5 May
2001
5 May
'01
12:45 p.m.
Hi, I've got an HP-21 that is missing the battery pack. Does anyone know
which pin is plus and which minus when you look at the calculator from the
back, with the AC adapter plug facing up? I can probably synthesize a
battery pack with a couple of AA NiCd cells but wouldn't want to hook it up
backwards.
There are two contacts at the "back" of the battery box for the cells and
it would be useful to know this info ...
--Chuck
5 May
5 May
1:22 p.m.
In reverse shouldn't hurt it, just as if you put AA cells in a radio and
they were backwards. Transistorized equipment is polarized to work so my
guess is that it wouldn't hurt it. Charging them backwards might though.
-----Original Message-----
From: owner-classiccmp(a)classiccmp.org
[mailto:owner-classiccmp@classiccmp.org]On Behalf Of Chuck McManis
Sent: Saturday, May 05, 2001 7:45 PM
To: classiccmp(a)classiccmp.org
Subject: + and - on HP21 calculator?
Hi, I've got an HP-21 that is missing the battery pack. Does anyone know
which pin is plus and which minus when you look at the calculator
from the
back, with the AC adapter plug facing up? I can probably synthesize a
battery pack with a couple of AA NiCd cells but wouldn't want to
hook it up
backwards.
There are two contacts at the "back" of the battery box for the cells and
it would be useful to know this info ...
--Chuck
1:45 p.m.
Ah but the battery box is designed to take the molded HP battery unit,
which plugged into the back, rotated down and latched into the top (see
<http://www.home.mcmanis.com/hp21-back.jpg> for a picture. Since it would
be "impossible" to connect it backwards its possible the HP engineers
dismissed that possibility and said fine this will never come up.
--Chuck
At 08:22 PM 5/5/01 -0500, you wrote:
In reverse shouldn't hurt it, just as if you put AA
cells in a radio and
they were backwards. Transistorized equipment is polarized to work so my
guess is that it wouldn't hurt it. Charging them backwards might though.
2:21 p.m.
I assumed that it needed a molded battery unit but the main gist was that if
you made your battery pack and polarized it wrong that it probably wouldn't
hurt it.
-----Original Message-----
From: owner-classiccmp(a)classiccmp.org
[mailto:owner-classiccmp@classiccmp.org]On Behalf Of Chuck McManis
Sent: Saturday, May 05, 2001 8:45 PM
To: classiccmp(a)classiccmp.org
Subject: RE: + and - on HP21 calculator?
Ah but the battery box is designed to take the molded HP battery unit,
which plugged into the back, rotated down and latched into the top (see
<http://www.home.mcmanis.com/hp21-back.jpg> for a picture. Since it would
be "impossible" to connect it backwards its possible the HP engineers
dismissed that possibility and said fine this will never come up.
--Chuck
At 08:22 PM 5/5/01 -0500, you wrote:
In reverse shouldn't hurt it, just as if you
put AA cells in a radio and
they were backwards. Transistorized equipment is polarized to work so my
guess is that it wouldn't hurt it. Charging them backwards might though.
6 May
6 May
8:55 a.m.
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