Electroluminescent Backlighting for Calculator Displays

[Paul Brogger]

Here is a description of a backlight modification to a TI-89 (graphic) calculator. Looks pretty cool.

I wonder if any of the -48 or -49 users (or those of any HP LCD calculator, for that matter) might be interested. Would someone hardware-aware comment on whether such an approach should be feasible on the HP's?

Thanks . . .

[Vieira, Luiz C. (Brazil)]

Hi;

I saw the EL Panel page and... I don't know, using an external power converter (EL backlight needs a bit more than a few volts to run) with separate batteries. I saw the TI86 photo and I wondered what was that small connector (left side, between two corners). After seeing the EL Panel page, I understood that would be the power connector. It means we als have to cut calculator's case so we can plug external P.S. for the EL backlight.

I have a disassembled HP48 in hands right now, and I am almost sure there is enough space between the HP48 LCD and the mainboard to insert the EL panel. What worries me is that the metal chassis closes both sides ot the LCD, so it must be also cut off to allow power supply connector to be accessed.

Any ideas?

[Katie Wasserman]

Daniel Hertrich (and others) have developed a backlight for the HP-200LX that will likely be availbale in kit form shortly. Read about it here:

http://www.daniel-hertrich.de/backlight/

[Vieira, Luiz C. (Brazil)]

Hi, Katie;

this is, indeed, a better solution. I'm not sure about the specs for both DC-DC converters, but I believe Daniel is a lot closer to portable equipment (how long would HP48's batteries last with an EL backlight?)

Cheers.