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6 digit IN12 60Hz line frequency logic clock
(Schematic / 50Hz Conversion / BOM / Kit labeling )



TI APP Note Clock PWB
6.00" x 3.25" double sided board, solder mask and silk both sides
Item 1 on the BOM, not included in the parts kit

Circuit Board Only
TI APP Note Clock Parts Kit
Items 2-28 on the

Tubeless Clock Kit
7441 HV Driver ICs (x5)
Item 26 on the BOM, included in the parts kit

7441-5 $11.95
APE1F-2M-10-Z (x5)
Item 27 on the BOM, included in the parts kit

APE1F-5 $27.95
IN12A Nixie Tubes (x6)
Item 29 on the
BOM, not included in the parts kit

6 IN12A
Power Plug
5.5mm OD x 2.5mm ID

CUI Inc PP3-002B
Item 31 on the BOM, not included in the parts kit

CP3-1001 $1.45

Nixie Power Supplies
Item 28 on the BOM, included in the parts kit!

Nixie Tube Sockets
72 pcs, Item 30 on the BOM, not included in the parts kit
Description (Schematic / BOM / Breadboard)
This is a simple hard logic Nixie clock based on a data book application schematic from the mid 1970's illustrating the use of Texas Instruments' 74141 BCD-Decimal nixie decoder-driver IC's.  A few modifications from the original design were implemented:
  • A 5V series regulator instead of the original zener shunt circuit for powering the logic.
  • Neon lamp drive for the AM/PM indicators.
  • Zeroing was added to the line frequency prescaler and 1's digit during setting.
  • The high voltage transformer input has also been replaced by a boost supply for the anode 170V supply.
  • An error in the seconds 10's connection between the decoder and display was corrected.
  • All through hole parts except the capacitors which are 1206 ceramic SMT and the power input connector; see the SMT soldering tutorial here.  A right angle through hole power connecter can alternatively be installed on the SMT pads:  .

IN12's have been used in the design but this will work with any nixie display, the cathodes for each tube are marked on the PWB for easy wiring.  Components are also labeled with their values for easy assembly.

Input power is 9VAC @ 500mA, suggested AC output wall adapters and connector...

  • Adapter: CUI EPA090050-S/T-SZ, 120VAC in / 9VAC out @ 500mA (Digikey T1004-ND)
  • Adapter: ReliaPro ACU090050, 120VAC in / 9VAC out @ 500mA (Jameco 100061)
  • Adapter: Radio Shack 15-1963, 120VAC in / 12VAC out @ 400mA (Jameco 2076543)
  • Adapter: Check Marlin P Jones for good deals on adapters, I've seen a 12V 400mA for $0.50!

Any questions or comments?
This page last updated on November 26, 2012