Engenharia Mestra de Sistemas Sociedade Ltda wrote:
>
> Hello, friends.
>
> I am trying to find a good IR led (and receiver, also) for remote control
> purposes. I heard about the TIL38, with a switched current of 2A (10
> microsecond pulses, 1 millisecond frame) or 100 mA continuous. I could not
> find these here in Brazil, though.
>
> I am sure some of you have already dealt with these components and know
> other options, as well as a good receiver and some good tips.
>
> Which makes the best detector, a phototransistor or an infrared sensor
> (those mounted in a smoked case) ?
>
> The application is a 'too close' sensor. I want to oscillate the led and PIC
> the reflected beam, reflected by a 'clear' (skin color) surface. I want a
> range around 8 to 10 inches. Do you think I will have to use extra lenses ?
>
> Thanks,
>
> Pedro.
>
> ______________________________________________________
> Pedro Drummond
> Engenharia Mestra de Sistemas / SP / Brasil
> Voice: 55-11-883.4799   Fax: 55-11-883.4926
> e-mail: mestra@u-netsys.com.br
> ______________________________________________________


One good source is Siemens:

T1-3/4 (5 mm bullet pkg) IR LEDs:
-------------------------------------------------------------
Hi power AlGaAs (880nm)         SFH484-2 and similar P/Ns
Hi power GaAs (940nm)           SFH415-U

The GaAs parts tend to have faster rise and falltimes.

Most IR LEDs will handle short pulses (microseconds) at currents up to
about 2 Amps provided that average current is within ratings.  Be
careful that your drive waveform never puts out long pulses, though.

For photodiodes, the world's most popular P/N is probably BPW34F, which
is an  IR filter 2 pin DIP.  For a lenses photodiode, consider the
SFH203 range, which has various suffixes depending on angular coverage
and filtering.

If you want to work with an integrated module, have a look at the
Hamamatsu S3599 or the Sharp IS471F.  These 4 pin devices require only
an external bypass capacitor, a resistor, and an LED to make a
modulated, EMI/RFI immune, sunlight immune sensor.  The unlensed
versions are quite cheap. To achieve your desired range, you can either
add a simple lens or boost the current drive to the LED with an external
transistor.

You can email me with further questions.
--

Paul Mathews, consulting engineer
AEngineering Co.
optoeng@whidbey.com
non-contact sensing and optoelectronics specialists