HP Forums

(07-07-2017 06:07 AM)Paul Dale Wrote: [ -> ]

(07-06-2017 01:54 PM)Harald Wrote: [ -> ]Close, but not quite. They are VFD tubes, like these:

Beautiful. Do they come in 14-16 segment (or better a 22 segment) version?


Pauli

Yes, there are 16 segment ones:
http://www.tube-tester.com/sites/nixie/d.../IV-17.pdf

But they are much larger, 19mm in diameter instead of the 11mm of the IV-3 I am using.

Are the 19mm tubes feasible? It is much more interesting being able to display letters.
I'd be willing to try some bespoke wooden cases.

I love looking at PCB graphics. They are beyond my ability to design but still interesting to look at.


Pauli

Why the diodes across each switch?
Is there a back-EMF problem?


Pauli

(07-07-2017 08:37 AM)Paul Dale Wrote: [ -> ]Why the diodes across each switch?

Key roll-over. Without the diodes, pressing multiple keys at the same time can lead to ghosting, i.e., erroneous keypresses being registered.

(07-07-2017 08:36 AM)Paul Dale Wrote: [ -> ]Are the 19mm tubes feasible? It is much more interesting being able to display letters.
I'd be willing to try some bespoke wooden cases.

I love looking at PCB graphics. They are beyond my ability to design but still interesting to look at.


Pauli

You'll end up with a calculator that is at least 30cm wide (assuming 15 digits). Other than that they are perfectly feasable.
This project is based on Tonys emulation and therefore uses the PIC. For the 16 segment tubes I'd probably go for a larger controller - but someone would have to write the firmware ;-)

PCB design isn't too difficult - having said that, I have already spotted a couple of minor issues that would need correcting if this is going to be more than a one off.

Regarding the diodes: The switches come with them - but only sometimes, and that is why my design doesn't use the ones integrated into the switch.
In this design diodes are needed to stop the keyboard interfearing with the display. Tony uses the same ports to scan display and keyboard.

PS:
I almost forgot about the wooden case. I was thinking of that, too.
The display and keyboard PCB are supposed to be seperated and connected by a ribbon cable. The idea being that they can be at different angles to allow for comfortable typing and good legibility of the display at the same time.

(07-07-2017 11:02 AM)Harald Wrote: [ -> ]You'll end up with a calculator that is at least 30cm wide (assuming 15 digits). Other than that they are perfectly feasable.

That's more space for keys
The HP 97 is 23cm wide which is a comfortable size. At 30cm, a standard keyboard would fit.

Quote:PCB design isn't too difficult - having said that, I have already spotted a couple of minor issues that would need correcting if this is going to be more than a one off.

I'd say software design isn't difficult I doubt I'd be able to design a PCB well. I'm sure anything I did design would fail emissions testing badly if it did somehow work.


These would go well with a wooden case: https://mechanicalkeyboards.com/shop/ind...tail&p=295 A touch of pyrography for the labels.


Pauli

Not sexy glass tubes, but these might be fun: https://www.youtube.com/watch?v=E2y0MRN4Z5g


Pauli

Harald, are you aware of retro-style keycaps along the lines of what Datamancer (https://datamancer.com/) offers? Their construction should allow custom labels (even coloured ones) quite easily. Maybe it would be a good thing to ask them.

As opposed to all the other custom-label offerings linked to so far, these keys don't wear off because there is some plastic/glass protecting the legends.

If you're looking at keycaps for a calculator...

Will you be using functions, and / or multi-functions? On a standard keycap, the shifted "!" is usually above the " 1 ". If you have more than one function, or you want to use a word, or even an equation like "log x" you may need to use the FRONT of the keycap - and maybe a different color.

Using the front of a keycap means you probably want "DSA" or "G200" format, which tend to have a low profile and a slanted front - increasing visibility of any front text.

If you're designing a one-off set, I'd suggest decals. I'd also suggest white / light gray keycaps, to increase contrast when your CMYK printer ink makes labels on transparent paper. If you insist on white text, home-made decals are going to be a problem. Not impossible, just... tricky.

Finally some progress!

The PCBs were stuck in customs for almost four weeks. They have now arrived and I have to order new ones - the holes for the VFD tubes are to small. But the rest isn't looking too bad:



I have ordered some blank key caps from china and will probably go down the decal route.
The duble shot keys I found are not 50 sets, but 500 sets minimum order quantity, and the printed ones are only single colour print.

(08-14-2017 02:18 PM)Harald Wrote: [ -> ]I have ordered some blank key caps from china and will probably go down the decal route.
The duble shot keys I found are not 50 sets, but 500 sets minimum order quantity, and the printed ones are only single colour print.

If you prefer vinyl overlays, which are much cheaper than double moulded keys, you have to create a .pdf file with the keys and contour layer. Let make you an offer from "Colour Connection" in FFM. 3 DINA4 sheets are about 150,- Euro. The quality of the material and adhesive is very good, the printing was better last year, but still reasonable good.

Bernhard

Would laser etched key tops be workable?
Adding ink or paint would be easy.

What you've done so far looks great.


Pauli

(07-10-2017 04:22 AM)sa-penguin Wrote: [ -> ]If you're looking at keycaps for a calculator...

Will you be using functions, and / or multi-functions? On a standard keycap, the shifted "!" is usually above the " 1 ". If you have more than one function, or you want to use a word, or even an equation like "log x" you may need to use the FRONT of the keycap - and maybe a different color.

Using the front of a keycap means you probably want "DSA" or "G200" format, which tend to have a low profile and a slanted front - increasing visibility of any front text.

If you're designing a one-off set, I'd suggest decals. I'd also suggest white / light gray keycaps, to increase contrast when your CMYK printer ink makes labels on transparent paper. If you insist on white text, home-made decals are going to be a problem. Not impossible, just... tricky.

I quite like the DSA key caps. The blank ones are already installed and I am awaiting a double shot num pad set. I'll have to order some printable decals now.

(08-15-2017 06:59 AM)Paul Dale Wrote: [ -> ]Would laser etched key tops be workable?
Adding ink or paint would be easy.

What you've done so far looks great.


Pauli

That might be a good solution, too. I'll try and find out how much that would cost.

I made a little bit of progress. The new PCBs have arrived and I have populated the first one.
The USB interface does not work yet, but that is probably only a minor issue.

Very nice ! I like the landscape arrangement of keys very much !

I should have also gone for such keys instead of torturing myself with tiny things. They fit such a display very well, I think.

Mine is also not that low power

I triple want one of these now


Pauli

(08-29-2017 08:27 AM)Alejandro Paz(Germany) Wrote: [ -> ]Very nice ! I like the landscape arrangement of keys very much !

I should have also gone for such keys instead of torturing myself with tiny things. They fit such a display very well, I think.

Mine is also not that low power

Yours looks very nice, too, I like the display! Mine was relatively sinple to do as Tony did all the hard work programming the emulator. I admire what you have done with the FPGA!

Edit:
The landscape layout has two advantages in this case:
The calculator width is defined by the display
And with the large keys it is difficult to reach the top keys without touching the bottom ones on a portrait layout.

(08-29-2017 09:07 AM)Paul Dale Wrote: [ -> ]I triple want one of these now


Pauli

I promise you will get one!
I am still pondering if I should provide a kit or not. I am not sure how much demand there would be and how happy people woul be to solder the boards.
If I do a kit it might be worth designing side walls and keyboard supports so the whole thing can be put togather without additional parts.

Thanks

On the key top front, the break point favouring the monochrome keys over the colour ones is thirteen of each key. The $50 setup for monochrome is equivalent to ten colour keys. It might still be possible to find a cheaper source.


Pauli