Red LED displays

[Jim Horn]

LED technology has come a very long way since the days of HP's LED calculators in the 1970s. So, since my June 1975 HP-25 electronics has died, I considered re-engineering it to use higher efficiency LEDs and CMOS circuitry to get more performance and many days of use on a battery charge.

But that is not to be. Seven segment displays that will fit are apparently no longer available from *any* source I've been able to identify. The world has moved on to LCD, OLED and other ideas. While Avago (HP => Agilent => spinoffs) still makes small 5x7 dot matrix displays, they won't fit enough digits in the case - and cost a small fortune anyway.

So the original display will have to be used. At least when combined with CMOS and a modern battery chemistry the charge duration will still be greatly increased. At least the battery circuitry won't fry the electronics. And a 49 step memory will be greatly expanded too.

If anyone is aware of good displays for this, please let us all know!

Many thanks -