Huyser bookstore in Delft ran a competition to promote the book from Arne and Carlos "55 Christmas Balls to Knit", see the promotional video here. Just before the deadline (1.11.11) our son Daniel was born, but we managed to find time to finish the Ball and submit it.
Naturally Ana chose a pattern and knitted the ball, I took care of the electronics. We were so late entering the competition that we only have "night shots" before submitting the ball...
It is a simple ATTiny15L powered with 3x AAA alkaline batteries.
There are 4 LEDs connected to the ATTiny, each in one of the reindeer's nose.
I've made a 32bit pseudo random number generator with a LFSR. The ball to lit is randomly picked (1..4) and also the fade-in time (1-2sec), fade-out time (1-2 sec) and off-time (2..4 x 2.5sec i.e. number of watchdog cycles).
The average measured power consumption is 1.5mA so one can expect about 1000 hours of operation from 3 standard cells.
(click on the circuit for a better view)
The schematic is not exactly this one, this is for another project that hopefully will come out before Christmas, just remove the solar charger, the voltage measuring and that's it!
We got the third prize, 100EUR in books!!!
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