Author Topic: ir led and ir pen  (Read 5610 times)

Offline noobzor

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on: February 07, 2009, 08:08:30 AM
ok so i build my first ir pen. i did this using an Infrared Diode. The diode has the same spec of the Vishay TSAL6400 but they differ in the angle of instenity(correct me if i'm wrong).

mine was 75 degrees and the TSAL6400 is 25 degrees.

tried Lee's project and Boojin's board all went fine but for my calibration. i can't seem perfect the calibration.

I've reached 55% tracking utilization still tracking was not efficient as on the video. What do you think is the problem? Is it my LED or do I have to increase my tracking utilization?

one thing, the shape of my diode is not the ordinary diode you can buy on radioshack. Its tip is not round as TSAL6400 does but instead it is a semi-square shape.


TIA



Offline benpaddlejones

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Reply #1 on: February 08, 2009, 12:46:10 AM
noonzor
Many IR-leds appear to have similar specs to the Vishay TSAL6400, but there are soem very specific diferenc etaht matter the most.

What IR-led are you using (data sheets?)

benpaddlejones :)


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Offline noobzor

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Reply #2 on: February 08, 2009, 04:32:02 AM
i don't have its data sheet but the seller brouhgt it up when i bought the diode on the shop. As i've mentioned above they have the same specs with TSAL6400 but differs in angles.

my diode has a 1.7V forward voltage, 940nM and 100mA and 75 degrees angle.



Offline benpaddlejones

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Reply #3 on: February 08, 2009, 04:55:42 AM
noobsor
The filter at the front of the Wiimote specificaly filters the light spectrum 940nm. You can have two different IR-Leds both with an average 940nm spectrum. However if the covered spectrum that makes up the 940nm average is too wide not enough 940nm will actually go through the filter to be tracked.

Its like trying to buy coke from a vending machine, that only takes $1 coins:
Buyer A
  • 4x 50c
  • 5x $1
  • 1x $2
Total $9
Mean/Mode = $1 (most common, based on whole coins)
Cans of coke = 5

Buyer B
  • 5x 20c
  • 2x 50c
  • 3x $1
  • 1x $2
Total $9
Mean/Mode = $1 (most common, based on whole coins)
Cans of coke = 3

Both buyers have $9 and a $1 average, but buyer A can buy more cans of coke!

I hope this helps you understand it is a little more complex than this but the concept remains.

Unfortunatley you have been mislead by your local eltronics dealer. More likely they don't fully understand the application and on face value both IR-Leds would have looked very similar.

This is why so amny swear blind their IR-Led is just as good, but it isn't till you look at the finer details in your case likely the IR-Dispersion chart, that you see the Vishay TSAL6400 (& 5300 identical dispersion) is teh IR-Led of choice for a reason.

Many months ago I purchased about 100+ IR-Leds from arround the Globe, only a few performed to the same standard. But the Vishay TSAL6400 won hands down as perfect average voltage, international availability and price (0.50cents each, cheaper in bulk).

benpaddlejones :)



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