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🔍 Parallel Resistance Finder

Find the best E-series resistor pair to match a target parallel resistance.

Search Parameters

📏 Selected Parallel Pair

Resistor R₁
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Resistor R₂
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Parallel Result (Center)
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📊 Matching Error
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⚠️ RSS Error
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⚠️ Worst-Case Error
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📈 Total Effective Range (Matching + Tolerance)

RSS Method (Statistical)
Minimum Possible Value
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Maximum Possible Value
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Worst-Case Method (Conservative)
Minimum Possible Value
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Maximum Possible Value
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📋 Candidate Pairs

Click any row to see detailed error analysis above

How It Works

Parallel Resistance Formula: Rtotal = (R₁ × R₂) / (R₁ + R₂)

Error Analysis:

  • Matching Error: How closely the parallel combination matches your target
  • RSS Error: Statistical error from component tolerances (√(Σ(∂R/∂Rᵢ × ΔRᵢ)²))
  • Worst-Case Error: Maximum possible error (Σ|∂R/∂Rᵢ × ΔRᵢ|)
  • Total Effective Range: The actual possible range considering both matching error and component tolerances

Example: Target 1kΩ with 1% resistors → Best pair: 2.2k || 2.2k = 1.1kΩ
Matching: +10%, RSS Tolerance: ±1.41% → Total range: +8.59% to +11.41% (1085.9Ω to 1114.1Ω)

R₁ R₂ Matching Error
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