Color-Coded Resistors

When SpiceBook generates a schematic, resistors with parseable values render as IEEE zigzag symbols with color-coded segments matching the standard 4-band resistor color code.

How It Works

A resistor value like 1k (1000Ω) is decomposed into:

1st significant digit: 1 → Brown
2nd significant digit: 0 → Black
Multiplier: ×100 → Red
Tolerance: ±5% → Gold (default)

These colors are applied directly to the zigzag segments in the SVG, mimicking how a physical resistor looks.

Band-to-Segment Mapping

The IEEE zigzag symbol has 7 sub-segments. Each is assigned a color role:

Segment	Role	Color
0 (entry)	Wire	Default wire color
1	1st significant digit	Color band
2	2nd significant digit	Color band
3	Multiplier	Color band
4 (gap)	Physical spacing	Default wire color
5	Tolerance	Color band
6 (exit)	Wire	Default wire color

The entry/exit segments and the gap before the tolerance band use the default wire color. This mimics the physical spacing on a real resistor that indicates reading direction — you read bands from the end closest to the first band.

Color Code Reference

Digit	Color	Hex
0	Black	`#1a1a1a`
1	Brown	`#8B4513`
2	Red	`#cc0000`
3	Orange	`#ff6600`
4	Yellow	`#cccc00`
5	Green	`#006400`
6	Blue	`#0000cc`
7	Violet	`#7b1fa2`
8	Gray	`#555555`
9	White	`#e0e0e0`

Multiplier bands use the same color mapping (Black = ×1, Brown = ×10, Red = ×100, etc.).

Tolerance: Gold (±5%) is the default when no tolerance is specified.

Value Range

Color-coded rendering applies to resistor values between 0.01Ω and 1GΩ. Outside this range, or for parametric values (e.g., {R_val}), the resistor falls back to a standard monochrome zigzag.

Example

A 4.7k resistor renders with:

Yellow (4) — 1st digit
Violet (7) — 2nd digit
Red (×100) — multiplier
Gold (±5%) — tolerance

The result is immediately recognizable to anyone who’s read resistor bands by hand — the schematic tells you both the circuit topology and the component values at a glance.