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Interpreting Results

Interpreting Calculation Results

Understanding what the calculator's output values mean and how to use them for practical circuit construction. This page helps you translate numbers into actionable design decisions.

Understanding Output Values

Inductance Results

Output Typical Range What It Means
L (inductance) 1-100 mH Primary choke property, affects f₀ and Q
DCR 0.1-50 Ω Wire resistance, major Q limiter
SRF 50 kHz - 1 MHz Maximum usable frequency
Cparasitic 10-500 pF Stray capacitance, determines SRF
Wire Length 1-50 m Total wire needed for winding

Capacitance Results

Output Typical Range What It Means
Cwfc 1-100 nF WFC capacitance, sets resonance with L
Rsolution 0.1-100 Ω Water resistance, affects Q
Z₀ (characteristic) 100-10,000 Ω √(L/C), impedance at resonance

Circuit Results

Output Typical Range Interpretation
f₀ (resonant freq) 1-100 kHz Where circuit resonates naturally
Q factor 5-200 Resonance sharpness, voltage gain
Bandwidth 50 Hz - 5 kHz Usable frequency range around f₀
Vmagnification 5× - 200× Voltage gain at resonance
Ring-down τ 0.1-10 ms Decay time constant
Ring-down cycles 3-150 Oscillations during decay

What "Good" Values Look Like

✓ Well-Designed VIC Circuit:

  • Q factor: 30-100 (good balance of gain vs. stability)
  • f₀: Within your driver's frequency range
  • Operating frequency: < 30% of SRF (preferably < 10%)
  • Primary/Secondary f₀ match: Within 5-10%
  • Bandwidth: Wide enough to accommodate drift
  • Voltage magnification: As needed for your application

✗ Warning Signs:

  • Q < 10: Very low—circuit barely resonates
  • Q > 300: Extremely sharp—hard to tune, sensitive to drift
  • fop > 0.5 × SRF: Operating too close to SRF
  • DCR > Z₀/10: Resistance dominates, poor Q
  • Primary/Secondary mismatch > 20%: Poor energy transfer

Translating Results to Construction

Wire Length and Turns

The calculator provides wire length and turn count. When winding:

  • Add 10-20% to wire length for lead connections and margins
  • Count turns carefully—L varies as N², so turn count is critical
  • Verify L after winding—actual may differ from calculated

Component Selection

Calculated Value Selection Guidance
C1 = 47.3 nF Use 47 nF standard value (within 1%)
C1 = 31.2 nF Use 33 nF or parallel 22+10 nF
L = 15.7 mH Wind for 16 mH, fine-tune with parallel C

Understanding Accuracy Limits

Know what to expect from calculated vs. measured values:

Parameter Expected Accuracy Why Variation Occurs
Inductance ±10-20% Core μᵣ varies, winding geometry imperfect
DCR ±5% Wire tables accurate, but length varies
SRF ±30% Parasitic C is hard to model precisely
Cwfc ±15% Fringe effects, water purity variation
Rsolution ±20% Conductivity varies with temperature
f₀ (calculated) ±15% Depends on L and C accuracy
Q factor ±25% Multiple loss mechanisms combine

Comparing Calculated vs. Measured

When Measured f₀ is Lower Than Calculated:

  • Actual L is higher than calculated
  • Stray capacitance adding to Ctotal
  • WFC capacitance underestimated

When Measured f₀ is Higher Than Calculated:

  • Actual L is lower than calculated
  • Core saturation reducing effective L
  • WFC capacitance overestimated

When Measured Q is Lower Than Calculated:

  • Additional losses not accounted for (core loss, skin effect)
  • Poor connections adding resistance
  • Water conductivity different than assumed

Using Results for Troubleshooting

Observation Calculator Check Likely Issue
No resonance found Check SRF vs. operating frequency Operating above SRF
Very weak resonance Check calculated Q High losses, low Q
Resonance at wrong frequency Verify L and C inputs Input error or mismeasurement
Less voltage gain than expected Compare Q values Actual losses higher
Resonance drifts during use Check temperature effects Water heating, capacitance changing

Results Summary Checklist

Before building, verify these from your results:

  1. ☐ f₀ is within driver frequency range
  2. ☐ f₀ is < 30% of SRF (ideally < 10%)
  3. ☐ Q is in acceptable range (typically 20-150)
  4. ☐ Voltage magnification won't exceed component ratings
  5. ☐ Wire gauge handles expected current
  6. ☐ Primary and secondary frequencies are matched
  7. ☐ No warning indicators are present
  8. ☐ Results are saved for reference

Final Advice: The calculator gives you an excellent starting point. Always plan to measure your actual circuit and iterate. The goal is to get close enough that minor tuning (adjusting C1, trimming frequency) achieves optimal performance.

Chapter 7 Complete. Next: Advanced Topics →

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