HP-21-25 calculator battery case online

Years ago, I had an HP, but I don't remember the model. It was graphing model though.
I don't know what I would have done with it.
I still have the little TRS 80 pocket computer with the printer. I've been meaning to check it out for value.
In the dollar store the other day, I see a scientific calculator hanging on the rack. A dollar !
I don't really need it, but for a dollar I couldn't pass it up !

I started out with The Craig 4501 in the early 70s. I Had a friend who was really smart. He introduced me to the second calculator that I owned.

That was the HP 25. I didn't understand Algebra let alone Higher Math. I was Working with Him at The Long Beach Naval Shipyard, in Shop 67 which was the Electronics section. He was a new Employee when I met Him. He was the first to introduce me to The RPN system. After I moved up North He got in Contact with me letting me know He was then Working At Fort Lewis. Shortly after that I bought the HP 25 and He explained How to use It.

I Had mine for quite some Time then I don't remember What Happened to It. Years later another Friend mentioned He had one but the battery holder and charger were Lost. So I did a trade with Him For a More Advanced Algebraic Casio that I used in College.

I have tried to find a holder and charger for quite a few years at a reasonable price. That was a bust. Finally this last Month I saw one advertised as a replica. The only thing was it didn't include a battery spring. So that's my next objective to find. Then on to finding the Battery wall Charger. I already have the the External charger/battery holder.

I have a dual power supply to test if the calculator worked, I'm glad that worked!

So persistance will Pay off.
I now have several HP Calculators.  One regret though, I had a HP 41 that I gave to a student thinking that Maybe some day I would get it back. Well it didn't happen. So some day I may get another as It was the first Alpha character type on the market and had a simple Programing system.

I seen a lot of the HP 25s and HP 41s for sale but their way too expensive for my taste, a lot are selling for more than the original selling price.
One thing I found out is to not use alkaline batteries in it, They are Higher voltage that what the calculator was designed for. And they are a little bit longer so they are a very tight fit and hard to insert and remove. My latest Calculator is the HP 48SX. There are a couple of other Calculators I'd like to get, one is the HP Prime and the other is a non HP product called the DM Swissmicros 42

It's really something that there would be enough demand for someone to develop a program for that.
Nice find !
Paul

Heres a company that uses a 3D printer to make battery holders for the Hewlett Packard 21 & 25 Scientific Calculator.
This was very hard to find. Mine was missing so I went on EBay but in this circumstance I didn't find any for sale. Yes there were The calculators themselves, Some at ridiculously high prices.

Name: Shapeways
link to see.



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Click Here!

or this link
HP 21 and HP 25 battery holder.
or both
Also you can download a graphic that you can rotate to get a better view.
You will have to find a spring set for the batteries to work.
I Have not found a double coil spring, there are things you can possibly do that may work.
You can try soldering two of them togather, You could use a number of other types of springs.
[You must be registered and logged in to see this image.]  [You must be registered and logged in to see this image.]This bottom one you could use sideways and solder two of them together. There are also some of the springs that have an extension wire and you could solder those together.
If you con figuration works the springs will help lock the case in place when the batteries are in place.
Let us know what works for you. Most of the parts suppliers like Mouser, Allied, will have them.

Here's a link to a topic on springs.
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