Report and a belated note of appreciation

[Pimpom]

Earlier this year, I posted a question about the directional
accuracy of branded IR LEDs, the Vishay TSAL6100 in particular.
This was because I had been having alignment problems with
no-name LEDs bought from local shops. I'd found that such LEDs
project their beams in directions several degrees off their
physical axes. The problem was exacerbated by the fact that my
project involved _two_ parallel IR beams with an LED and a sensor
housed in the same box. Two such boxes face each other with the
beams going in opposite directions. Like this -

LED >>>>>>>>>>>>>>>>>>>> Rx

Rx <<<<<<<<<<<<<<<<<<<< LED

One of the responses to that thread was by Steve Noll who'd done
actual measurements of the TSAL6100's behaviour. The results
corresponded quite well with the idealised curves on the
datasheet. Armed with that knowledge, I ordered the LEDs from the
Indian branch of Farnell. When compared with the no-name LEDs,
the difference in range and ease of alignment was dramatic.

With the no-names, I could barely get reliable reception at 4m
outdoors - after some tedious fiddling with the relative
positions of the two boxes. With the TSAL6100s, I could simply
place the boxes on the ground, roughly facing each other, and I
consistently got a solid link without any further adjustments at
more than 10m. With a little bit of coaxing, they still performed
reliably at 25m.

The sensors were part of an important project that's to be used
at regular intervals. I'd already used them on one occasion with
the crappy LEDs but dearly felt the need for an upgrade. The
improved sensors were a huge success at the second event.

Thanks, Steve.

 

[SoothSayer]

Yes, and for some hundreds of dollars, there is a seminar about sensors
and sensor technology somewhere.

I just got an email about it from NASA Tech Briefs. It's at The
Sheraton, Boston, MA Oct 10-12 $1295 for all three days.