||Width of case 75 cm. Height of case 80 cm (excluding tube extending
||Minutes trays room 2, 5 and 6 balls and count to 60. Hours trays room
4 and 6 balls and count to 24.
||Standard ping pong balls. 24 balls are needed (1 + 4 + 6 + 3 + 5 +
5 extra in fan module)
||Old electronics cooling fan. Rated 115 VAC, 0.22 A. More powerful than
PC power supply fans. A 75 W 230 V light bulb in series adapts to 230 V.
||Lego Tecnic, about 1000 standard parts. Vertical tubes are of plexiglass,
40 mm inner diameter. Case is made of aluminum and 3 mm plexiglass.
||The electronics is visible on the same picture as the fan
arrangement. You can see the circuit board which is mounted with all
the components visible. Microchip PIC16C84 microcontroller. Development
tools MPASM assembler from Microchip. Homemade programmer using design
and program made by Jens Dyekjær Madsen. Program size: 80 program
words. Ordinary AC/DC adapter from 230V AC to 5V DC. Electronic opto-coupled
relay interfaces to mains voltage driving fan.
||There is a button which viewers can press when a light emitting diode
is on. Every "one minute time window" there there is a "50 second time
window" in which a button press will start the fan. If no one has pressed
the button within the "50 second time window", the fan starts automatically.
I believe the possibility to affect the clock behaviour makes the clock
more interesting to children (and maybe to adults also).