Finally I got my HP-67!

[Artur - Brasil]

I Love this machine blinking The leds while computing!!!
Would give a treasure to Discover what is going on with so many dots, slashes etc blinking.
As usual, a Li-ion cell Phone and charger circuit took place of old Ni-MH batteries and a simples cell charger instead off HP wall charger.
See my work!
Now, two 41, one cassete drive and one hp-il printer, and the 67 on Li-ion batteries.
Pics show charging process. I was afraid of destroying the case trying to cut it on side. So, I attached The circuit to the battery door, by inside. Just release it tô get acces to charger conector.
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[Craig Bladow]

That's awesome! How did you connect the battery to the calculator's power terminals?

[Craig Bladow]

Now we need some one to make a battery case, similar to the case that holds 3 AAAs, made for the classic calculators and available on TAS (Search for "Rechargeable HP Calculator Battery Classic CASE"), but instead adapts a common (i.e. cheap) lithium-ion camera battery. I chose a camera battery as these are well supported by stand alone chargers.

[mfleming]

Sounds like a great idea, but what is the capacity of the Lion battery? Compared to say three AA (not aaa) 1900 mAh (min) Eneloops?

[Artur - Brasil]

(01-08-2020 04:06 AM)Craig Bladow Wrote:  That's awesome! How did you connect the battery to the calculator's power terminals?

Well, I Just soldered two wires to conectors.
As bl50a is a small battery, I put two of them um paralelo, also soldered one to another.
Not The Best solution, but I will Not return to Ni-MH batteries any more. They get too Hot and leak.
I believe these small cell batteries are 950mAh each.

The adaptation to 67 was easier than 41, as it didn't need The step-UP converter (4v tô 6v).
For The printer and cassete, I used bigger batteries and no step-UP to, if I remember well.

[Craig Bladow]

(01-08-2020 05:47 AM)mfleming Wrote:  Sounds like a great idea, but what is the capacity of the Lion battery? Compared to say three AA (not aaa) 1900 mAh (min) Eneloops?

The batteries I have on hand are 1350 mAh. How would you charge the eneloops?

[Artur - Brasil]

(01-08-2020 04:29 AM)Craig Bladow Wrote:  Now we need some one made a battery case, similar to the case that holds 3 AAAs, made for the classic calculators and available on TAS (Search for "Rechargeable HP Calculator Battery Classic CASE"), but instead adapts a common (i.e. cheap) lithium-ion camera battery. I choose a camera battery as these are well supported by stand alone chargers.

I saw the item on auction. You will have to remove springs and cut the internal walls.
As the batteries compartment in 67 is large (3 AA bateries), I belive a small plastic rectangular box that could fit in it, leaving space for charger.
Also, consider what I said: once you put LI-Ion in one HP calculator, you will replace in all, as NI-MH are a risk to them and will never remove them again or for a long time...
So, some wires are one acceptable solution. Or small cooper sheets soldered to batteries and going down to make contact with calculator.
Best regards,
Artur

[Artur - Brasil]

Eneloops?
Li-Ion charge module like TP4056, the ones with OUT and BAT terminals inline are very cheap, they are small, very cheap and can charge small or even large batteries easily. They feet on back off battery compartment door, as I did.
The rest of space are free for battery. As I used two Bl-5F (950mAh each) in paralell, i believe I got 1900mAh.
What is the battery you are talking about? Put a link and I'll get a better idea about what you think.

Artur

(01-08-2020 05:28 PM)Craig Bladow Wrote:  

(01-08-2020 05:47 AM)mfleming Wrote:  Sounds like a great idea, but what is the capacity of the Lion battery? Compared to say three AA (not aaa) 1900 mAh (min) Eneloops?

The batteries I have on hand are 1350 mAh. How would you charge the eneloops?

[Dave Britten]

(01-08-2020 05:42 PM)Artur - Brasil Wrote:  Eneloops?
Li-Ion charge module like TP4056, the ones with OUT and BAT terminals inline are very cheap, they are small, very cheap and can charge small or even large batteries easily. They feet on back off battery compartment door, as I did.
The rest of space are free for battery. As I used two Bl-5F (950mAh each) in paralell, i believe I got 1900mAh.
What is the battery you are talking about? Put a link and I'll get a better idea about what you think.

Artur

Eneloop is a popular brand of NiMH rechargeable batteries. I use the AAAs in my HP 65.

[Craig Bladow]

Here is an article on building classic battery packs I found a link to in the articles section of the forum: http://homepage.divms.uiowa.edu/~jones/hp/battery/

My thought is to build an adapter that would fit a particular camera battery that can be easily removed and charged externally. For example the third party batteries sold as substitutes for the Olympus Li-90/92b batteries. On Amazon there are several options for less than $20 that include two batteries.

What is needed then are spring loaded contacts, a case (3d printed most likely), and thin conductive material to connect to the calculator's contacts. This material needs to be compatible with the metal (what is it?) used for the contacts so it does not cause corrosion.

[Artur - Brasil]

I got the message!
Well, my aproach is completely different of what you say.
No more Ni-MH batteries neither NiCd. They are difficulto to control the charge process, as you have to monitor the temperature and voltage on cells.
HP charges are just one transformer inside - completely no control - circuits in calculators are so simple that some times you see just a resistor to limit current.
I had one cassette reader destroyed because one cell was defective and the whole set got so hot that case of drive was bended by heat.
Also, the leakage is a painfull and destroy everything in his way.

No, no! Li-Ion batteries have much, but 1000% better charging control, and in very thinny reay-to-use boards, that are sold for a banana cost. Your calculator got discharged, get one cell phone charger and plug it in. Couldn't be more easy!

Don't use any more NiCD or NiMH batteries. Adapt all your calculators to Li-Ion batteries. They are lighter, less expensive, easier to charge and last more.

My sincere advice!
Artur

(01-08-2020 06:09 PM)Dave Britten Wrote:  

(01-08-2020 05:42 PM)Artur - Brasil Wrote:  Eneloops?
Li-Ion charge module like TP4056, the ones with OUT and BAT terminals inline are very cheap, they are small, very cheap and can charge small or even large batteries easily. They feet on back off battery compartment door, as I did.
The rest of space are free for battery. As I used two Bl-5F (950mAh each) in paralell, i believe I got 1900mAh.
What is the battery you are talking about? Put a link and I'll get a better idea about what you think.

Artur

Eneloop is a popular brand of NiMH rechargeable batteries. I use the AAAs in my HP 65.

[Dave Britten]

(01-08-2020 08:05 PM)Artur - Brasil Wrote:  I got the message!
Well, my aproach is completely different of what you say.
No more Ni-MH batteries neither NiCd. They are difficulto to control the charge process, as you have to monitor the temperature and voltage on cells.
HP charges are just one transformer inside - completely no control - circuits in calculators are so simple that some times you see just a resistor to limit current.
I had one cassette reader destroyed because one cell was defective and the whole set got so hot that case of drive was bended by heat.
Also, the leakage is a painfull and destroy everything in his way.

No, no! Li-Ion batteries have much, but 1000% better charging control, and in very thinny reay-to-use boards, that are sold for a banana cost. Your calculator got discharged, get one cell phone charger and plug it in. Couldn't be more easy!

Don't use any more NiCD or NiMH batteries. Adapt all your calculators to Li-Ion batteries. They are lighter, less expensive, easier to charge and last more.

My sincere advice!
Artur

Personally, I like sticking with the NiMHs. There are a ton of non-standard Li-Ion battery packs, but NiMH AAAs or AAs are easy to find. I never charge them inside the calculator; I use a modern charger that charges and monitors each cell individually. I'm getting great run time on my 65 with Eneloop AAAs, even with quite a bit of card reader use. Plus lithium batteries tend to be much more of a fire hazard.

The charger I bought can handle a variety of Li-Ion barrel-style cells (rather than the flat-packs used in most phones). I wonder if any of those would be small enough to fit inside the calculator with a holder similar to what's available for AAAs.

[Artur - Brasil]

(01-08-2020 08:18 PM)Dave Britten Wrote:  Personally, I like sticking with the NiMHs. There are a ton of non-standard Li-Ion battery packs, but NiMH AAAs or AAs are easy to find. I never charge them inside the calculator; I use a modern charger that charges and monitors each cell individually. I'm getting great run time on my 65 with Eneloop AAAs, even with quite a bit of card reader use. Plus lithium batteries tend to be much more of a fire hazard.

The charger I bought can handle a variety of Li-Ion barrel-style cells (rather than the flat-packs used in most phones). I wonder if any of those would be small enough to fit inside the calculator with a holder similar to what's available for AAAs.

I do understand you, but see advantages: you won't need an special charger neither remove batteries from calculator (or accessory).
About flat-battery, they are smaller and fit in every place.
Aboubt fire, yes, it's possible, I have to admit.
Well, it's a personal decision at all. But I don't regret about replacing Ni_MH or NI-Cd for Li-Ion.
I also saw At TAS (why this?) in Usa there are tons ofnoptions for chargers, chargers with bat holders!, charging indicators, many, many, many.
If I Live there, my restaurations Would bê At another step!!
(my cell is changing every Word I type in... I really hate my cell)
Now, I'll fix the card reader!
Cheers!
Artur

[Dave Britten]

(01-08-2020 09:44 PM)Artur - Brasil Wrote:  

(01-08-2020 08:18 PM)Dave Britten Wrote:  Personally, I like sticking with the NiMHs. There are a ton of non-standard Li-Ion battery packs, but NiMH AAAs or AAs are easy to find. I never charge them inside the calculator; I use a modern charger that charges and monitors each cell individually. I'm getting great run time on my 65 with Eneloop AAAs, even with quite a bit of card reader use. Plus lithium batteries tend to be much more of a fire hazard.

The charger I bought can handle a variety of Li-Ion barrel-style cells (rather than the flat-packs used in most phones). I wonder if any of those would be small enough to fit inside the calculator with a holder similar to what's available for AAAs.

I do understand you, but see advantages: you won't need an special charger neither remove batteries from calculator (or accessory).
About flat-battery, they are smaller and fit in every place.
Aboubt fire, yes, it's possible, I have to admit.
Well, it's a personal decision at all. But I don't regret about replacing Ni_MH or NI-Cd for Li-Ion.

Now, I'll fix the card reader!
Cheers!
Artur

Yup, it's pretty cool, so don't let me stop you.

[teenix]

I've been using these to power the CPU boards while in development. They are pretty cheap on TAS and the batteries fit in the calculator compartment. Just plug into the USB port to charge. They would need something made to mate with the battery terminals though.

cheers

Tony

[mfleming]

(01-08-2020 05:42 PM)Artur - Brasil Wrote:  Eneloops?
Li-Ion charge module like TP4056, the ones with OUT and BAT terminals inline are very cheap, they are small, very cheap and can charge small or even large batteries easily. They feet on back off battery compartment door, as I did.
The rest of space are free for battery. As I used two Bl-5F (950mAh each) in paralell, i believe I got 1900mAh.
What is the battery you are talking about? Put a link and I'll get a better idea about what you think.

Artur

(01-08-2020 05:28 PM)Craig Bladow Wrote:  The batteries I have on hand are 1350 mAh. How would you charge the eneloops?

Here are a couple of pictures of a rebuilt Classic battery pack using Eneloop rechargable NiMH batteries. The batteries and associated metal bits are such a tight fit in the bottom half of the case that the top half presses into place very firmly.

       

I use a bit of copper sheet for the bar bridging a pair of batteries (+ to -) with notches as marked to fit the ridges in the case. The external contacts themselves can sometimes be salvaged from the battery pack if corrosion is not too bad, or they can be formed from 1/4" brass angle brackets using the original contacts as templates.

I generally mark painters tape applied to each end of the battery pack with the battery polarity, or I use tape inside the pack to mark the orientation of each battery. Flat-top batteries would make an easier fit into the case but then you'd need to seal the case with tape. A friction fit with the above arrangement holds *very* tightly, but can be prised open so that the batteries can be removed and charged in a regular charger.

Although it works great for me, naturally Your Mileage May Vary!
~Mark

[Artur - Brasil]

Hi,

I apreciated very much the replies to my post and I believe all aproaches are good, as they preserve this part of computing history working!

But now I need some information about HP-67. Yesterday I openned my unit again to fix the card reader. Some wires just twisted on terminals, broken soldering and so on. Well, I fixed everything. The card reader is now giving sinals it is alive - not working properly yet.

But another more serious problem arose: the keyboard!
HP-67 can be completely dismantled and give access to all parts of keyboard, which is completely different of HP-11C, 15C, 41C, in which keyboard plate is melted on chassis.

Weel, hp-67 has some rectangular plates for contact, and covering it a very simple sheet of of very simple plastic. Is this correct?
HP-15C has an adhesive plastic, not an usual plastic, covering the plates (disc format), and one thiny sheet of rubber.

After closing my 67, the keys got loose. I tried other solutions, but none worked. Around 4hours trying and nothing.

Just behind HP-67 keys, there is a hole. There should be something between them and contacts?

Many thanks for your support!

Artur

[teenix]

(01-09-2020 11:40 AM)Artur - Brasil Wrote:  Hi,

I apreciated very much the replies to my post and I believe all aproaches are good, as they preserve this part of computing history working!

But now I need some information about HP-67. Yesterday I openned my unit again to fix the card reader. Some wires just twisted on terminals, broken soldering and so on. Well, I fixed everything. The card reader is now giving sinals it is alive - not working properly yet.

But another more serious problem arose: the keyboard!
HP-67 can be completely dismantled and give access to all parts of keyboard, which is completely different of HP-11C, 15C, 41C, in which keyboard plate is melted on chassis.

Weel, hp-67 has some rectangular plates for contact, and covering it a very simple sheet of of very simple plastic. Is this correct?
HP-15C has an adhesive plastic, not an usual plastic, covering the plates (disc format), and one thiny sheet of rubber.

After closing my 67, the keys got loose. I tried other solutions, but none worked. Around 4hours trying and nothing.

Just behind HP-67 keys, there is a hole. There should be something between them and contacts?

Many thanks for your support!

Artur

There are locating holes for the key circuit board that mate with the black plastic support. (This is the large part that houses the card reader) These two parts should sit flat against each other. Sometimes they are not lined up properly on reassembly and there can be a larger than normal space between the back of the keys and the key contacts. These two parts are best mated together before placing back in the calculator case.

You will know if the assembly is sitting properly in the case as there will be no movement if you push on any of the corners. If the black plastic rocks when you push, then it is not seated properly.

Also, be careful not to move the board around too much when it is disassembled or you risk breaking one or both of the power wires on the top corner of the circuit board. The other problem that can occur is that one or both of the brass switch connectors can fall out of the back of the switches and float around the circuit board causing shorts. This can damage the circuit.

Yes, just a simple plastic covering. It should also have 2 small holes that mate with small protrusions on the keys retainer.

cheers

Tony