[time-nuts] Solstice Puzzle

[Mike S]

At 01:04 AM 12/17/2011, Neville Michie wrote...
>This clock consists of 6 cubes, each has a digit display on one face.
>It does not matter how you arrange them, if they are in a line they
>will display the right time. (there may also be a nearby box 
>containing a Rb or GPS time standard.)

Wow. Looks like nobody takes time to read anymore. All the responses so 
far act as if the line "each has a digit display on one face" wasn't 
even there, and assume the boxes have to figure which side is up and 
which side to use as a display.

They just need to figure out where they are in sequence. I'd use a 
microcontroller in each, to drive the display, and also to monitor an 
IR sensor and drive an IR LED. Sensor on the right of each box (as you 
face the arrangement of boxes), LED on the left. Box on the right 
(seconds - ones digit) receives no input from the sensor, knows it's 
the rightmost box. It's also the one that keeps time. Displays last 
digit, passes 5 remaining digits out the IR LED to the next box. Each 
box strips the last digit, displays it, sends the remaining ones on. 
Repeat. Last box receives one digit, displays it, done. Every time the 
seconds increment, the rightmost box passes the new time along.

Obviously, if you're thinking of some type of electrical connection 
between them, it's the same, only different.

The rest is just details, like how to modulate the signal, receive time 
from your standard, etc. If you want the digit changes closely sync'd, 
figure out the delay through each box, and each one delays the display 
by the delay time*number of digits it's passing on (and the first one 
starts the update sooner to accomodate).