# Circuit Analysis Expert

> Expert-level circuit analysis covering KVL, KCL, nodal and mesh analysis, Thevenin and Norton theorems, AC circuits, phasors, and frequency response.

- Skill: `luokai0/circuit-analysis-expert` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add luokai0/circuit-analysis-expert`
- Raw SKILL.md: https://api.skillmd.com/api/skills/luokai0/circuit-analysis-expert/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: luokai0 (https://skillmd.com/u/luokai0)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/luokai0/circuit-analysis-expert

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# Circuit Analysis Expert

## Before Starting
1. DC or AC circuit?
2. Linear or nonlinear components?
3. Time domain or frequency domain analysis?

## Core Expertise Areas

### DC Circuit Analysis
KVL: sum of voltages around any closed loop equals zero.
KCL: sum of currents entering any node equals zero.
Nodal analysis: assign node voltages, write KCL at each node.
Mesh analysis: assign mesh currents, write KVL around each mesh.
Superposition: response is sum of responses to each source acting alone.

### Thevenin and Norton
Thevenin: any linear circuit reduces to voltage source in series with resistance.
Norton: any linear circuit reduces to current source in parallel with resistance.
Thevenin voltage: open circuit voltage at output terminals.
Thevenin resistance: resistance seen at terminals with all independent sources zeroed.
Maximum power transfer: load resistance equals Thevenin resistance.

### AC Circuit Analysis
Phasors: complex representation of sinusoids, amplitude and phase in one number.
Impedance: Z = R + jX, complex resistance for AC circuits.
Capacitor impedance: Z = 1 divided by j omega C, decreases with frequency.
Inductor impedance: Z = j omega L, increases with frequency.
Power factor: cos of phase angle between voltage and current.

### Frequency Response
Transfer function: ratio of output to input phasor as function of frequency.
Bode plot: magnitude and phase of transfer function vs log frequency.
Poles and zeros: determine shape of frequency response.
Resonance: LC circuit resonant frequency omega = 1 over sqrt of LC.
Q factor: quality factor, ratio of resonant frequency to bandwidth.

## Best Practices
- Always define reference node before writing nodal equations
- Check dimensional consistency in all circuit equations
- Use complex power for AC power calculations
- Verify results with SPICE simulation for complex circuits

## Common Pitfalls
| Pitfall | Fix |
|---|---|
| Sign errors in KVL | Define current directions and voltage polarities consistently |
| Forgetting reactive power | Use apparent power S = P + jQ for AC systems |
| Wrong Thevenin resistance calculation | Zero independent sources before calculating |
| Ignoring initial conditions in transients | Include capacitor voltages and inductor currents |

## Related Skills
- electronics-expert
- control-systems-expert
- signal-processing-expert