Resistor Similarity Calculator Skill

Guidance for working with ResistorSimilarityCalculator in the lib-electronic-components library.

For metadata-driven similarity architecture, see /similarity-metadata:

SpecImportance levels (CRITICAL, HIGH, MEDIUM, LOW, OPTIONAL)
ToleranceRule types (exactMatch, percentageTolerance, minimumRequired, etc.)
SimilarityProfile contexts (DESIGN_PHASE, REPLACEMENT, COST_OPTIMIZATION, etc.)
Calculator integration patterns and gotchas

Overview

The ResistorSimilarityCalculator compares resistors based on:

Package size (0.3 weight) - 0402, 0603, 0805, etc.
Resistance value (0.5 weight) - 10K, 100R, 4.7K, etc.

Maximum similarity is 0.8 (not 1.0) since tolerance and other specs aren't always extractable.

Applicable Types

ComponentType.RESISTOR
ComponentType.RESISTOR_CHIP_VISHAY
ComponentType.RESISTOR_CHIP_YAGEO
ComponentType.RESISTOR_CHIP_PANASONIC
ComponentType.RESISTOR_CHIP_BOURNS
// Any type starting with "RESISTOR_"

Similarity Scoring

| Condition | Score | |-----------|-------| | Same value, same package | 0.8 | | Same value, different package | 0.5 | | Same package, different value | 0.3 | | Different value, different package | 0.0 |

Value Extraction

The calculator extracts resistance values from MPNs:

| MPN | Extracted Value | |-----|-----------------| | CRCW060310K0FKEA | 10K (10kΩ) | | RC0603FR-0710KL | 10K (10kΩ) | | ERJ3GEYJ103V | 10K (103 = 10×10³) |

Package Size Extraction

Common package codes in MPNs:

| Pattern | Package | |---------|---------| | 0603 | 0603 (1608 metric) | | 0805 | 0805 (2012 metric) | | 1206 | 1206 (3216 metric) |

Cross-Manufacturer Matching

The calculator can match equivalent resistors across manufacturers:

// Vishay 0603 10K vs Yageo 0603 10K
calculator.calculateSimilarity("CRCW060310K0FKEA", "RC0603FR-0710KL", registry);
// Returns >= 0.5 (both are 10K, may have same package)

Test Examples

// Same Vishay resistor - max similarity
calculator.calculateSimilarity("CRCW060310K0FKEA", "CRCW060310K0FKEA", registry);
// Returns 0.8

// Same value, different package
calculator.calculateSimilarity("CRCW060310K0FKEA", "CRCW080510K0FKEA", registry);
// Returns 0.5

// Same package, different value
calculator.calculateSimilarity("CRCW0603100RFKEA", "CRCW060310K0FKEA", registry);
// Returns 0.3 (100R vs 10K)

Implementation Notes

Returns 0.0 for null MPNs or null registry
Returns 0.0 for empty strings
Handles unrecognized formats gracefully (returns 0.0-1.0)

Learnings & Quirks

Value Notation

E96 notation: 103 = 10×10³ = 10kΩ, 4R7 = 4.7Ω
Yageo TCR code -07 is NOT a separator, it's temperature coefficient

Package Extraction

Some MPNs embed package in series name (e.g., RC0603)
Others have separate position (e.g., CRCW + 0603)