[Swansea Hackspace] Daily Countdown (but working days not calendar)

[Justin Mitchell]

On Thu, 2016-01-28 at 11:08 +0000, Nathan Hackett wrote:
> From memory I got about 18 hours from 3 AA batteries, with 3x 2.3inch
> high led digits. That was at max brightness though, could get a lot
> more running them dimmer. Or pick up some £10 10000mah phone charger
> packs, that would help. The other downside of larger displays is they
> can have several leds in series per segment, which results in a higher
> voltage-drop than the arduino can cope with on its own. Things get
> complicated. LCD might indeed be more suitable. :)

A chip like the MAX7219 will drive upto 8x 7-segment digits, do alot of
the hard work for you, and present a simple SPI interface to the
arduino/RPi

http://playground.arduino.cc/Main/MAX72XXHardware

https://www.maximintegrated.com/en/products/power/display-power-control/MAX7219.html

Also, how BIG did you envisage this display being ?