On 2015-May-30, at 8:19 AM, tony duell wrote: > >> JOOI, does anyone know when Panaplex 7-segment displays started going the >> way of the dodo, to be replaced with LED displays (and, on the back of >> that, what were the advantages of a Panaplex-type display over an LED one?) > > It would appear that in the early 1970s LEDs were very expensive. I have been > looking at the > HP5930x HPIB units and in many cases the status indicators (power on, > listening, etc) are > filament bulbs + driver transistors. I can think of no advantage to using a > filament bulb in this > application other than possibly cost. The 59304, which has a Panaplex display > and therefore > the HV supply to drive it, uses neon bulbs (NE2 sort of thing) as status > indicators.
And the annoying and inconsistent use of incandescent bulbs for the power indicator and optical tape detector in the 9830 . . when the main display is LED.
