About the article

Tri-State Time

Quartz clock with a trinary display

Tri-State Time

Inspired by a binary clock he saw at a mathematics museum the author of this design went one step further and came up with a more mathematically challenging timepiece...

This unusual large format digital clock in the photo shows the time in binary and is exhibited at the German Museum of Mathematics ‘Mathematikum’ in the town of Giessen, Germany. The museum is the brainchild of Prof. Beutelsbacher and has been described as the fi rst ‘hands-on’ mathematical museum in the world.

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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.

Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Component list


R1-R8 = 220 ?

R9-R26 = 1k?8

R27-R37 = 100k?

R38 = 4M?7

R39 = 270k?


C1 = 27pF

C2 = 100pF

C3 = 100?F 25V radial

C4-C15 = 100nF


D1-D8 = bicolour LED, red/green, common cathode (e.g. Conrad Electronics 185000)

D9- D22 = 1N4148

T1-T18 = BC547B

IC1-IC9 = 4017

IC10 = 4060

IC11 = 4081

IC12 = 4013


JP1,JP2 = 3-way SIL pinheader with jumper, or miniature changeover switch

X1 = 32.768kHz quartz crystal

7 wire links

PCB, ref. 060030-1 from www.thepcbshop.com

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