Creating overlays / custom key kaps for cherry switches

[Harald]

(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.