schemdraw-circuit-generator

Schemdraw Circuit Generator

Generate professional, publication-quality circuit diagrams using schemdraw Python library. Outputs to vector formats (SVG, PDF) or raster (PNG).

Quick Start Workflow

🎯 RECOMMENDED: Incremental Conversational Approach

This workflow builds diagrams step-by-step with visual confirmation at each stage. Use this for complex circuits or when starting fresh.

A. Connection List - Write explicit connection list showing all component pins B. Incremental Build Loop - Build one component/section at a time:

1. Add ONE component or connection (e.g., "IC only", "add GND connection", "add R1")

2. Execute - Run Python script and save SVG

3. Visual Check - Generate screenshot via HTML wrapper + headless browser

4. User Confirmation - Show screenshot, get approval before proceeding

5. REPEAT - Go back to step 1 for next component until circuit complete

   Why this works:

• Catches issues immediately when they occur
• Easy to debug single changes
• User can guide spacing, positioning, and layout decisions
• Prevents compound errors that are hard to untangle

C. Final Verification - Once all components added:

• Generate final screenshot
• Trace each connection from Step A connection list
• Verify all component values, labels, pin numbers present

D. Complete - Deliver connection list AND final diagram

---

⚡ ALTERNATIVE: All-at-Once Approach (Only for simple circuits or experienced users)

Use this workflow ONLY when:

• Circuit is simple (< 5 components)
• You have high confidence in layout
• User explicitly requests complete diagram in one shot

A. Connection List - Write explicit connection list showing all component pins B. Generate Complete Code - Create schemdraw code implementing ALL connections C. Execute - Run Python script and save SVG D. Visual Verification (MANDATORY) - Perform comprehensive visual assessment

• Generate screenshot via HTML wrapper + headless browser
• LIST ALL PROBLEMS FIRST (don't fix one-by-one - you'll forget issues!)
• Apply ALL fixes at once
• Confirm with fresh screenshot
• REPEAT until all problems resolved

E. Final Confirmation - Trace each signal path from connection list

• If violations found: Return to B with fixes
• If clean: Proceed to F

F. Complete - Deliver both connection list AND diagram

⚠️ Warning: All-at-once approach often requires multiple fix iterations for complex circuits. Incremental approach is more reliable.

Visual Verification Checklist (MANDATORY)

🚨 CRITICAL REALITY: Only Human Visual Feedback is Reliable

AI visual assessment is NOT reliable for layout verification. AI may report "all connections traceable" while humans see obvious layout problems. Therefore:

• ✅ Generate screenshots for HUMAN review - Always provide visual output
• ✅ Wait for human feedback - Don't make assumptions about visual quality
• ❌ Don't trust AI visual verification - It misses layout issues humans easily spot
• ❌ Don't claim "complete" without user confirmation - User must see and approve

The Human-Driven Verification Loop

This is like HTML+CSS development - requires human eyes to judge visual quality.

1. GENERATE SCREENSHOT - Create visual output for user to review
2. SHOW TO USER - Present screenshot and ask for feedback
3. LISTEN TO HUMAN FEEDBACK - User will identify spacing, overlap, or clarity issues
4. FIX BASED ON USER INPUT - Apply changes user requests
5. REPEAT - Generate new screenshot, show to user, iterate until approved

Key insight: Users see layout problems AI cannot detect. Trust human feedback over AI assessment.

Visual Verification Categories

1. Connection Visibility Test

"Technically connected" ≠ "Visually connected"

For each connection in your connection list:

• ✅ Can you visually TRACE the line end-to-end?
• ✅ Are junction dots visible at split points?
• ❌ Are lines overlapping IC edges? (Human can't see the connection!)
• ❌ Are lines hidden behind component bodies?
• ❌ Are connection points ambiguous?

Common failure: Line connects to IC pin at the edge of the IC box → looks disconnected even though code is correct.

Fix: Route connections AWAY from IC edges using Manhattan routing:

# ❌ WRONG - line touches IC edge, invisible
elm.Line().at(junction).to(ic.PIN)

# ✅ CORRECT - route away from edge first
elm.Line().at(junction).down(0.5)
elm.Line().left(SMALL_SPACING)  # Clear the IC edge
elm.Dot()
elm.Line().down(0.5)
elm.Dot()
elm.Line().right(SMALL_SPACING + 1.0)  # Now visible approaching pin

2. Label Overlap Detection

🚨 CRITICAL RULE: Labels must NEVER overlap component symbols

Common overlap zones:

• Labels on component symbols - ❌ FORBIDDEN (e.g., "10kΩ" text on resistor zigzag)
• Adjacent components on same signal path (R1 ↔ R2)
• IC center label ↔ pin labels (IC name ↔ VOUT)
• Component labels ↔ value labels
• Labels ↔ junction dots or lines

Visual test questions:

• ❌ Is label text sitting ON TOP of component symbol? (resistor, capacitor, inductor)
• ❌ Are any characters touching between different labels?
• ❌ Is label text crowded or cramped?
• ✅ Can you clearly read each label independently?
• ✅ Can you see the complete component symbol without text obscuring it?

Fix priority order:

1. First: Increase spacing - Most effective, cleanest solution

   HORIZONTAL_SPACING = 1.5  # Increase from 1.0
   VERTICAL_SPACING = 1.5    # Increase from 1.0
   SMALL_SPACING = 0.75      # Increase from 0.5
   

2. Second: Adjust label position - Change loc parameter

   # R1/R2 overlap example:
   elm.Resistor().label('R1\n10kΩ', loc='top', ofst=0.2)  # Push up
   elm.Resistor().label('R2\n1kΩ', loc='left')  # Move to opposite side
   

3. Third: Reduce font size - Only if spacing isn't feasible

   .label('U2\nLM2596S', fontsize=10)  # Reduce from 11
   

4. Fourth: Add offset - Fine-tune position

   .label('IC', ofst=-0.3)  # Shift left by 0.3 units
   

3. Line Overlap Detection

🚨 CRITICAL RULE: Lines touching IC edges = Connection ambiguity

Problem areas:

• Lines touching/overlapping IC box edges - ❌ FORBIDDEN ("Is this connected?" - impossible to tell!)
• Lines crossing component bodies
• Lines crossing other lines without junction
• Lines crossing ground symbols

Fix rules:

• NEVER use .to(ic.PIN) directly - creates line touching IC edge
• Use .at() to position connections explicitly
• Use Manhattan routing (horizontal → vertical → horizontal only)
• Add intermediate junction dots to clarify path
• Route around component bodies, not through them
• Leave visible gap between IC edge and incoming lines

Example - Correct IC connection:

# ❌ WRONG - line touches IC edge
elm.Line().at(junction).to(ic.VIN)

# ✅ CORRECT - visible gap before IC edge
elm.Line().at(junction).right(1.0)  # Stop BEFORE IC edge
# IC connects from current position automatically

4. Definition of "Complete"

A diagram is complete ONLY when:

• ✅ Code executes without errors
• ✅ SVG generates successfully
• ✅ USER has visually reviewed screenshot and approved (MOST IMPORTANT)
• ✅ USER confirms all connections are traceable
• ✅ USER confirms no visual issues (overlaps, spacing, clarity)
• ✅ Every item from connection list is verified in diagram

🚨 CRITICAL: Never claim "complete" without explicit user approval of visual output!

AI cannot reliably assess visual quality. Only human confirmation counts.

Screenshot Generation for USER Review

Purpose: Generate visual output for HUMAN evaluation, not AI assessment.

Use HTML wrapper + headless browser to create screenshots for user review:

# Generate SVG first
python3 /tmp/circuit.py

# Create HTML wrapper
cat > /tmp/view_diagram.html << 'EOF'
<!DOCTYPE html>
<html><head><meta charset="UTF-8"><title>Check</title>
<style>
body{margin:20px;background:white;display:flex;justify-content:center;align-items:center;min-height:100vh;}
svg{border:2px solid #333;max-width:100%;max-height:90vh;}
</style>
</head><body>
[Paste SVG content here]
</body></html>
EOF

# Capture screenshot
node $HOME/.claude/skills/headless-browser/scripts/headless-check.js \
  --url file:///tmp/view_diagram.html \
  --screenshot viewport

Then READ the screenshot and perform comprehensive visual assessment.

Common IC Connection Patterns (Context7 Reference)

When working with ICs, query context7 for proper connection syntax:

topic: "IC integrated circuit pin connection"
topic: "wire routing shapes manhattan"
topic: "element positioning at anchor"

Key IC patterns learned:

• IC connects via sequential flow - current position flows to first left pin automatically
• Use .at(ic.pinname) to start FROM a specific pin
• Use .at(junction) BEFORE routing TO a pin to avoid edge overlap
• Pin names are anchors: ic.VIN, ic.GND, ic.FB, ic.VOUT

Example of proper IC connection:

# Create junction BEFORE IC
elm.Dot()
pre_ic_junction = d.here

# IC connects automatically from current position (sequential flow)
ic = elm.Ic(pins=[...])

# Route from junction to IC pin explicitly
elm.Line().at(pre_ic_junction).down(1.0)
elm.Dot()
elm.Line().right(1.0)  # Now connects to IC.PIN visibly

Using Context7 for Documentation

CRITICAL: Schemdraw has extensive features. When you need specific syntax, advanced features, or uncommon components, use context7:

mcp__context7__get-library-docs(
  context7CompatibleLibraryID: "/cdelker/schemdraw",
  mode: "code",
  topic: "your specific topic"
)

When to use context7:

• Uncommon components not in references/components.md
• Advanced features (custom elements, annotations, etc.)
• Specific IC pinout configurations
• Latest API changes or new features
• Troubleshooting unusual errors

Examples:

• topic: "opamp operational amplifier circuits"
• topic: "transistor bjt npn pnp"
• topic: "wire routing shapes"
• topic: "seven segment display multiplexer"

Installation

pip install schemdraw

Dependencies: numpy, pillow (for PNG export), matplotlib (optional backend)

Core Concepts

Drawing Context

All diagrams use context manager:

import schemdraw
from schemdraw import elements as elm

with schemdraw.Drawing(file='output.svg') as d:
    elm.Resistor().label('1kΩ')
    elm.Capacitor().down().label('10µF')

Element Chaining

Elements chain sequentially, each picking up where last ended:

elm.Resistor().right().label('R1')  # Goes right
elm.Capacitor().down().label('C1')  # Goes down from R1's end
elm.Line().left()                    # Goes left from C1's end

Directional Methods

• .up(), .down(), .left(), .right() - Cardinal directions
• .theta(angle) - Arbitrary angle in degrees
• Optional length: .up(length=2)

Positioning

• .at(position) - Place at specific location or anchor
• .to(position) - Draw to endpoint
• .toy(y) / .tox(x) - Manhattan routing
• .anchor(name) - Set which part is positioned

Anchors

Elements have named connection points:

• Two-terminal: start, end, center
• Transistors: base, collector, emitter (BJT) or gate, drain, source (FET)
• Opamps: in1, in2, out, vd, vs
• ICs: Custom pin names

Labels

elm.Resistor().label('R1')                   # Simple label
elm.Resistor().label('$R_1$')                # LaTeX math
elm.Resistor().label('1kΩ', loc='bottom')   # Position
elm.Capacitor().label(('−', '$V_o$', '+'))  # Multiple (polarity)

Connections

• elm.Dot() - Junction (filled circle)
• elm.Dot(open=True) - Terminal (open circle)
• elm.Line() - Straight connection
• elm.Wire('shape') - Routed: '-|', '|-', 'N', 'Z'

Step-by-Step Workflow (Incremental Approach)

Step A: Create Connection List

CRITICAL: Start with explicit connection list, not the diagram.

Write every connection showing which pin connects to which:

Connections:
- +15V input → U2 (LM2596S) pin 5 (VIN)
- +15V input → C5 (100µF) → GND
- U2 pin 3 (ON) → +15V (always enabled)
- U2 pin 4 (VOUT) → Switching node
- Switching node → L1 (100µH) → +13.5V Output
- Switching node → D1 (SS34 cathode)
- D1 (SS34 anode) → GND
- +13.5V → C3 (470µF) → GND
- U2 pin 2 (FB) → R1 (10kΩ) → Tap
- Tap → R2 (1kΩ) → GND
- Tap → +13.5V (feedback sense)
- U2 pin 1 (GND) → GND

This list serves as the specification. The diagram must satisfy EVERY connection.

Step B: Incremental Build - Start with Foundation

CRITICAL: Build circuit incrementally, one component/connection at a time.

Typical build order:

1. Start with IC only (no connections)
2. Add power connections (VIN, ON pins to input rail)
3. Add ground connection
4. Add input decoupling capacitors
5. Add output stage (VOUT → switching node → L1 → output)
6. Add flyback diode and output capacitor
7. Add feedback network
8. Connect feedback to FB pin

Example - First iteration (IC only):

import schemdraw
from schemdraw import elements as elm

# Black foreground with transparent background (default)
with schemdraw.Drawing(
    font='Arial',
    fontsize=11,
    color='black',
    transparent=True
) as d:
    d.config(unit=3)

    # Iteration 1: IC only
    ic = elm.Ic(
        pins=[
            elm.IcPin(name='GND', pin='3', side='left', slot='1/3'),
            elm.IcPin(name='ON', pin='5', side='left', slot='2/3'),
            elm.IcPin(name='VIN', pin='1', side='left', slot='3/3'),
            elm.IcPin(name='FB', pin='4', side='right', slot='1/2'),
            elm.IcPin(name='VOUT', pin='2', side='right', slot='2/2'),
        ],
        edgepadW=2.5,
        edgepadH=0.8,
        pinspacing=1.0,
        leadlen=1.0
    ).label('U2\nLM2596S', loc='center', fontsize=10)

    d.save('/tmp/buck_converter.svg')

Step C: Execute and Verify

After EACH iteration:

1. Run the script:

   python3 /tmp/circuit_generator.py
   

2. Generate screenshot:

   cat > /tmp/view.html << 'EOF'
   <!DOCTYPE html>
   <html><head><meta charset="UTF-8"><title>Circuit Check</title>
   <style>
   body{margin:20px;background:white;display:flex;justify-content:center;align-items:center;min-height:100vh;}
   svg{border:2px solid #333;max-width:100%;max-height:90vh;}
   </style>
   </head><body>
   EOF
   cat /tmp/buck_converter.svg >> /tmp/view.html
   echo "</body></html>" >> /tmp/view.html
   node $HOME/.claude/skills/headless-browser/scripts/headless-check.js \
     --url file:///tmp/view.html --screenshot viewport
   

3. Show user the screenshot

4. Get user confirmation: "Looks good, add next component"

5. Update code for next iteration (e.g., add GND connection)

6. REPEAT steps C1-C5 until circuit complete

Step D: Conversational Build Loop

User guides the process:

• "Add GND connection next"
• "Connect the input rail"
• "Shorten that line by half"
• "Move the label to the right side"

You respond with:

• Code update for requested change
• Execute script
• Generate screenshot
• Show result
• Wait for next instruction

Benefits:

• User can correct spacing/positioning immediately
• Catches label overlaps before they compound
• Easy to adjust layout decisions in real-time
• No need to untangle complex multi-component issues

Step E: Final Verification

Once all components added and user confirms diagram looks complete:

1. Visual check: Generate final screenshot
2. Connection trace: Verify each connection from Step A list is present
3. Component verification: Check all values, labels, pin numbers
4. User approval: Get final confirmation

Step F: Deliver

Provide to user:

1. Connection list (from Step A)
2. Final SVG diagram (verified version)
3. Python code (for reproducibility)
4. Screenshot (for documentation)

Common Patterns

See references/patterns.md for copy-paste patterns:

• Voltage divider
• RC filter (low-pass, high-pass)
• Inverting/non-inverting opamp
• Transistor switch
• LED driver
• Buck converter
• Comparator
• And more...

Reference Documentation

components.md

Complete component library reference with syntax for all elements:

• Passive: Resistors, capacitors, inductors
• Semiconductors: Diodes, transistors (BJT/FET)
• Sources: Voltage, current, AC, batteries
• ICs: Opamps, logic gates, specialized ICs
• Power/Ground: Various ground and supply symbols
• Connections: Dots, lines, wires

patterns.md

Copy-paste code for common circuits:

• Simple circuits (voltage divider, RC filter, LED)
• Opamp configurations (inverting, non-inverting, buffer, comparator)
• Transistor circuits (switch, amplifier)
• Advanced circuits (H-bridge, oscillators)

best-practices.md

Guidelines for professional diagrams:

• Layout strategies
• Labeling conventions
• Connection techniques
• Readability tips
• Code organization
• Common mistakes to avoid

examples.md

Complete working examples:

• 555 timer LED blinker
• Inverting opamp with power
• Differential amplifier
• Common emitter amplifier
• H-bridge motor driver
• RC oscillator
• Natural language parsing tips

troubleshooting.md

Solutions to common problems:

• Installation and import issues
• Layout and positioning problems
• Label issues (Unicode, LaTeX)
• Connection problems
• Orientation issues
• Output problems
• Advanced issues

Best Practices (Learned from Real Usage)

1. Consistent Label Positioning for Vertical Components

Problem: Labels on vertical components (resistors, capacitors going up/down) need consistent positioning to avoid overlaps and maintain professional appearance.

Solution: Use loc='bot', ofst=0.5 pattern for all vertical components:

# For components going upward
elm.Capacitor().up(2.0).label('C3\n470µF\n25V', loc='bot', ofst=0.5)
elm.Ground().flip()  # Flipped ground at top

# For components going downward
elm.Resistor().down().label('R1\n10kΩ', loc='bot', ofst=0.5)
elm.Resistor().down().label('R2\n1kΩ', loc='bot', ofst=0.5)
elm.Ground()  # Normal ground at bottom

Why this works: loc='bot' anchors label at component's bottom reference point, ofst=0.5 shifts it right, positioning label cleanly on the right side of the component body without overlapping the symbol or connection lines.

2. IC Edge Padding for Label Clearance

Problem: IC center label (e.g., "U2 LM2596S") overlaps with pin labels on the right side.

Solution: Use adequate edgepadW parameter instead of label offsets:

ic = elm.Ic(
    pins=[...],
    edgepadW=2.5,  # Wider box prevents label overlap
    edgepadH=0.8,
    pinspacing=1.0,
    leadlen=1.0
).label('U2\nLM2596S', loc='center', fontsize=10)

Why this works: Widening the IC box is cleaner than using label offsets. Typical values: edgepadW=2.5 for ICs with 5+ pins.

3. Precise Junction Positioning

Problem: Need junction at exact midpoint for symmetrical connections.

Solution: Calculate position mathematically:

# For horizontal rail between two pins
junction_y = (ic.VIN[1] + ic.ON[1]) / 2

# Build entire rail at calculated height
elm.Dot(open=True).at((x_position, junction_y)).label('+15V', loc='left')
elm.Line().right(2.0)
elm.Dot()
# ... all elements at same Y coordinate

Why this works: Calculating exact coordinates ensures straight lines and symmetrical layout. No diagonal connections or misaligned junctions.

4. Proper Push/Pop Stack Management

Problem: Multiple branches require careful stack management to return to correct positions.

Solution: Track push/pop pairs systematically:

elm.Dot()
junction1 = d.here
d.push()  # Save junction1

# Branch 1
elm.Line().right(1.0)
elm.Dot()
junction2 = d.here
d.push()  # Save junction2

# Branch 2
elm.Line().right(1.0)
elm.Dot(open=True)

# Return to junction2
d.pop()  # Now at junction2

# Continue from junction2
elm.Line().down(0.5)
elm.Resistor()...

# Return to junction1
d.pop()  # Now at junction1

Rule: Every d.push() must have a matching d.pop(). Stack structure: LIFO (Last In, First Out).

5. Ground Symbol Orientation

Problem: Ground symbols appear upside-down when components go upward.

Solution: Use .flip() for upward-facing components:

# Component going UP - flip ground
elm.Capacitor().up(2.0)
elm.Ground().flip()  # Ground symbol at top, points down

# Component going DOWN - normal ground
elm.Resistor().down()
elm.Ground()  # Ground symbol at bottom, points down

Rule: Ground always "points down" toward earth. Flip when it's physically above the component.

6. User Correction Responsiveness

Problem: User says "NO!" or expresses frustration - you misunderstood the request.

Solution:

1. STOP immediately - Don't continue with wrong approach
2. Re-read user's EXACT words - What did they literally say?
3. Use exact parameters specified - "right side" means loc='right', not loc='left'
4. Show result immediately - Generate screenshot, don't assume it's correct
5. Wait for confirmation - Let user verify before proceeding

Example from session:

• User: "the RIGHT side of the capacitor symbol"
• Wrong: loc='left' (causes "NO!!!")
• Correct: loc='right' (what they literally requested)

7. Spacing Adjustments

Problem: User requests specific spacing changes during build.

Solution: Be responsive to spacing requests:

# User: "halve the line there"
elm.Line().right(1.0)  # Changed from 2.0

# User: "change distance 1 -> 0.5 for each line"
elm.Line().down(0.5)  # Changed from 1.0
elm.Resistor()...
elm.Line().down(0.5)  # All spacing changed consistently

Why this matters: Small spacing adjustments (0.5 vs 1.0) significantly impact readability and label overlap prevention.

Quick Tips

1. Black foreground with transparent background - Always use font='Arial', color='black', transparent=True for web documentation
2. Start simple - Use patterns from patterns.md as starting point
3. Query context7 - For components/features not in references
4. Save references - Assign elements to variables: Q1 = elm.BjtNpn()
5. Use dots - Always at T-junctions, open dots for terminals
6. Check anchors - Use correct anchor names for element type
7. Manhattan routing - Use .toy() and .tox() for clean lines
8. Increase spacing - d.config(unit=3) if too cramped
9. SVG format - Best for documentation (vector, scalable)
10. Consistent labels - Use loc='bot', ofst=0.5 for vertical components
11. Listen carefully - When user corrects you, use their EXACT words

Output Formats

# SVG (recommended - vector, scalable)
with schemdraw.Drawing(
    file='circuit.svg',
    font='Arial',
    fontsize=11,
    color='black',
    transparent=True
) as d:
    d.config(unit=3)
    # ... components ...

# PNG (raster, for compatibility)
# Note: Generate SVG first, then save as PNG
d.save('circuit.png', dpi=300, transparent=True)

# PDF (for print)
with schemdraw.Drawing(
    file='circuit.pdf',
    font='Arial',
    fontsize=11,
    color='black',
    transparent=True
) as d:
    d.config(unit=3)
    # ... components ...

Black Foreground with Transparent Background (Default)

All diagrams should use black foreground with transparent background by default:

with schemdraw.Drawing(
    font='Arial',         # Sans-serif font
    fontsize=11,
    color='black',        # Black foreground
    transparent=True      # Transparent background
) as d:
    d.config(unit=3)
    # ... components ...

Why transparent background with black foreground:

• Allows HTML container background to show through (e.g., custom background colors)
• Black lines and text are visible on light container backgrounds
• Works seamlessly with web-based documentation (Docusaurus, etc.)
• Professional appearance with clean contrast
• Integrates with any light-themed documentation

Solid background (if specifically requested):

# Dark theme with solid black background and white foreground
with schemdraw.Drawing(
    font='Arial',
    fontsize=11,
    color='white',
    bgcolor='black'
) as d:
    # ... components ...

# Light theme with solid white background and black foreground
with schemdraw.Drawing(
    font='Arial',
    fontsize=11,
    color='black',
    bgcolor='white'
) as d:
    # ... components ...

Example: Simple Voltage Divider

import schemdraw
from schemdraw import elements as elm

# Black foreground with transparent background (default)
with schemdraw.Drawing(
    file='voltage_divider.svg',
    font='Arial',
    fontsize=11,
    color='black',
    transparent=True
) as d:
    elm.SourceV().label('12V')
    elm.Line().right(d.unit/2)
    elm.Resistor().down().label('R1\n10kΩ')
    elm.Dot()
    d.push()
    elm.Line().right(d.unit/2).dot(open=True).label('Vout\n(6V)', 'right')
    d.pop()
    elm.Resistor().down().label('R2\n10kΩ')
    elm.Ground()

When to Use This Skill

• User requests circuit diagrams or schematics
• Publication-quality output needed
• Vector graphics (SVG/PDF) for documentation
• Complex circuits with ICs, opamps, logic
• Alternative to ASCII art diagrams
• Technical papers or presentations

When NOT to Use

• User specifically wants ASCII art (use ascii-circuit-diagram-creator instead)
• Quick sketches where quality doesn't matter
• No Python environment available