power adaptor/charger



#3

what do I need for the "vintage series" HP35,45,55,65
AC or DC output ? Voltage? max current?

(Of course I could buy an original charger on eBay such as the 82002A I guess, but I have almost 20 different chargers for old dead cellphones, so I want to save me that expense.)


#4

The charger for these machines has 2 outputs (with a common -ve connection on the centre pin).

One output is 4.2V regulated, DC. This is used to run the calculator logic when the charger is connected.

The other output is constant _current_, 55mA with an open-circuit voltage of about 15V. Note this is not the same as a 15V adapter, it must be constant current since it's directly connected to the NiCd battery when the charger is connected. This is used, of course, to charge the battery.

On the 65 and 67, the card reader sense amplifier chip is connected to the battery connections. You need to take care not to damage that if you use a non-standard charger. This chip is HP-custom, and the one in the 65 is supposed to be more fragile (electrically) than the one in the 67 and later machines.

There's an ASCII-art schematic of the HP charger over in the Articles Forum. And a hand-drawn one on the HPCC schematics CD-ROM (at the 'back' of every classic-series schematic IIRC). If you want to build something, that would be a good starting point. The transistors are all pretty generic types, nothing critical.

But I doubt any other charger will work without damage!


Possibly Related Threads...
Thread Author Replies Views Last Post
  HP-67 charger Marcel Samek 3 1,093 11-22-2013, 10:45 PM
Last Post: Marcel Samek
  What power adaptor does an HP-65 use? Robert Morton 3 939 09-30-2012, 02:32 PM
Last Post: Kees Bouw
  WP 34S USB flash adaptor arrived Harald 53 7,707 04-29-2012, 11:03 PM
Last Post: Dale Reed
  HP-67 wall charger Wytnucls 2 835 04-19-2012, 10:13 PM
Last Post: Dan W
  HP 97 charger Harald 2 784 03-30-2012, 02:01 PM
Last Post: Harald
  Which charger for a35 Matt Agajanian 3 922 03-23-2012, 02:58 AM
Last Post: Marcus von Cube, Germany
  Aristo M85 -- What charger? Gene Wright 9 1,901 11-03-2011, 04:56 PM
Last Post: Mike (Austria)
  HP97 charger Olivier De Smet 5 1,111 09-20-2011, 06:53 AM
Last Post: Paul Berger (Canada)
  HP-67 AC Charger Ángel Martin 6 1,375 06-25-2011, 07:31 PM
Last Post: Trent Moseley
  N Size Cell Charger Gerry Schultz 3 948 06-17-2011, 12:14 PM
Last Post: Gerry Schultz

Forum Jump: