OClock is a simple Arduino project. a clock with 7-segment display an atmega 168/328 and 2 buttons and 6 resistors.
I use this 7-segment display:http://www.robot-italy.com/it/7-segment-display-4-digit-white-single-header.html datasheet:http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Components/LED/ATA3491BW.pdf
1 x atmega-168/328
1 x 7-segment 4 digit
4 x 220omh resistor
2 x 10Komh resistor
2 x pushbutton
2 x 22pF capacitor
1 x 16Mhz crystal
1 x lm7805
1 x 100uF capacitor
1 x 10uF capacitor
1 x any silicon diode
1 x 9-volt battry