me think this isn't the case. Although as I'm only trying to get one object to 'generally' listen to another (*) can I get away with some kind of hack?
(*) I just want one object to transmit a pattern, and the other to flash along to it.
So I guess I'm asking, how do these receivers work? Are they like any other photoresistor and change resistance when IR light hits them? I can't seem to get any change on the analog input.
The only way to find out is to read the data sheet on them. There are lots of IR receivers and they work in many different ways. So you need to say what one you have.
More specifically I'm attempting to customize two toys to allow one to 'talk' to the other. The 'transmitter toy' will send some kind of IR signal (either modulated or anything else that can travel successfully) while flashing another LED, the 'receiver toy' will receive it and flash a similar pattern.
Groove, what do you mean by transmitted state and background state? Would DC On and Off not create a transmitted/background state?
I'm guessing I can post a direct link now, the IR things I'm using are:
I've looked at the data sheet but can't yet decode how that converts to understanding...
Think of the receiver a bit like an AM radio.
You tune the radio to a particular frequency, and even though there are transmissions of other frequencies (maybe even of a higher power), your radio will only "playback" to one station you want.
The receivers you linked are like your radio antenna - they will "pick up" (ie respond to) any IR transmissions, whatever the frequency, even DC.
To make your circuit more sensitive to just one set of frequencies, you need some sort of filter tuned to that frequency. This is demodulation.
By background state he means IR from sunlight and room lighting. This can be bigger than the signal.
As you are wanting this to operate at a decent range you are better off using a IR receiver with built in amplifier. Something like this:- http://uk.farnell.com/vishay/tsop1136/photodiode-ir-receiver-36khz/dp/4913024
Then you modulate (flash) the IR LED and turn those flashings on an off to get data. This is how remote controls work. The modulated signal allows the receiver to filter any static IR signals from lights.
The IR sensor you posted is of little use to you in this application.
'Transmitter' using basic IR Led (like the one I've got?) flashing at a set frequency (e.g. 38k) using code, with a 'Receiver' using an IR detector such as the one you mentioned.
And while I'm here (virtually) ... how does the extra pin work? VVC, Ground and ? I'm guessing a bit of internet research will answer this one.
Hi again. I hope it's alright to bump this thread rather than stat a new, it's still about the IR project.
So I've gone and got myself some modulated IR receivers. After blowing the first one (didn't realise they changed the pin config across makes!) I've managed to get something that looks like it should do the job... I've been following this thread for support: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1176098434
So far I've not managed to set off a dip large enough to get the pulseIn to trigger. Looking at the changes in voltage when pointing a TV remote at the receiver I get a dip of about 0.5 (from 4.8 to 4.2)... how can I amplify this? Is it just a matter of changing the resistance somewhere in the circuit or is this the issue, Grumpy_Mike, you mentioned with the need for amplification?
Also, just to save my sanity... does the fact there's any change at all with the voltage from the IR Receiver's Out pin mean that it's picking up a modulated IR signal? I've tried pointing a simple torch in there and nothing changed to I'm hoping that's the case.
