How can I build a small digital counter powered by solar panel?
1. No bigger than 2" x 1.5" x 1"
2. Powered by small solar cell (like those calculators we had in elementary school).
3. Has 4 buttons that adjust the counter; +1, -1, +5, -5.
The solar powered part would be neat, but not a must have. The goal of this device is to be used as a counter for gaming applications d&d hp counter and the like. The dimensions are small because ideally I would be able to place these on a card, character sheet, grid representing a map to track both the number on the counter and the location of the counter. If it is reasonable I would like to have a much smaller device than my original goal of 2" x 1.5" x 1". I have a bit of experience wiring small project on a breadboard and I'm confident I could throw something small together from schematics. The last thing is that I would like to make a number of these, so cheap is good. What I don't know is:
1. Where can I find such a small solar panel?
2. Where can I find such a small digital display counter (2 digits minimum, probably don't need more than 3 digits)?
3. Is there open source software I can use to model a simple circuit and test my schematics before trying to build it?
4. Tips for creating a small circuit board in the event one is required.
This is not a hobby area I have explored much so I may not be using the proper terms and this project may not be feasible so please forgive me if you find this to be a silly request.
Thank you for your time.