🚀 go-pugleaf

In article <3719@whuts.UUCP>, ramesh@whuts.UUCP (RAMESH) writes:
> Could somebody on the net suggest to me the appropriate photodiode and
> IR LED to use for IR remote control systems. (The same type as used on
> remote TVs, VCRs etc.)
> 
> I tried some Radio Shack Phototransistors but were too slow to
> detect the modulation from my TV remote.
> Thanks for any help.

I went through this some process about a year ago, and got several 
helpful responses from the net (about speeding up bipolar phototransistors).  
However, nobody had the right answer which I eventually stumbled upon myself:
Most bipolar photdiodes and phototransistors have switching speeds on the
order of tens of microseconds.  Since the IR remotes use carrier frequencies
with clock periods of around 25 microseconds, this does not work too
well.

You need to use a PIN (Positive-Intrinsic-Negative) photodiode.  Radio
Shack does not sell any.  I used an SFH205 from Active Electronics, 
Framingham MA.  The Texas Instruments TIL413 has been used for similar 
projects in Byte magazine.

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