similarity-resistor

name	similarity-resistor
description	Use when working with resistor similarity calculations - comparing resistor MPNs, understanding value/tolerance/package matching, or implementing resistor-specific similarity logic.

Resistor Similarity Calculator Skill

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

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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

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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)

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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)