HP82143A Powering a 41 _Extend Your HP41_

[TallKey]

When is the below statement true?

   

Tested and failed

Above is from Extend Your HP-41, Nov 1985, p30.

[rprosperi]

(05-20-2023 08:07 PM)TallKey Wrote:  When is the below statement true?

Be sure Flag 55 is set, which enables the Printer. Possibly, when not set, the 41 f/w doesn't look on the bus to enable it? Just a wild guess...

Flag 21 also enables/disables the printer in some more subtle ways, could also be related?

[TallKey]

(05-20-2023 09:48 PM)rprosperi Wrote:  

(05-20-2023 08:07 PM)TallKey Wrote:  When is the below statement true?

Be sure Flag 55 is set, which enables the Printer. Possibly, when not set, the 41 f/w doesn't look on the bus to enable it? Just a wild guess...

Flag 21 also enables/disables the printer in some more subtle ways, could also be related?

Testing the theory:

Printer attached, ON.
41CV ON (no battery power for weeks)
MEMORY LOST
CLX
FS? 55
YES
FS? 21
YES

Pull battery pack, display fades to blank.

Several minutes pass, install batteries, display contents are displayed (no ON press), but that is expected behavior.

Flag 21 set or clear, no change to battery pull or to the battery install, IE as above.

Found no difference which is ON first, the 41 or the printer.

Additional testing of the flags with the printer attached:
Printer OFF/ON, 55 and 21 are set.

Summary is am unable to replicate Dr. Mier-Jedrzejowicz printer HP82143A powering the 41.

Haven't near dead batteries to test if the printer supplies some power and then clears the BAT flag

[Sylvain Cote]

(05-20-2023 08:07 PM)TallKey Wrote:  When is the below statement true?
Tested and failed

I tried it on an HP-41CV without batteries and it does not work, even when the printer is connected to a power supply.
But, the USB-Power module from Diego Díaz does work perfectly, follow this link to see how to create one.
Sylvain

[TallKey]

(05-21-2023 01:02 AM)Sylvain Cote Wrote:  I tried it on an HP-41CV without batteries and it does not work, even when the printer is connected to a power supply.
But, the USB-Power module from Diego Díaz does work perfectly, follow this link to see how to create one.
Sylvain

Thanks Sylvain. Have seen the post you shared, haven't a module to give to this cause.

Now have reason to wonder about modifying a peripheral, like a card reader vs a module

Referring to the contacts as 5 GND (-) and 1 BAT (+)

I can see you might cause problems with the battery pack installed with a now powered card reader supplying 5V.


---------------
| 11 9 7 5 3 1 |
[12 10 8 6 4 2 ]
--------------

Someone please rate the idea of modifying a peripheral, like the CR vs a module for USB I/O power:
Will work, might work, or just don't

[Diego Diaz]

Hi all,

This post was supposed to be published in a few weeks, but since the subject has been brought up this could be a good place/moment to share.

More power (literally) for the HP-41.

Over the years I've seen several ideas (some of them really ingenious) to provide a more convenient, rechargeable, up-to-date battery pack or some type of powering connection for our beloved HP-41s.

I've done a few myself, USB cables and refurbished 82120A with NiMH cells. The first one has the problem of filling one I/O port, while the second offers a very limited capacity and requires the use of the HP transformer.

Also, most of these solutions were just DIY projects and didn't manage to reach a 'production' status and fulfill the needs of the user's community.

Last but not least, the alkalines LR1 type cells are becoming both scarce and expensive and, regrettably, still are the cause for a number of corrosion cases.

In the last couple of months I've been working on a new project to overcome these problems and offer a rechargeable Li-Po battery pack which will, hopefully, become a serious replacement for the alkalines and the venerable 82120A.

The specs of this new power pack are as follows:

- Same dimensions as the original battery holder.

- Same insertion extraction procedure.

- Slightly higher power than the alkalines; 7,000mW vs 6,000.

- Rechargeable while in use via USB-C type connector, thru the existing charging port; or while removed.

- Steady voltage output of 6v. 

- Dual output protection: Insertion switch and fuse.

- Up to 1A continuous current. Well enough to keep the Card Reader running as needed.

Materials:

The pack includes a 2,000mA/h 3.7v Li-Po battery with built-in charge/discharge protection circuit.

USB-C charger with current and voltage limiter IC.

Step-up DC-DC converter slightly modified to provide an output of 6v.

A safety microswitch to disconnect the negative terminal when the pack is removed from the HP-41. This prevents the terminals from accidentally getting short circuited if they both touch a metal surface.

Anyhow (since we've learnt a few lessons from Chernobyl), a 1Amp fuse is connected to the positive terminal. The fuse is placed in a way that is easily accessible so most anyone with average solder skills can replace it if the need arises; and two spare fuses will be provided with the pack.

Seriously, if you blow three fuses, please stay away from any electrical source; for your own safety. :-)

Two drawbacks:

- The principle of operation of the DC-DC converter keeps the voltage in the nominal 6v until the battery is discharged, hence no 'BAT' indicator.

- Some USB-C connectors are built with a metal casing, this type of connectors must not be used with early HP-41C including the golden ball contacts.

So far only the concept and dimensional drawing have been done. First serious test to be run by mid next month, and (if it works as expected) first ten units will hopefully be ready by end July or early August, and before you ask, tag is expected to be around one hundred.

Comments, questions and suggestions are always welcome.

Best wishes from the Caribbean.

Diego.

   
   

PS. The 3D render is by all means inaccurate ans messy

[Massimo Gnerucci]

(05-21-2023 04:47 AM)Diego Diaz Wrote:  Comments, questions and suggestions are always welcome.

Great, great news (as usual) from you Diego!
Already in queue for a couple of them.

[rprosperi]

Greetings Diego! As usual, you bring interesting and good news to those of us that still keep working 41's at hand.

I am interested in getting a couple of these, after Massimo's 2 and Sylvain's initial dozen.

As the BAT annunciator cannot work, what is the expected end-of-charge behavior, unit simply does not appear to power-on, or lighter LCD contrast, etc.?

[MeindertKuipers]

(05-21-2023 04:47 AM)Diego Diaz Wrote:  Comments, questions and suggestions are always welcome.

Really good stuff Diego, looking forward to get more details. And if you need help in testing you know where to find me

[Diego Diaz]

Hi all,

And thanks for your enthusiasm and your kind words.

To cover the original post question, at first glance the schematics in the 82143A service manual does not show any evident way for the Printer battery that can provide power to the HP-41.

The Vcc line is connected to the port, and Q3/CR1 connect it to Vp (5v) for the internal logic circuits in the Printer; but this won't provide any usable voltage for the bipolar power supply IC in the calculator and the BAT line isn't even wired in the connector.

I don't have an 82143A with me to check any further, but this statement seems to be either an error or a feature in some early Printers that was later removed.

Regarding the new power pack design, the lack of BAT annunciator is my main concern currently.

Not that this will render the unit useless but it will be great to have it back, so I'm working on a couple of mods that may recover such function.

Limited real state in the battery well is indeed challenging to include more components; but hey! if won't be funny if it was easy. ;-)

All the best.

Diego.

[Sylvain Cote]

(05-21-2023 12:20 PM)rprosperi Wrote:  I am interested in getting a couple of these, after Massimo's 2 and Sylvain's initial dozen.

A dozen is a little exaggerated but I will surely take several, like 4 to 6.

[AndiGer]

(05-22-2023 02:28 AM)Diego Diaz Wrote:  Regarding the new power pack design, the lack of BAT annunciator is my main concern currently.

Diego,

Maybe Tony‘s experience may be of help?

https://www.hpmuseum.org/forum/thread-12...#pid171807

Andi

[TallKey]

(05-22-2023 02:28 AM)Diego Diaz Wrote:  I don't have an 82143A with me to check any further, but this statement seems to be either an error or a feature in some early Printers that was later removed.
Diego.

Diego, the guidance the author provided is of limited to no use (based on my experiments with 2 82143A printers) and from a post above.

The quote in post #1 is from the second edition of the book.

Perhaps the earliest printers had had power over I/O, and if true, then I expect they'd be both coveted and well known.

[Ángel Martin]

(05-21-2023 04:47 AM)Diego Diaz Wrote:  Comments, questions and suggestions are always welcome.

Can't wait to get three of those, never too soon!
Best,
ÁM

[Garth Wilson]

Every boost switching regulator I've worked with takes a pretty substantial amount of quiescent current (ie, with no load), which would drain the battery quickly.  You might be able to have it shut down when the calc is off; but I'm wondering if the lower (non-boosted) voltage will be enough to retain memory and keep the clock running, and whether the regulator can be brought up quickly enough when the calc is turned back on.  I really don't know.  The output capacitor could be big enough to keep the calc going for around five seconds, after which the regulator would have to be brought back up for perhaps a few milliseconds to charge it back up and then go back to sleep, if you could have a micropower timer handle that.