Turning a cellphone into remote control

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jumpjack
Posts: 12
Joined: Mon Jun 09, 2008 1:26 am

Turning a cellphone into remote control

Post by jumpjack »

Hi,
I'm quite new to "infrared world".
I spent last two weeks experimenting with remotes, circuits, leds, lirc, cellphones...
I ended up in a very interesting result:
i was able to turn my nokia 6680 into a remote control... even if the phone does NOT have IR capabilities!! 8-)

It was possible just by connecting an IR led to the headest port, and playing a properly built WAV file.

Details about how to build such files are in my blog:
http://jumpjack.wordpress.com/2008/05/2 ... or-just-1/

This post only talks about using PC like a remote, but once you have the needed files, you can just use your phone to play them and control your device.

The really weird thing is that I actually needed ONE single LED rather than two as described in the article!
I can't explain it at all: does my phone play wave files at 38000 Hz frequency?!? Hos is it possible??? :eek:
If not... why same wave file does not work when played on another phone without stereo capabilities?!?

I used this schema to connect the LED to my phone, maybe it can be useful to figure out what is happpening here?

Image

(note that I did the image BEFORE discovering only ONE led is needed...)

It would be useful if somebody else could do similar tests with other phones.
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johnsfine
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Post by johnsfine »

If the wav file is at 38Khz (38000 Hz), then you would want only one LED.

I don't know why the design you found had two LEDs in opposite directions. Depending on the voltage range of the signal, two LEDs might serve to double the resulting frequency, or two LEDs might just act like one (the one in the wrong direction doing nothing).
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jumpjack
Posts: 12
Joined: Mon Jun 09, 2008 1:26 am

Post by jumpjack »

johnsfine wrote:If the wav file is at 38Khz (38000 Hz), then you would want only one LED.

I don't know why the design you found had two LEDs in opposite directions. Depending on the voltage range of the signal, two LEDs might serve to double the resulting frequency, or two LEDs might just act like one (the one in the wrong direction doing nothing).
Several guys demonstrated how 2 leds are needed to play a 38KHz tone using an audio card only capable of playing 20KHz signals:
http://www.hackint0sh.org/forum/showthread.php?t=35975
http://features.engadget.com/2004/07/27 ... e-control/

Griffin Technologies even patented this method years ago.

Same wav file works fine if played using TWO leds on my pc but ONE led on my nokia 6680, which has symmetrical audio.
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jumpjack
Posts: 12
Joined: Mon Jun 09, 2008 1:26 am

Post by jumpjack »

I published my tutorial for turning any phone into an universal remote control:

http://jumpjack.wordpress.com/2008/06/1 ... e-control/
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unclemiltie
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Location: Pittsburgh, PA

Post by unclemiltie »

there was a guy a while back on the iPhone boards talking about an app and some hardware that does this for an iPhone. I think he named it iCouchPotato or some such.
this JP1 stuff is a sickness!
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jumpjack
Posts: 12
Joined: Mon Jun 09, 2008 1:26 am

Post by jumpjack »

unclemiltie wrote:there was a guy a while back on the iPhone boards talking about an app and some hardware that does this for an iPhone. I think he named it iCouchPotato or some such.
yes, I'm in touch with him (actually I wouldn't have been able to complete my project without his help!)
My "add-on" to his project is that you don't need to build complex circuits: you just need a couple of LEDs, even for sampling your remotes :wink:
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