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Company typeCAD Board Name typeCAD 1Hz Variant Sheet 1 of 1
Filename ./build/one_hz.kicad_pcb Revision Date 2025-07-20

1Hz

Stackup Dimensions Drills
{Stackup}
{Edge.Cuts,User.1,F.Fab}
{Drill}

Top

{F.Cu}

Bottom

{B.Cu}
flipped

Renders

Top View Bottom View
{Render/front/90/0/0}
{Render/bottom/0/0/360}

Top Assembly

Top View Render
{Edge.Cuts,F.Cu,F.Mask,F.Fab}
Front render

Bottom Assembly

Bottom View Render
{B.Cu,B.Mask,B.Fab}
Bottom render

Test Points

The circuit includes four test points for verification and debugging:

Test Point Signal Frequency Purpose Location
TP1 TCXO Output 4.194304 MHz Verify oscillator operation U1 Pin 3
TP2 First Division 256 Hz Verify 74HC4060 operation U2 Pin 3 (Q14)
TP3 Final Division 1 Hz (unbuffered) Verify 74HC4040 operation U3 Pin 1 (Q8)
TP4 Buffered Output 1 Hz (buffered) Verify 74HC244 operation U4 Pin 8

Bill of Materials

Reference Component Value/Part Number Package Description Estimated Cost
U1 TCXO SIT8008BI-82-30E-4.194304 SMD 5.0x3.2mm 4.194304 MHz TCXO, ±25ppm, 3V $15.00
U2 Binary Counter 74HC4060N DIP-16 14-stage binary counter with oscillator $1.50
U3 Binary Counter 74HC4040N DIP-16 12-stage binary counter $1.25
U4 Buffer/Driver 74HC244N DIP-20 Octal buffer/line driver $1.75
C1 Capacitor 100nF 0603 TCXO decoupling capacitor $0.05
C2 Capacitor 100nF 0603 74HC4060 decoupling capacitor $0.05
C3 Capacitor 100nF 0603 74HC4040 decoupling capacitor $0.05
C4 Capacitor 100nF 0603 74HC244 decoupling capacitor $0.05
C5 Capacitor 10µF 0603 3V rail bulk filtering $0.15
C6 Capacitor 10µF 0603 5V rail bulk filtering $0.15
R1 Resistor 10kΩ 0603 74HC4060 reset pull-down $0.02

Mathematical Calculations

TCXO → 74HC4060

4,194,304Hz16,384=256Hz

74HC4060 → 74HC4040

256Hz256=1Hz

Output Accuracy

±25ppm×86,400seconds/day=±2.16seconds per day

Signal Path

uml diagram