Skills

legacy-circuit-mockups

Originally fromgithub/awesome-copilot
Installation
SKILL.md

Skill Paths

  • Workspace skills: .github/skills/
  • Global skills: C:/Users/LOQ/.codex/skills/ for Codex or C:/Users/LOQ/.agents/skills/ for the shared mirror

A skill for creating breadboard circuit mockups and visual diagrams for retro computing and electronics projects. This skill leverages HTML5 Canvas drawing mechanisms to render interactive circuit layouts featuring vintage components like the 6502 microprocessor, 555 timer ICs, EEPROMs, and 7400-series logic gates.

When to Use This Skill

  • User asks to create a breadboard layout or circuit mockup
  • User wants visualized component placement for legacy electronics
  • User needs diagrams for 6502, 555 timer, EEPROM, VIA, or 7400-series builds
  • User asks for educational electronics visuals or wiring diagrams
  • User is following retro-computing tutorials and needs visual references

Prerequisites

  • Understanding of component pinouts from bundled reference files
  • Knowledge of breadboard layout conventions (rows, columns, power rails)

Supported Components

Microprocessors & Memory

Component Pins Description
W65C02S 40-pin DIP 8-bit microprocessor with 16-bit address bus
28C256 28-pin DIP 32KB parallel EEPROM
W65C22 40-pin DIP Versatile Interface Adapter (VIA)
62256 28-pin DIP 32KB static RAM

Logic & Timer ICs

Component Pins Description
NE555 8-pin DIP Timer IC for timing and oscillation
7400 14-pin DIP Quad 2-input NAND gate
7402 14-pin DIP Quad 2-input NOR gate
7404 14-pin DIP Hex inverter (NOT gate)
7408 14-pin DIP Quad 2-input AND gate
7432 14-pin DIP Quad 2-input OR gate

Passive & Active Components

Component Description
LED Light emitting diode (various colors)
Resistor Current limiting (configurable values)
Capacitor Filtering and timing (ceramic/electrolytic)
Crystal Clock oscillator
Switch Toggle switch (latching)
Button Momentary push button
Potentiometer Variable resistor
Photoresistor Light-dependent resistor

Grid System

// Standard breadboard grid: 20px spacing
const gridSize = 20;
const cellX = Math.floor(x / gridSize) * gridSize;
const cellY = Math.floor(y / gridSize) * gridSize;

Component Rendering Pattern

// All components follow this structure:
{
  type: 'component-type',
  x: gridX,
  y: gridY,
  width: componentWidth,
  height: componentHeight,
  rotation: 0,  // 0, 90, 180, 270
  properties: { /* component-specific data */ }
}

Wire Connections

// Wire connection format:
{
  start: { x: startX, y: startY },
  end: { x: endX, y: endY },
  color: '#ff0000'  // Wire color coding
}

Step-by-Step Workflows

Creating a Basic LED Circuit Mockup

  1. Define breadboard dimensions and grid
  2. Place power rail connections (+5V and GND)
  3. Add LED component with anode/cathode orientation
  4. Place current-limiting resistor
  5. Draw wire connections between components
  6. Add labels and annotations

Creating a 555 Timer Circuit

  1. Place NE555 IC on breadboard (pins 1-4 left, 5-8 right)
  2. Connect pin 1 (GND) to ground rail
  3. Connect pin 8 (Vcc) to power rail
  4. Add timing resistors and capacitors
  5. Wire trigger and threshold connections
  6. Connect output to LED or other load

Creating a 6502 Microprocessor Layout

  1. Place W65C02S centered on breadboard
  2. Add 28C256 EEPROM for program storage
  3. Place W65C22 VIA for I/O
  4. Add 7400-series logic for address decoding
  5. Wire address bus (A0-A15)
  6. Wire data bus (D0-D7)
  7. Connect control signals (R/W, PHI2, RESB)
  8. Add reset button and clock crystal

Component Pinout Quick Reference

555 Timer (8-pin DIP)

Pin Name Function
1 GND Ground (0V)
2 TRIG Trigger (< 1/3 Vcc starts timing)
3 OUT Output (source/sink 200mA)
4 RESET Active-low reset
5 CTRL Control voltage (bypass with 10nF)
6 THR Threshold (> 2/3 Vcc resets)
7 DIS Discharge (open collector)
8 Vcc Supply (+4.5V to +16V)

W65C02S (40-pin DIP) - Key Pins

Pin Name Function
8 VDD Power supply
21 VSS Ground
37 PHI2 System clock input
40 RESB Active-low reset
34 RWB Read/Write signal
9-25 A0-A15 Address bus
26-33 D0-D7 Data bus

28C256 EEPROM (28-pin DIP) - Key Pins

Pin Name Function
14 GND Ground
28 VCC Power supply
20 CE Chip enable (active-low)
22 OE Output enable (active-low)
27 WE Write enable (active-low)
1-10, 21-26 A0-A14 Address inputs
11-19 I/O0-I/O7 Data bus

Formulas Reference

Resistor Calculations

  • Ohm's Law: V = I × R
  • LED Current: R = (Vcc - Vled) / Iled
  • Power: P = V × I = I² × R

555 Timer Formulas

Astable Mode:

  • Frequency: f = 1.44 / ((R1 + 2×R2) × C)
  • High time: t₁ = 0.693 × (R1 + R2) × C
  • Low time: t₂ = 0.693 × R2 × C
  • Duty cycle: D = (R1 + R2) / (R1 + 2×R2) × 100%

Monostable Mode:

  • Pulse width: T = 1.1 × R × C

Capacitor Calculations

  • Capacitive reactance: Xc = 1 / (2πfC)
  • Energy stored: E = ½ × C × V²

Color Coding Conventions

Wire Colors

Color Purpose
Red +5V / Power
Black Ground
Yellow Clock / Timing
Blue Address bus
Green Data bus
Orange Control signals
White General purpose

LED Colors

Color Forward Voltage
Red 1.8V - 2.2V
Green 2.0V - 2.2V
Yellow 2.0V - 2.2V
Blue 3.0V - 3.5V
White 3.0V - 3.5V

Build Examples

Build 1 — Single LED

Components: Red LED, 220Ω resistor, jumper wires, power source

Steps:

  1. Insert black jumper wire from power GND to row A5
  2. Insert red jumper wire from power +5V to row J5
  3. Place LED with cathode (short leg) in row aligned with GND
  4. Place 220Ω resistor between power and LED anode

Build 2 — 555 Astable Blinker

Components: NE555, LED, resistors (10kΩ, 100kΩ), capacitor (10µF)

Steps:

  1. Place 555 IC straddling center channel
  2. Connect pin 1 to GND, pin 8 to +5V
  3. Connect pin 4 to pin 8 (disable reset)
  4. Wire 10kΩ between pin 7 and +5V
  5. Wire 100kΩ between pins 6 and 7
  6. Wire 10µF between pin 6 and GND
  7. Connect pin 3 (output) to LED circuit

Troubleshooting

Issue Solution
LED doesn't light Check polarity (anode to +, cathode to -)
Circuit doesn't power Verify power rail connections
IC not working Check VCC and GND pin connections
555 not oscillating Verify threshold/trigger capacitor wiring
Microprocessor stuck Check RESB is HIGH after reset pulse

References

Detailed component specifications are available in the bundled reference files:

Documentation

Examples

Scripts

Cross-Client Portability

This skill is written to stay usable across GitHub Copilot, Claude Code, Codex, and Gemini CLI.

  • GitHub Copilot: keep the folder in a Copilot-visible skill or plugin path, or wrap the workflow as project instructions if the host does not support portable skill folders directly.
  • Claude Code: keep the folder in a local skills directory or a compatible plugin or marketplace source.
  • Codex: install or sync the folder into $CODEX_HOME/skills/<skill-name> and restart Codex after major changes.
  • Gemini CLI: this repository generates a project command named /skills:legacy-circuit-mockups from this skill. Rebuild commands with python scripts/export-gemini-skill.py legacy-circuit-mockups and then run /commands reload inside Gemini CLI.

MCP Availability And Fallback

No dedicated MCP server is required for the normal workflow in this skill.

  • If the current host lacks an equivalent tool surface, use the bundled scripts, standard shell or editor tooling, and the manual workflow already described in this skill.
  • Treat local verification as the fallback evidence path before closing the task.

Related Skills

Skill Relationship
canvas-design Canvas drawing techniques and visual design
excalidraw-diagram-generator Alternative diagram generation approach
Related skills

More from practicalswan/agent-skills

Installs
9
Repository
practicalswan/a…t-skills
GitHub Stars
3
First Seen
Feb 26, 2026
Security Audits
Gen Agent Trust HubPass
SocketPass
SnykPass