Re: IR LED to repair remote control

On Sep 25, 3:57 am, Andrew <xxrag...@xxxxxxxxx> wrote:
Unfortunately my Logitech harmony 880 remote stopped working. When
pointing it into a digital camera, I can no longer see the IR LEDs
lighting up (there are two). Logitech tech support has confirmed that
the IR LEDs are probably dead, but they have been less than helpful.

[...] I bought [...] part number 276-142 [...]
The remote worked great [...] but [...] died again.
[...] I was wondering if I
could get a few pointers in trying to order some IR LEDs[...]
The wavelength of the emitter that worked from radioshack was 940nm.
On digikey I see that there are LEDs ranging from 860nm to 950nm.
[...] does that mean that I should stick with that
wavelength?[...]

And what ratings should I pay particularly close attention to when
trying to spec an LED for this purpose? I'm thinking a combination of
the highest pulse forward current and highest continuous current? For
that purpose I saw the LITE-ON LTE-5228A, digikey part no 160-1062-
ND. 250mW power dissipation, 3A peak forward current, 150mA cont
current, 7.2V reverse voltage, and 940nm wavelength. It seems to be
the highest ratings in all categories for the 940nm wavelength LEDs
digikey stocks, and is my top choice right now. It also uses a clear
package like the original emitters, if that even matters.

Any thoughts overall on the matter?

Measure it. Put a couple 1n4001 rectifiers in series with a 0.1 ohm
resistor, then operate the remote. View waveforms with an
oscilloscope.

Or just get DigiKey's hardiest IRLEDs (one of each wavelength),
salvage some LEDs from another cast-off remote.

Might help us to know if the failed LEDs failed open, shorted, etc.

Cheers,
James Arthur

.

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