nichols@en.ecn.purdue.edu (Scott P Nichols) (03/14/91)
Does anyone know the wavelength of the IR LED's that the HP-48SX uses?
I'm guessing about 806-820 nm, but I'd greatly appreciate an answer from
someone who knows exactly.
Thanks in advance.
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/vv\ \ __Insight from Oregon...Scott P. Nichols
_____/ \ ~~~~~~~~~~~~~~~~ (nichols@en.ecn.purdue.edu)akcs.brentlz@hpcvbbs.UUCP (Brent Ellzey) (03/15/91)
An October 1987 HewlettPackard Journal article on the infrared link suggests that the LED frequency is 940 nm. This article goes on to say that the "infrared link uses 32.768 kHz as the infrared modulation frequency". The article goes into further details of the infrared coding, etc. that I truthfully don't fully understand( I'm an aerospace engineering undergrad, not an EE :-) See if your library has a copy. Brent Ellzey E10140197@ccit.arizona.edu
darrylo@hpnmdla.hp.com (Darryl Okahata) (03/16/91)
In comp.sys.handhelds, nichols@en.ecn.purdue.edu (Scott P Nichols) writes: > Does anyone know the wavelength of the IR LED's that the HP-48SX uses? > I'm guessing about 806-820 nm, but I'd greatly appreciate an answer from > someone who knows exactly. I don't know the wavelength of that LED, but the "HP-48SX Technical Interfacing Guide" contains a schematic that uses either the HP HEMP-3301 or the NEC SE303A LEDs. For the HP HEMT-3301 (which I assume is the about the same as the HEMP-3301 -- or "HEMP" could also be a typo), the specs are: Ta=-40 deg C: Spectral peak @ ~920nm (and is ~1.35 times that of the peak at Ta=25 deg C) 50% of peak @ ~910nm & ~935nm Ta=25 deg C: Spectral peak @ 940nm 50% of peak @ ~920nm & ~960nm Ta=85 deg C: Spectral peak @ ~955nm (and is ~0.65 times that of the peak at Ta=25 deg C) 50% of peak @ ~930nm & ~980nm Note that "Ta" = "ambient temperature". -- Darryl Okahata UUCP: {hplabs!, hpcea!, hpfcla!} hpnmd!darrylo Internet: darrylo%hpnmd@relay.hp.com DISCLAIMER: this message is the author's personal opinion and does not constitute the support, opinion or policy of Hewlett-Packard or of the little green men that have been following him all day.