TriBitLux V2 1

☀️ TriBit Lux

One light. Eight levels. Three bits.
A light-sensing experiment, told through simulations, jumper wires and PCB designs.

3-bit flash ADC concept   ·   LDR input   ·   0–7 display   ·   KiCad + EasyEDA

_{V2.1 · Compact hybrid design · 5 V input / 2.5 V reference · Not yet fabricated}

Latest design · V2.1   /   V2.1 design files   /   Version history   /   Interactive explorer   /   What's next

TriBit Lux converts an LDR's output voltage into one of eight brightness levels and shows the result on a seven-segment display. It began in TinkerCAD, moved onto breadboards, and gradually transferred the encoding and display work from an Arduino to dedicated logic ICs.

This repository presents the latest design first, followed by its earlier versions through the material saved along the way: simulations, sketches, lab photographs, schematics, interactive demonstrations and PCB exports. The breadboard wiring is part of the story—getting it into a compact board was a project in itself.

Where the project stands: V2.1 is now an 80 × 41 mm hybrid THT + SMT design with seven cumulative LEDs, a 2.5 V reference, four mounting holes and a back-side repository QR. The 30 October check reports no PCB errors, unconnected items or schematic-parity issues; 57 existing warnings remain. V2.0 stays as the unfabricated THT milestone, and V2.2 will document the fabricated result.

[blocked]

🧭 Version history · newest first

V2.2 is the planned fabricated result; see what’s next.

[blocked]

✨ V2.1 · Smaller board, clearer feedback

80 × 41 mm · Hybrid THT + SMT · Seven cumulative LEDs · 2.5 V reference

The light-sensing circuit now fits on a compact rectangle with a regular resistor/LED column, two comparator banks, dedicated encoder and decoder ICs, and a buffer for the threshold LEDs. Four mounting holes form a symmetric 73 × 31 mm pattern. The underside carries a threshold guide and a repository QR code.

Front · Read the layout	Back · Follow the levels

JLCPCB is planned to assemble 39 SMT parts per board; XEMACS will solder the 17 through-hole parts. The three-pin header provides 5 V input, ground and the analog sensor voltage for measurement. The nominal thresholds are spaced by 0.3125 V; the displayed level is not calibrated lux.

These are XEMACS’s existing CAD exports. They precede the 30 October silkscreen alignment; updated high-resolution renders will be supplied by XEMACS.

Schematic · V2.1 hybrid circuit

Click the schematic to view XEMACS’s full-resolution export.

The schematic brings together the regulated 2.5 V sensor/reference rail, the LM339 → 74LS148 → 74LS48 display path, and the 74HCT244-driven threshold LEDs. J1 provides 5 V input, ground and the analog sensor-voltage output.

Editable KiCad schematic · Current netlist · Full-resolution schematic image

Design checkpoint · 30 October 2026: PCB DRC reports zero errors, zero unconnected items and zero schematic-parity issues, with 57 existing warnings. Schematic ERC reports zero violations. The board remains unfabricated, and the next manufacturing export needs a fresh supplier DFM check. The older explorer’s V2.1 concept predates this 2.5 V implementation.

Full V2.1 gallery and files · KiCad project · Schematic · SMT BOM · SMT placement · Layout review

[blocked]

🟢 V2.0 · From jumper wires to copper traces

KiCad design · Through-hole components · Unfabricated

V2.0 brings the circuit into KiCad as an editable schematic and PCB. The design includes a 20 mm LDR, a potentiometer for adjusting the response, local decoupling capacitors and a regulated 3.3 V rail for the sensor divider and reference ladder.

The board, four ways

_{Component-populated CAD preview. The LDR and potentiometer have no visible models in this render; both remain in the design and BOM.}

Read the board	Follow the routing
Top · Silkscreen and placement	Layout · Copper and connections

_{Underside of the saved PCB design. All board images here are CAD views, not fabricated hardware.}

Read the silkscreen

The ladder labels identify nominal nodes, not voltage drops across the resistors. Each resistor spans 0.4125 V ideally; the far end of R1 reaches 3.3 V. Circuit references remain in the editable design and parts lists.

The current revision includes revised capacitor footprints, a 15.5 mm lead pitch for the 20 mm LDR, a repository QR graphic, and XEMACS attribution. The custom capacitor and QR footprints are included in the project library.

Schematic · current source export

Click for the PDF, or open the scalable SVG. The older PNG export is retained as an earlier snapshot.

Design checkpoint · 19 October 2026

These results use the project's configured rules. Some footprint/courtyard checks are disabled; this is not a manufacturer DFM approval. See the review and remaining work for the exact limits and open items.

[blocked]

Inside the circuit

                         3.3 V reference ladder
                                  │
Light → LDR + potentiometer → LM339 comparators → Priority encoder → 74LS48 → 0–7
         sensor voltage          parallel decisions     three bits       display

The comparator and logic ICs use 5 V. The sensor divider and reference ladder use the regulated 3.3 V rail. Earlier breadboards used a 74F148; the current V2.0 CAD source specifies a 74LS148.

About the number on the display: it is a relative brightness level, not calibrated lux. The LDR, potentiometer setting and component tolerances influence the physical transition points.

[blocked]

Open the V2.0 design

Open TriBitLux_V2_0.kicad_pro in KiCad to work with the schematic and PCB together. The editable files are the design sources. The JLCPCB CSVs now reflect the current component list and saved placement export. Blank supplier codes require part selection; retained codes are historical selections that still need verification. XEMACS reports that the KiCad export passed all JLCONE checks. Preserve the exact checked archive; regenerate it after any further manufacturing-layer changes. A later PCB save timestamp alone does not establish that the archive is stale.

[blocked]

📟 V1.3 · A window into the sensor voltage

Physical prototype · 16×2 I²C LCD · Parallel monitoring

The Nano gained another role: driving an LCD to make the working flow easier to follow. The hardware seven-segment path remained in place, while the Nano supplied power and sampled the LDR voltage through its own ADC.

LCD-equipped breadboard	Another view of the build

Explore the LCD demonstration

The LCD firmware calculates its own level from the analog voltage; it does not read the encoder bits. That makes the LCD useful for observing the input, while the hardware display follows the comparator and encoder chain. These saved demonstrations belong to the V1.3 archive; the main explorer shows the updated V2.0 logic model.

Open this version: LCD sketch · Original assets

[blocked]

🔢 V1.2 · Hardware takes over the display

Physical prototype · 74LS48 decoder · Serial monitoring

Adding the 74LS48 completed the dedicated hardware display path: comparator bank → encoder → decoder → seven-segment display. The Nano supplied 5 V and received the three encoder bits so the serial console could show them for assurance.

The wiring, up close

Overhead wiring view	Sensor and jumper connections

_{The powered build. The photographed display is driven by the 74LS48.}

Additional powered view	A second captured state

The last two previews link to the original HEIC photographs. Large photographs throughout this page use smaller preview copies; click them for the originals.

Open this version: Serial-monitor sketch · Original photo collection

The saved sketch includes experimental segment-driving code. In the photographed build, the 74LS48 drives the display, while the Nano observes the encoder output.

[blocked]

🧠 V1.1 · Giving the encoder its own IC

Physical prototype · 74F148 priority encoder · EasyEDA design exports

The 74F148 took over priority encoding from the Nano. The comparator bank now fed a dedicated logic IC, which produced the three output bits. The Nano continued to decode those bits and drive the display. This version also has an EasyEDA schematic and PCB design archive.

At the workbench

Schematic beside the build	Full demonstration setup
Schematic and wiring together	Display and reference table

Watching the output	Another angle of the setup
Hardware output alongside monitoring	The complete workbench arrangement

From connections to a board design

Schematic	Routed PCB layout

_{EasyEDA design render with the Nano fitted. This image documents the board design.}

Top board view · SVG	Bottom board view · SVG

Open this version: Schematic PDF · PCB PDF · Arduino sketch · BOM · Gerber archive

[blocked]

🔌 V1.0 · The first breadboard

Physical prototype · Two LM339s · Arduino Nano

The LDR and comparator bank moved out of the simulator and onto a breadboard. The Nano read the comparator outputs and drove the seven-segment display. The saved recording captures the early physical build, with the jumper wiring fully on show.

▶ Watch the breadboard recording · 24 seconds

A closer look at the display pins

Click the animation to explore the display pin layout.

Open this version: Recording · Interactive pin guide · HTML source · Visualizer sketch

The saved visualizer sketch is a debugging aid; it is not the complete original V1.0 display firmware.

[blocked]

🌤️ V0.1 · Let there be light

TinkerCAD simulation · LDR input · LM339 comparators

The potentiometer input was replaced with an LDR, and the comparator section moved to LM339 devices. Now the input responded to light. The Uno still supplied both digital stages: deciding the encoded value and converting it into segment signals.

The sensor enters the picture. The display logic is still handled by the Uno.

Open this version: Simulation · Schematic PDF · Arduino sketch · BOM

[blocked]

🧪 V0.0 · Starting with a knob

TinkerCAD simulation · Potentiometer input · Arduino Uno

The first version used a potentiometer to stand in for the sensor voltage. Turning the knob changed the input to the comparator bank, while the Uno performed priority encoding and drove the seven-segment display. This established the basic voltage-to-level idea before adding a light-sensitive input.

The starting point. Click the circuit image to open its TinkerCAD simulation.

Open this version: Simulation · Schematic PDF · Arduino sketch · BOM

[blocked]

🎛️ Explore the project

Open the interactive TriBit Lux explorer →

The preview above is animated; the linked page is interactive. The explorer uses the updated V2.0 reference mapping, including the level-0 band. It models ideal logic, with real-world tolerances, noise and timing left out. Open the standalone HTML file.

[blocked]

🚧 What's next

The planned lights should make each level transition easier to see. The acrylic enclosure should make the circuit easier to display while providing secure mounting. Support components such as decoupling and protection remain electrically important whether their packages are THT or SMT.

[blocked]

📂 Finding your way around

TriBit-Lux/
├── README.md                    Illustrated project walkthrough
├── docs/media/                  Photo previews and video poster
├── Version_2.1/
│   ├── README.md                Hybrid board gallery, pinout and status
│   ├── TriBitLux_V2_1/          Editable KiCad project, schematic and PCB
│   ├── assets/                 XEMACS’s board renders and schematic image
│   ├── schematic/              Current netlist
│   ├── bom/                    Full and SMT-only parts lists
│   ├── cpl/                    Native and JLCPCB placement exports
│   └── review/                 Current checks and layout feedback
├── Version_2.0/                 Unfabricated through-hole milestone
├── Version_1.3/                 LCD build and demonstrations
├── Version_1.2/                 Hardware decoder and serial sketch
├── Version_1.1/                 Encoder build and EasyEDA archive
├── Version_1.0/                 First breadboard and pin visualizer
├── Version_0.1/                 LDR simulation
└── Version_0.0/                 Potentiometer simulation

Each version folder contains the records that survived that stage. Older versions may not contain a complete build package. The photographs, videos and interactive pages show the development process; the editable design files describe the circuit. KiCad temporary files and backups are excluded through .gitignore.

Built and documented by XEMACS
From a simulated input to a board designed around light.

Try the explorer · Back to the latest design · Repository