2 layers245.1 × 160 mm
8-Bit CPU 32k
slu4coder/Minimal-64x4-Home-Computer
My DIY TTL home computer with VGA and PS/2 and 4x the processing power of a Commodore C64 or Apple II.
139 parts326
2 layers155 × 35 mm
Ruler
wirenux/PCB-RulerA functional 15cm ruler featuring an embedded 4-bit binary counter and a multi-gate logic circuit. Designed in KiCad.
- Size
- 155 × 35 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 48
- Nets
- 42
- Pads
- 166
- Tracks, vias
- 344, 48
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 25 Jul 2026
- Updated
- 25 Jul 2026
Overview
Ruler is an open-source printed circuit board by wirenux, from the wirenux/PCB-Ruler repository on GitHub, published under the MIT licence. It is a 2-layer board of 155 × 35 mm with 48 parts on 42 nets, routed with 344 tracks and 48 vias.
It is built around the 74HC00D, 74HC08D and 74HC193D, with the 74HC86D among its other parts. Its parts include 11 resistors, 8 switches, 7 diodes, 6 capacitors and 5 ICs.
Main components
4
74HC00D
SOP-14-40℃~+125℃ 1.5V、3.15V、4.2V 1.9V、3.7V、5.9V 100mV、400mV、400mV 2 2V~6V 4 40uA 5.2mA 5.2mA 500mV~1.8V 74HC Series 7ns@6V,50pF NAND Gate SOIC-14 Logic Gates ROHSNexperiaLogic Gates74HC08D
SOP-14-40℃~+125℃ 1.5V~4.2V 1.9V、3.7V、5.2V 100mV、400mV 2 27ns@4.5V,50pF 2V~6V 2uA 4 5.2mA 5.2mA 500mV~1.8V 74HC Series AND Gate SOIC-14 Logic Gates ROHSNexperiaLogic Gates
74HC193D
SO-16-40℃~+125℃ 1 18ns@6V 2V~6V 4 49MHz 500mW 74HC Asynchronous Divide-by-2 Reset function、Synchronous counting、Asynchronous parallel load、Multi-mode counting Rising Edge Synchronous Up Counter、Down Counter SO-16 Counters, Dividers ROHSNexperiaCounters / Dividers74HC86D
SO-14-40℃~+125℃ 1.5V~4.2V 20ns@6V,50pF 2V~6V 2uA 4 5.2mA 5.2mA 500mV~1.8V 74HC Series XOR Gate SOIC-14 Logic Gates ROHSNexperiaLogic Gates
README
README.mdPCB Ruler
A functional 15cm ruler featuring an embedded 4-bit binary counter and a multi-gate logic circuit. Designed in KiCad.
Features
- 4-Bit Binary Counter (
74HC193): Tracks and displays counting states across 4 green LEDs. - 5-Gate Logic Demonstrator (
74HC00,74HC08D,74HC86):- AND (
74HC08D) - NAND (
74HC00) - OR (
74HC00configured via multi-gate assembly) - NOR (
74HC00inverters +74HC08DAND gate using De Morgan's Law) - XOR (
74HC86)
- AND (
- DIP Switch Selection: Easily toggle between logic outputs safely mapped to a common output bus with a current-limiting resistor and indicator LED.
- Precision Silkscreen Ruler: Features millimeter and centimeter tick marks.
Gallery
3D Renders
| Front View | Back View |
|---|---|
 |  |
PCB Layout
| Front Copper & Silkscreen | Back Copper |
|---|---|
 |  |
Schematic Diagram
(Downloadable PDF version available in assets/schematic.pdf)
License
This project is release under the MIT License
Parts
48| Qty | Value | Footprint | References |
|---|---|---|---|
| 10 | LOGO | LOGO | G***, G***, G***, G***, G***, G***, G***, G***, G***, G*** |
| 7 | 300Ω | PCM_JLCPCB:R_0805 | R1, R2, R3, R4, R5, R6, R7 |
| 6 | 100nF | PCM_JLCPCB:C_0805 | C1, C2, C3, C4, C5, C6 |
| 4 | 10kΩ | PCM_JLCPCB:R_0805 | R8, R9, R10, R11 |
| 4 | Green | PCM_JLCPCB:D_0805 | D1, D2, D3, D4 |
| 2 | Yellow | PCM_JLCPCB:D_0805 | D5, D6 |
| 1 | 74HC00 | Package_SO:SSOP-16_5.3x6.2mm_P0.65mm | U5 |
| 1 | 74HC00 | Package_DIP:DIP-14_W7.62mm | U2 |
| 1 | 74HC08D | PCM_JLCPCB:SOIC-14_L8.7-W3.9-P1.27-LS6.0-BL | U4 |
| 1 | 74HC193 | Package_DIP:DIP-16_W7.62mm | U1 |
| 1 | 74HC86 | Package_DIP:DIP-14_W7.62mm | U3 |
| 1 | A | Button_Switch_SMD:SW_Push_1P1T_XKB_TS-1187A | SW7 |
| 1 | B | Button_Switch_SMD:SW_Push_1P1T_XKB_TS-1187A | SW8 |
| 1 | Battery_Cell | Battery:BatteryHolder_Multicomp_BC-2001_1x2032 | BT1 |
| 1 | Binary | Button_Switch_SMD:SW_SPDT_CK_JS102011SAQN | SW2 |
| 1 | Gate | Button_Switch_SMD:SW_SPDT_CK_JS102011SAQN | SW3 |
| 1 | Minus | Button_Switch_SMD:SW_Push_1P1T_XKB_TS-1187A | SW6 |
| 1 | Plus | Button_Switch_SMD:SW_Push_1P1T_XKB_TS-1187A | SW5 |
| 1 | Power | Button_Switch_SMD:SW_SPDT_CK_JS102011SAQN | SW1 |
| 1 | Red | PCM_JLCPCB:D_0805 | D7 |
| 1 | SW_DIP_x05_Gate | Button_Switch_SMD:SW_DIP_SPSTx05_Slide_6.7x14.26mm_W6.73mm_P2.54mm_LowProfile_JPin | SW9 |
Questions
How big is the Ruler PCB?
It measures 155 × 35 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Ruler use?
48 parts, built around the 74HC00D, 74HC08D, 74HC193D and 74HC86D. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Ruler KiCad files?
From the wirenux/PCB-Ruler repository on GitHub, at the commit this page was made from: the board is Ruler.kicad_pcb and its schematic Ruler.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Ruler design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
Similar boards
- 2 layers191.8 × 121.3 mm
8-Bit CPU 32k
slu4coder/Minimal-UART-Computer-1-2
Legacy: Version 1 and 2 of my TTL-only CPU featuring UART I/O, an expansion port, 512KB SSD at up to 10MHz clock speed
109 parts184 - 2 layers306.1 × 130.2 mm
8-Bit CPU 32k
slu4coder/Minimal-64-Home-Computer
Legacy: Full TTL-only home computer with VGA and PS/2 and twice the processing power of a Commodore 64
132 parts94 - 2 layers178 × 711 mm
- 2 layers213.1 × 129 mm
- 2 layers180.3 × 112.4 mm
- 2 layers369.6 × 127.6 mm
- 4 layers100 × 100 mm
