More power (literally) for the HP-41, follow-up.

[Diego Diaz]

Hi all,

Just to keep track of the progress, here you are some details of this project advances.

Batteries arrived Tue. past week so I can finally build a "rudimentary" (and quite ugly) but functional prototype.

Once confirmed everything fits (tightly) into the battery compartment, back to the PCB drawing sw to design the final layout of the electronics and make sure the dimensions of the boards are as precise as possible to mimic the original battery holder.

Some technical details follows for those who might be interested: (you can jump to the pics in case you're not ;-)

The Power Pack (now officially designated as 82120D) is built using 3 PCB's. The outer (cover) one is 1.6mm thick, it is slotted on the top to allow the removal of the pack in a similar way as the original and sports the "82120D" part number.

On top of it (seeing from the natural position of the calculator), a second board, 0.8mm thick, will be firmly welded by 12 spots; this contains the electronics (USB-C charger, DC/DC converter, the "BAT" annunciator comparator circuit, connection terminals and the insertion safety switch).

Finally a third 0.8mm thick board will carry the LiPo battery itself and one 1Amp fuse. This board will be connected to the electronics board by 6 DuPont header&plugs.

A slot in this board (for the safety switch actuator) prevents it from being inserted the wrong way. However, even if someone manages to connect it to the headers in the opposite direction the the design foresee such circumstance and avoids any reversed voltage to reach the electronics.

The safety switch disconnects the negative terminal of the battery to preserve power when the Pack is not in use. If the user wants to charge the Pack out of the calculator just need to keep the switch pressed: a simple elastic band can do the job.

Last required parts have already been ordered (and shipped according to Mouser's email), and PCB's are in production (according to JLCPCB). Time to wait and see if all these pieces can finally be joined together and we get a new, up to date and reliable power source for our 41's.

All the best from the Caribbean!

Diego.

PS: Yes, there's still time to enjoy the sunny beaches. ;-)
   
   
   
   
   

[dmh]

Looks and sounds great, excellent work Diego!!!

Do you have any idea yet on cost and when these will be available to purchase?

[Massimo Gnerucci]

Way to go, Diego!
Eagerly awaiting...

[Didier Lachieze]

Very nice and clever design ! I’m in for a couple units.

[anetzer]

(06-29-2023 06:27 AM)Didier Lachieze Wrote:  Very nice and clever design ! I’m in for a couple units.

"+2 please!"

[rprosperi]

Thanks for the update, details and photos Diego, clearly some serious progress.

That last photo shows an unexpected part, however good to see after all these years!

Looking forward to availability, continued good luck (not that you need luck...)!

[HP-Collection]

Nice work indeed.
As I also use LiPos in my working machine, please +2 for me as soon as yours are ready to sell... just currious about your version.

Matthias

PS: What about your "new" module we heared about las Allschwil Meeting?

[Sylvain Cote]

(06-29-2023 05:53 AM)Diego Diaz Wrote:  Time to wait and see if all these pieces can finally be joined together and we get a new, up to date and reliable power source for our 41's.

I am ready, money is in the bank, house has been mortgaged!

(06-29-2023 12:40 PM)HP-Collection Wrote:  PS: What about your "new" module we heared about las Allschwil Meeting?

What! Where! a new module from Diego ? ... or are you talking about the MAXX module from Monte?

edit: since everybody is putting reservation number, I will take a minimum of 4 units when available.

[rocket.scientist]

Oooh! Nice work. I'm in for +2, please. I can't wait!

[David Hayden]

I'd be interested in 2 of these also. Thanks for doing this! I especially like the nice wide contacts for those finicky 41C battery terminals.

Dave

[twoweims]

This is wonderful news. Please put me down for two.

[Diego Diaz]

Hi all,

And thanks again for your overwhelming enthusiasm about this new project.

It is still in its very early stages and I cannot set a definitive date for the first production run or the final price. I will try to keep it as close to the €100 as possible with a top limit in the 150.

Next steps in my timeline are (after receiving the pending parts and PCBs):

Build 10 prototypes/pre-production units that will go to the 8 first users that have already shown their interest. One each, I'll keep one remaining unit to rum my own functional tests and the last one will run some (quite likely destructive) endurance testing. This will hopefully be by end July.

These units are basically intended for beta-testing to detect any design/building flaw(s), check real world behaviour, charge/discharge cycles, not foreseen safety issues, etc.

Gathering the reports and apply improvements/changes as necessary. Along Aug.

Order the parts for the first production run and setting the final price. Early Sep.

First production units ready to ship by end Sep. or Oct.

A number of circumstances may alter (delay) this estimation but I'll keep posting the relevant milestones as the project advances.

Notes on other comments of yours:
@Sylvain, Please, please, please, keep your house!! I couldn't forgive myself if you lose it because of my projects. :-D

@Matthias/Sylvain, I'm not really sure what "New module" are you referring to.

Sylvain, IICR (my memory is far from perfect :-), by mid 2021 I sent you a preliminary "Functional description" of a new design (codename MORPH) which never goes beyond the drawing board and was conceptually very similar to the MAXX module presented by Monte a few months ago: all ROM images already installed and selectable configurations on the fly.

Apart from this, I have not been working in other new module eversince.

@Dave, the battery terminals are still in my "concerns" list. The ones I've used in the prototype are IMHO too stiff, posing about 800gr force on the I/O block and hence in the plastic screw post which are renowned to be quite brittle.

The original alkalines holder springs pushed just some 350gr. So I'm trying to find some smoother contacts to keep this figure as close as possible to the original.

Again thanks for your comments and interest.

All the best.

Diego.

[tangdfx]

Just my personal opinion， Lipo battery is not safe for long term storage.

Corrently I use 4 N size Ni-mn rechargeable bettery.

[rprosperi]

(06-30-2023 04:51 AM)tangdfx Wrote:  Just my personal opinion， Lipo battery is not safe for long term storage.

Probably not a threat here - I can't imagine too many HP-41 fans are planning to purchase a cutting-edge, high-tech, €100 battery in order to store their 41 for any long-term. But, I suppose it's possible and could happen by accident.

Why do you think that Lipo is more dangerous than Ni-MH in this case? Swelling of the case?

[Ángel Martin]

Hola Diego,

Is it too late to get on the prototype list?

My three rechargeable battery packs are as good as dead wood on water, and I can't really afford more Lady N-Size batteries anymore :=(

Saludos,
Ángel

PS. Where's your Dorian Gray painting? You're looking younger every year!

[John Keith]

(06-30-2023 12:30 PM)rprosperi Wrote:  Why do you think that Lipo is more dangerous than Ni-MH in this case? Swelling of the case?

Li-Po batteries do have a reputation for catching fire. The majority of the fires are in high power density applications like scooters, and mostly in shoddy no-name products with poorly designed charging circuits. I would agree that small Li-Po batteries with conservatively designed chargers pose little risk.

[Sylvain Cote]

(06-30-2023 02:49 AM)Diego Diaz Wrote:  @Sylvain, Please, please, please, keep your house!! I couldn't forgive myself if you lose it because of my projects. :-D

OK, I would make sure that I do not overspend! LOL

(06-30-2023 02:49 AM)Diego Diaz Wrote:  @Matthias/Sylvain, I'm not really sure what "New module" are you referring to.

Me neither.

(06-30-2023 02:49 AM)Diego Diaz Wrote:  Sylvain, IICR (my memory is far from perfect :-), by mid 2021 I sent you a preliminary "Functional description" of a new design (codename MORPH) which never goes beyond the drawing board and was conceptually very similar to the MAXX module presented by Monte a few months ago: all ROM images already installed and selectable configurations on the fly.

Apart from this, I have not been working in other new module eversince.

Really !!!
I absolutely have no recollection of this email.
I just checked in my old emails and I am not finding anything on this.
I found these threads ...
2022-10 - custom 41C overlay
2022-09 - 41 bank switching document
2021-02 - on 82106A modules
2020-XX - several threads regarding questions for my Clonix/Nov presentation and on your HEPAX prototype restoration

Best regards,

Sylvain

[Massimo Gnerucci]

In queue since 2023-05-21...

[elinick]

Diego, I am a frequent lurker, but rarely post. I don't know if this helps gauge interest, but I too am very interested in such a product. - Evan <fades back into obscurity>

[Sylvain Cote]

(06-30-2023 02:36 PM)Massimo Gnerucci Wrote:  In queue since 2023-05-21...

Nah! different thread, does not count.