Subject: Re: HP48sx Infra-Red diode wavelength?
Lines: 7

sorry, dont know the wavelength, but according to the "HP 48 I/O
Technical Interfacing Guide" (HP, June 1990), the part number of the
IR LED is either an NEC SE303A or an HP HEMP-3301, and the photo-
transistor is an EG&G VATEC VTT 9112.  maybe you could get the
wavelengths easier with the part numbers in hand...

-matt


Subject: Re: Hewlett-Packard LED's
Lines: 8

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


Subject: Re: Hewlett-Packard LED's
Organization: HP Network Measurements Div, Santa Rosa, CA
Lines: 32

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.