2 layers178 × 711 mm
4 layers281 × 142 mm
Turing Machine
MelonMars/TuringPCBA Turing Machine that does not use any premade microchips, but rather is built exclusively on simple components.
- Size
- 281 × 142 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 255
- Nets
- 212
- Pads
- 827
- Tracks, vias
- 2,266, 447
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 11 May 2026
- Updated
- 24 Jun 2026
Overview
Turing Machine is an open-source printed circuit board by MelonMars, from the MelonMars/TuringPCB repository on GitHub. It is a 4-layer board of 281 × 142 mm with 255 parts on 212 nets, routed with 2,266 tracks and 447 vias.
It is built around the 74AHC1G00GW, 74AHC1G04SE and 74AHC1G32GW, with the 74HC74D, 74HC138 and 74HC151D among its other parts. Its parts include 193 connectors, 49 ICs, 10 resistors, 1 diode and 1 switch.
Main components
8
74AHC1G00GW
SOT-353-40℃~+125℃ 1.9V、2.9V、4.4V 100mV、550mV 1uA 2 2 2.1V、3.85V 2V~5.5V 5.2ns@5V,50pF 500mV、900mV、1.65V 74AHC 8mA 8mA NAND Gate SOT-353 Logic Gates ROHSTECH PUBLICLogic Gates74AHC1G04SE
SOT-353-40℃~+125℃ 1 1 1.5V~3.85V 1.9V、2.9V、4.4V 1uA 2V~5.5V 500mV~1.65V 7.5ns@5V,50pF 74AHC 8mA 8mA Noise suppression function Schmitt trigger SOT-353 Inverters ROHSDiodes IncorporatedInverters74AHC1G32GW
SOT-353-40℃~+125℃ 1 1.5V~3.85V 1.9V、2.9V、3.94V、4.4V 100mV、100mV、100mV、550mV 1uA 2 2V~5.5V 500mV~1.65V 7.5ns@5V,50pF 74AHC Series 8mA 8mA OR Gate Overvoltage-tolerant input SOT-353 Logic Gates ROHSNexperiaLogic Gates
74HC74D
SOIC-14-40℃~+125℃ 1 15ns 2 2V~6V 3.5pF 37ns@6V,50pF 3ns、3ns、3ns 40uA 5.2mA 5.2mA 74HC Series 82MHz Asynchronous Complementary D-Type Rising Edge Set and Reset SOIC-14 Flip Flops ROHSNexperiaFlip Flops
74HC138
SOP-160℃~+70℃ 24ns@5.0V,16pF 2V~6V 3/8 5.2mA 5.2mA 5uA 74HC Decoder Reverse function Single Supply SOP-16 Signal Switches, Multiplexers, Decoders ROHSGRSignal Switches, Multiplexers, Decoders74HC151D
SOIC-16-40℃~+125℃ 15ns@5V,15pF 2V~6V 40uA 5.2mA 5.2mA 74HC 8/1 Multiplexer Single Supply SOIC-16 Signal Switches, Multiplexers, Decoders ROHSToshibaSignal Switches / Encoders & Decoders / Multiplexers
74HC157D
SO-16-40℃~+125℃ 10ns@6.0V,50pF 160uA 2V~6V 5.2mA 5.2mA 74HC 8/4 Multiplexer Single Supply SOIC-16 Signal Switches, Multiplexers, Decoders ROHSNexperiaSignal Switches / Encoders & Decoders / Multiplexers74HCT193D
SO-16-40℃~+125℃ 23ns 4 4.5V~5.5V 41MHz Asynchronous Binary Counter Rising Edge Synchronous Up Counter、Down Counter SO-16 Counters, Dividers ROHSNexperiaCounters, Dividers
README
README.mdTuring PCB
This is a PCB for a Turing Machine that is made primarily using "simple" components, without using complex microchips or programmable stuff (as that would be cheating). It is designed to be programmed through the transition table being bridged by diodes (e.g. LEDs) in order to represent what is being done and how the machine should progress. It has both an automatic clock and the ability to step through it, to enable debugging programs or just run through them. It has 4 state bits and 8 tape bits. It ended up being much more complex than I thought at first, and took way longer than expected, but it was really enjoyable. It has 6 layers & 2 flood fills for both GND and VCC.
I made this project primarily for the fun of it. I've always found challenges with confounding variables fun and interesting, and believe that this is just sort of the next step in that regard, with Turing Machine's being fun proofs of concept and this being a very restricted form of it.
Bill of materials:
1x PCB (JLCPCB) -- $62.70
Parts
255| Qty | Value | Footprint | References |
|---|---|---|---|
| 192 | Conn_01x02_Socket | Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical | J1, J10, J11, J100, J101, J102, J103, J104, J105, J106, J107, J108, J109, J110, J111, J112 +176 |
| 18 | 74AHC1G00 | Package_TO_SOT_SMD:SOT-23-5 | U14, U15, U17, U20, U22, U23, U26, U27, U30, U31, U34, U35, U38, U39, U42, U43 +2 |
| 8 | 10k | Resistor_SMD:R_0603_1608Metric | R1, R2, R3, R4, R5, R6, R7, R8 |
| 8 | 74AHC1G04 | Package_TO_SOT_SMD:SOT-23-5 | U19, U21, U25, U29, U33, U37, U41, U45 |
| 8 | 74AHC1G32 | Package_TO_SOT_SMD:SOT-23-5 | U18, U24, U28, U32, U36, U40, U44, U48 |
| 7 | 74HC74 | Package_SO:SOIC-14_3.9x8.7mm_P1.27mm | U1, U2, U3, U7, U12, U13, U16 |
| 5 | 74HC138 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U5, U8, U9, U10, U11 |
| 2 | 5.1k | Resistor_SMD:R_0603_1608Metric | R9, R10 |
| 1 | 1N5817 | Diode_THT:D_DO-41_SOD81_P10.16mm_Horizontal | D1 |
| 1 | 74HC151 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U6 |
| 1 | 74HC157 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U49 |
| 1 | 74HCT193 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U4 |
| 1 | Polyfuse | Fuse:Fuse_1812_4532Metric | F1 |
| 1 | SW_Push_SPDT | Button_Switch_SMD:Nidec_Copal_CAS-120A | SW1 |
| 1 | USB_C_Receptacle_USB2.0_14P | Connector_USB:USB_C_Receptacle_GCT_USB4085 | J193 |
Questions
How big is the Turing Machine PCB?
It measures 281 × 142 mm and has 4 copper layers, 1.6 mm thick.
What parts does the Turing Machine use?
255 parts, built around the 74AHC1G00GW, 74AHC1G04SE, 74AHC1G32GW and 74HC74D. 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 Turing Machine KiCad files?
From the MelonMars/TuringPCB repository on GitHub, at the commit this page was made from: the board is Turing Machine.kicad_pcb and its schematic Turing Machine.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Turing Machine design in my own project?
Its repository states no licence, so its author keeps all rights: ask MelonMars before reusing the design.
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