Electronic Hourglass

an unusual PIC project

In a real hourglass, silicon dioxide (SiO2) in the form of extremely fine quartz sand trickles from one bulb into the other. In the electronic version, the only silicon to be found is in a small, oscillating wafer of quartz and a few chips in the PIC microcontroller and transistors. And instead of grains of sand, points of light trickle downwards…Of course, the points of light in the electronic hourglass do not have any direct relationship to the silicon in a conventional hourglass, since there is no silicon among the various elements (primarily gallium and arsenic) in the chips of the LEDs used here. Aside from that, you might wonder why anyone would want to build an electronic hourglass.

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Materials

020036-PCB.pdf

020036-11.zip

Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.

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PCB

Download Gerber file: 020036-1.zip

Component list

Resistors:
R1 = 4-way 10k? SIL array
R2, R4, R7-R15, R24-R31 =10k?
R3 = 680?
R5 = 270?
R6 = 4k?7
R16-R23, R32-R39 = 100k?
Capacitors:
C1,C8 = 10µF 25V radial
C2-C5 = 100nF
C6,C7 = 22pF
Semiconductors:
D1-D65 = LED, 5mm, red, lowcurrent
D66 = 1N4001
T1-T16 = BC557
T17 = BC547
IC1 = PIC16F84-04/P, programmed, order code 020036-41
IC2, IC3 = 74HCT138
IC4 = 78L05
Miscellaneous:
X1 = 4MHz quartz crystal
S1 = miniature hex encoder switch, 16 positions (Hartmann type PT65 303, from Conrad Electronics, # 705497)
S2,S3 = single contact switch, make contact, e.g., type D6
Ls1 = miniature loudspeaker, 8? 0.1W
JP1 = jumper
PCB, order code 020036-1
Disk, project software, order code 020036-11 or Free Download