I'm 80% complete with the board design:
- size 2.5" x 2" x .25" (inches)
- requires 200 -300 mA at 9 - 15 V, 3 pin Molex connector
- 180V at 10 mA generated on the board
- 3x2 multiplexing (2 on at once)
- supports 2 colon sets
Now I'm wondering what I should have for I/O, possible items:
- 2 time/date/option switch inputs
- alarm enable switch
- GPS input
- alarm output (open collector transistor)
- temperature sensor (could be 9700 sensor, cheap and easy to interface)
- ambient light sensor, either on board or off
- any other items?
What kind of connector? Inline 10 pin .100" connector?
Dont over do the clock, for something like this (small as possible board) you do not need any fancy features. Like humidity sensor, that just sounds stupid to me. Even the GPS is little bit excessive imo.
One thing im not sure about is the ratio of the board dimensions (1,25:1) its close to sqare, i think it would be much more efficient to have it rather longer and slimer. So it would be only deep as the tube diameter and it could rest just under (or behind) the tubes without the pcb sticking out at all. You could make very nice slim clocks this way.