Dave, the audio circuits dont need to handle 38kHz, 19kHz would be fine. Here's an interesting technique to achieve what the IR sensor would see as a 38kHz modulation, using 2 LEDs in anti-parallel being driven by the left AND right channels.
http://jumpjack.wordpress.com/2008/0...ote-control-2/
Follow the next few pages for a complete explanation on how its done. Alternately, there's a Windows application (also mentioned on Jack's pages) that automatically creates a modulated .wav file appropriate for 38 kHz transmission directly from sound captured from an IR module, on the fly.
I tried this, and it works, but the range is very modest. In fact, there are quite a few Android apps using this technique to make your phone work as a versatile timer/remote shutter for a DSLR.
While on the topic of Androids and pics, there is a free terminal emulator on the Android that works wonderfully with any project that can be given bluetooth capability. Would be great to set parameters, check debug/calibration values and so on. No need to waste a display (or controls, for that matter) on a project, if it is to be monitored only periodically. Endless possibilities, I think.
Regards,
Anand
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