10 Apr
2001
10 Apr
'01
9:36 a.m.
I've started messing around with a GRiDPAD 1910 I
got a couple of years ago. Works fine on AC using
the brick that came with it, but the two battery
packs I got with it are dead. They won't take a
charge, either in the machine or connected directly
to the brick (they have a socket for this). The specs
printed on the batteries list 12 volts, 1Ah. I opened
one of the packs and the contents look very much like
10 AA batteries.
I'm wondering if I can replace the contents of the
battery pack with 10 AAs. The specs printed on the AC
brick say it produces 17.25 volts at 2A. If I replace
the contents of the battery pack with 10 AAs, I figure
I'll get around 15 volts. Anybody want to hazard a
guess as to whether this will work?
Thanks,
Bill Sudbrink
10 Apr
10 Apr
10:22 a.m.
On 10-Apr-2001 Bill Sudbrink wrote:
I've started messing around with a GRiDPAD 1910 I
got a couple of years ago.
I just got my hands on a 2360SL. Do these fit under the 10 year mark?
the SL has a 386 in it, so i wonder...
Anyway, do you have any good bookmarks about pen-based GRiDs? I've been
googling for an hour now, and haven't come up with much.
-Philip
10:59 a.m.
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5:23 p.m.
Bill,
It will probably work since the charging voltage of the battery is
certainly higher than the 15 volts that you would get from using alkaline
or carbon-zinc batteries.
But why take a chance? Take the battery pack to Batteries Plus or one of
the other battery rebuilders and have them replace the dead cells with new
cells. They can take it apart and remove the old cells and weld the straps
and terminals back onto the new cells and reassemble the pack and make it
work exactly like the original battery. FWIW I insist on the Japanese made
Sanyo cells, I've had VERY good luck with them. Don't let them stick you
with some no name Chinese or Mexican made crap.
Joe
At 02:36 PM 4/10/01 -0400, you wrote:
I've started messing around with a GRiDPAD 1910 I
got a couple of years ago. Works fine on AC using
the brick that came with it, but the two battery
packs I got with it are dead. They won't take a
charge, either in the machine or connected directly
to the brick (they have a socket for this). The specs
printed on the batteries list 12 volts, 1Ah. I opened
one of the packs and the contents look very much like
10 AA batteries.
I'm wondering if I can replace the contents of the
battery pack with 10 AAs. The specs printed on the AC
brick say it produces 17.25 volts at 2A. If I replace
the contents of the battery pack with 10 AAs, I figure
I'll get around 15 volts. Anybody want to hazard a
guess as to whether this will work?
Thanks,
Bill Sudbrink
11 Apr
11 Apr
10 a.m.
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2:29 p.m.
At 08:00 PM 4/11/01 +0100, you wrote:
Tony's right. You should have the battery in place when trying this.
You'd probably be safe leaving the battery out if you used a power supply
with the output set at a safe voltage (~ 1.2 to 1.5 Volts/cell) but don't
try this with a standard charger. They're seldom regulated and you could
fry something. Leaving the dead battery out and trying to run a HP 2xC
calcualtor on the charger alone is THE biggest cause of dead HP 2xC
caculators.
Bill,
It will probably work since the charging voltage of the battery is
certainly higher than the 15 volts that you would get from using alkaline
or carbon-zinc batteries.
Some machines use the battery as a shunt regulator -- that is to say they
rely on the fact that the voltage across the battery pack, even when
charged from a supply _capable_ of giving out a higher voltage, will be
limited. This is one reason why many HP and TI calculators may be damaged
if you connect the charger without a battery pack in place.
For the original poster, if you insist on using normal primary batteries
(1.5V each), I would start with only 8 of them in series, which should
give you 12V. I would not put 10 in. I have seen devices made with a
battery holder that will take 10 AA cells, and which are supplied with 2
dummy batteries (plastic rods the size of a AA cell, with metal contacts
at the end that are shorted togehter). If you use primary batteries you
use 8, and the 2 dummy batteries to fill up the empty slots. If you use
NiCds, you use 10 of them.
I am told that some HP calculators (the Woodstock HP21 series, for
example) can be damaged if you put primary batteries into the battery
pack. Now, I know how the Woodstock PSU should work (it's a little
transformer-based transistor oscillator with regulation taken from one of
the outputs), and I don't see why it wouldn't regulate properly at 3V
input rather than 2.4V input. But I certainly am not going to risk it :-)
FWIW I don't recommend it but I've run Woodstocks at 3 VDC and even a
little above. A FULLY CHARGED GOOD NiCad will often put out up to 1.55
volts/cell when they're new therefore a new Woodstock battery pack can have
up to 3.1 VDC.
Joe
-tony
1:59 p.m.
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4:59 p.m.
At 11:59 PM 4/11/01 +0100, you wrote:
I would be careful using anything above 1.2V/cell. I've seen machines
(the HX20 is one such) were there are 4 NiCd cells (nominally 4.8V, of
course) connected to the +5V line. And that's the _only_ regulation in
the machine.
Hmmm. How do they charge the battereis? 5 vdc isn't enough to charge 4
NiCads. Do they take them out and charge them outside the circuit.
From what I remember, the Woodstock PSU outputs a +ve Vss (about
+6.something voltes), a -ve bias supply and a lower +ve supply for the
display driver. The first output can't be less than the battery voltage
(It's a switching converter -- if the transistor is turned off all the
time, the Vss output is effectively connected to the battery by one
winding on the transformer). The same might apply to the display output
(which is lower, but still around 4V IIRC). I doubt very much if the
circuit will have problems running on 3V input.
However, I have heard that Woodstocks don't like 3V batteries. And to be
honest, even though I can't see why there'd be a problem, I am not going
to try it. All the chips in the Woodstocks are HP-custom and
unobtainable, so I have to preserve all I can.
I've never tried to run a Woodstock off of primary batteries so I don't
know if there's a problem with that or not. I have run them off of
regulated power supplies set at 3 V with no problem although I usually set
the supply to about 2.4 volts. I'm guessing that perhaps primary batteries
won't supply enough current for the Woodstock. They have an LED display so
current draw is a bit high (~150Ma). The other odd thing that I've noticed
is that is you have to have more current available or it won't start. I
have to set my PS up to about 250 to 300 Ma if I remember correctly before
the Woodstock will come on. After that the curerent drops to about 100 to
150 ma.
Joe
Some machines use the battery as a shunt regulator --
that is to say they
rely on the fact that the voltage across the battery pack, even when
charged from a supply _capable_ of giving out a higher voltage, will be
limited. This is one reason why many HP and TI calculators may be damaged
if you connect the charger without a battery pack in place.
Tony's right. You should have the battery in place when trying this.
You'd probably be safe leaving the battery out if you used a power supply
with the output set at a safe voltage (~ 1.2 to 1.5 Volts/cell) but don't
Now admittedly, the machines that do this generally use CMOS chips which
are reasonably forgiving about mild overvoltage. But still I'd not want
to risk it.
No, I don't think so. At least not a series problem. However the Spice
and Woodstock chargers will not supply enough current to operate the
calculators without the batteries.
The problem with the HP 2xC models is that the RAM is connected directly
to the battery in order to keep the Continous memory alive. When you remove
the battery and try to run the calculator off the standard charger you're
putting up to 18 volts directly into the RAM. Poof! There goes all the
magic smoke! AFIK this is only a problem in the 2xC models since they are
they only only models that connect the circuits directly to the battery
(and the chargng circuits) and not through an internal power supply.
The charger
try this with a standard charger. They're
seldom regulated and you could
fry something. Leaving the dead battery out and trying to run a HP 2xC
calcualtor on the charger alone is THE biggest cause of dead HP 2xC
caculators.
Is this the case with HP 3x machines (Spice/Spike) as well? circuit and battery pack seems to be electrically
identical, and the
machine's PSU is similar. In any case, I am not going to risk it.
Of ocurse in the -C (continuous memory) models, there is a backup feed
from the battery pack to (one of) the power pins on the RAM chip.
Normally, the battery voltage (+3V) is lower than the running voltage
(+6V-ish, from the switching coverter circuit), so it's OK. But plug the
charger in without the battery and that line will rise to about 10V (and
there's almost no load on it to pull the output down). That is going to cook
that RAM chip.
Exactly. That's why there are so many 2xC models around that have a
display but no memory, not even the X, Y and Z registers.
I have a nice bench PSU -- 0-30V, 0-10A. I use that for testing machines
with the battery pack removed -- set to 1.2V/cell of course. This seems
to be as safe as using the original battery.
It's even safer IMO since you can set the current limit low enough to
prevent doing any damage even in the event of a short. I have a small 0-20
volt 400 Ma HP supply that I use for testing all my calculators.
I am told
that some HP calculators (the Woodstock HP21 series, for
example) can be damaged if you put primary batteries into the battery
pack. Now, I know how the Woodstock PSU should work (it's a little
transformer-based transistor oscillator with regulation taken from one of
the outputs), and I don't see why it wouldn't regulate properly at 3V
input rather than 2.4V input. But I certainly am not going to risk it :-)
FWIW I don't recommend it but I've run Woodstocks at 3 VDC and even a
-tony
12 Apr
12 Apr
9:20 a.m.
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11 Apr
11 Apr
4:48 p.m.
Some machines use the battery as a shunt regulator --
that is to say they
rely on the fact that the voltage across the battery pack, even when
charged from a supply _capable_ of giving out a higher voltage, will be
limited. This is one reason why many HP and TI calculators may be damaged
if you connect the charger without a battery pack in place.
Hmmm... Are you are saying that running the machine from the
AC brick with no battery in place will damage it? If this is
the case, then the damage is done. I've run it for 20+ hours
with no battery in place. The diagnostic screen indicates that
the machine is aware that no battery is present.
For the original poster, if you insist on using normal
primary batteries
(1.5V each), I would start with only 8 of them in series, which should
give you 12V.
A little creative wiring and, voila! it works with 8... for about 10
minutes and then goes down. Diagnostic screen indicates battery
voltage of 10.6 volts with 8 new AAs.
12 Apr
12 Apr
9:09 a.m.
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