# Circuit Diagram Specifications

This document provides **exact specifications** for creating 7 circuit diagrams that require manual attention for professional quality.

**Recommended tools:** LTspice, CircuitLab, Inkscape, KiCad schematic editor, or professional drawing software.

**Format:** PNG, 150 DPI minimum, white background

---

## Circuit 1: Geometry to Circuit Translation

**Filename:** `lessons/01-fundamentals/assets/geometry-to-circuit.png`
**Size:** 1000 x 600 px
**Referenced in:** fund-02 (Basic Circuit Model)

### Description
Side-by-side diagram showing physical geometry on left, equivalent circuit on right.

### Left Side: 3D Visualization (Conceptual)
```
[Sketch/photo showing:]
- Toroidal topload (or spherical)
- Cylindrical spark channel extending downward
- Ground plane at bottom
- Arrows/labels indicating:
  * C_mut (coupling between topload and spark)
  * C_sh (spark to ground)
```

**Note:** Can use simplified 2D side-view sketch if 3D is difficult.

### Right Side: Circuit Schematic

**Topology (CRITICAL - verify this is correct):**

```
Topload node
    |
    +----[C_mut]----+
    |               |
    +----[R]--------+
    |
    (Spark tip node)
    |
    [C_sh]
    |
   GND
```

**Component values to show:**
- R: Variable (or "R_spark")
- C_mut: "~8 pF" (typical)
- C_sh: "~6 pF" (typical)

**Layout guidelines:**
- Vertical orientation
- Clear node labels: "Topload", "Spark Tip", "GND"
- R and C_mut in parallel (side-by-side, same start/end nodes)
- C_sh in series below the parallel combination

**Alternative if parallel is hard:** Show as impedance block "Z_mut = R || C_mut"

---

## Circuit 2: Current Paths Diagram

**Filename:** `lessons/01-fundamentals/assets/current-paths-diagram.png`
**Size:** 1000 x 1200 px (vertical)
**Referenced in:** fund-07 (Measurement Port)

### Description
Complete Tesla coil schematic showing **all** current return paths.

### Schematic Components

**Primary circuit (left side):**
```
[AC Source] -→ [IGBT/Switch] -→ [C_pri] -→ [L_pri] -→ GND
```

**Secondary circuit (right side, magnetically coupled):**
```
L_sec (coil symbol, coupled to L_pri via k = 0.1-0.2)
   |
   +-- [C_topload] --|
   |                 |
   +-- [Spark]       |
   |                 |
   +-- [C_stray] ----+
   |
  GND
```

**Current paths to label (USE DIFFERENT COLORS):**
1. **I_spark** (RED): Through spark resistance
2. **I_displacement** (BLUE): Through C_topload to ground
3. **I_coupling** (GREEN): Primary-to-secondary capacitive coupling
4. **I_secondary** (PURPLE): Distributed capacitance along secondary
5. **I_base** (BLACK, THICK): Total current at secondary base

**Key annotation:**
```
I_base = I_spark + I_displacement + I_coupling + I_secondary + ...
```

**Mark measurement points:**
- Correct: "Measure here" at topload-to-ground (V_top / I_spark)
- Incorrect: "NOT here" with X at base (V_top / I_base)

### Layout Guidelines
- Primary on left, secondary on right
- Clear coupling indicator (dashed lines or k = 0.1-0.2)
- Use arrows for current directions
- Color code or use different line styles for each current path
- Legend showing which color = which current

---

## Circuit 3: Thévenin Equivalent Circuit

**Filename:** `lessons/02-optimization/assets/thevenin-equivalent-circuit.png`
**Size:** 800 x 600 px
**Referenced in:** opt-04 (Thévenin Calculations)

### Description
Simple Thévenin equivalent driving a spark load.

### Schematic

```
    +-------[R_th]-----[jX_th]------+
    |                                |
[V_th source]                   [Z_spark load]
    |                                |
    +--------------------------------+
```

**More detailed Z_spark:**
```
Z_spark can be shown as:
    [R_spark] in series with [jX_spark]
    OR
    [(R || C_mut) in series with C_sh]
```

**Component labels:**
- V_th: "350 kV" (typical value)
- R_th: "114 Ω" (typical)
- X_th: "-j2424 Ω" (typical, capacitive)
- Z_spark: "Variable"

**Annotations:**
- "Thévenin Equivalent" label on left side
- "Spark Load" label on right side
- Formula below: **P = 0.5|V_th|² Re{Z_spark} / |Z_th + Z_spark|²**

### Layout Guidelines
- Horizontal orientation, left to right
- V_th source on left
- R_th and X_th clearly in series
- Load impedance on right
- Clean, minimal style

---

## Circuit 4: Capacitive Divider Circuit

**Filename:** `lessons/03-spark-physics/assets/capacitive-divider-circuit.png`
**Size:** 600 x 800 px (vertical)
**Referenced in:** phys-07 (Capacitive Divider)

### Description
Shows voltage division across C_mut and C_sh.

### Schematic

```
V_topload (source)
    |
    +----[C_mut]----+
    |               |
    +----[R]--------+
    |
    V_tip (measurement point) ← mark this clearly
    |
    [C_sh]
    |
   GND
```

**Component labels:**
- V_topload: "Input"
- C_mut: "~10 pF"
- C_sh: "~6.6 L (pF)" where L is in meters
- R: "R_spark"
- V_tip: Mark with voltmeter symbol or arrow

**Key formula (below circuit):**
```
V_tip = V_topload × [C_mut / (C_mut + C_sh)]

C_sh grows with spark length: ~6.6 pF/m
```

### Layout Guidelines
- Vertical orientation
- Show V_tip measurement clearly (voltmeter symbol or highlighted node)
- Annotate that C_sh increases with length
- Clean parallel R||C_mut representation

---

## Circuit 5: Lumped Model Schematic

**Filename:** `lessons/04-advanced-modeling/assets/lumped-model-schematic.png`
**Size:** 800 x 600 px
**Referenced in:** model-01 (Lumped Model)

### Description
Clean, professional lumped spark model circuit.

### Schematic (Same topology as Circuit 1, but cleaner)

```
Port (Topload connection)
    |
    +----[R]--------+
    |               |
    +----[C_mut]----+
    |
    (Spark tip - internal node)
    |
    [C_sh]
    |
   GND
```

**Component values:**
- R: "50 kΩ (typical)"
- C_mut: "8 pF (typical)"
- C_sh: "6 pF (typical)"

**Annotations:**
- "Port" or "Topload Connection" at top
- "Internal Node" at spark tip
- Box or note: "Typical values at 200 kHz for 3-foot spark"

### Layout Guidelines
- Very clean, professional appearance
- Grid-aligned components
- Perfect parallel alignment for R || C_mut
- Clear port indication (terminal symbols)
- Minimal, uncluttered

---

## Circuit 6: Distributed Model Structure

**Filename:** `lessons/04-advanced-modeling/assets/distributed-model-structure.png`
**Size:** 1200 x 600 px (horizontal)
**Referenced in:** model-03 (Distributed Model)

### Description
Shows n-segment distributed model with proper transmission-line style layout.

### Schematic

**Horizontal cascade layout (recommended):**

```
Topload --[C_01]-- Node1 --[C_12]-- Node2 -- ... --[C_n-1,n]-- Node_n
           |                |                          |
         [R_1]            [R_2]                      [R_n]
           |                |                          |
        [C_1,gnd]        [C_2,gnd]                 [C_n,gnd]
           |                |                          |
          GND              GND                        GND
```

**Alternative vertical cascade** (if horizontal too wide):
```
Topload
   |
[C_01]
   |
Node 1 --[R_1]--
   |            |
[C_1,gnd]      (parallel)
   |
[C_12]
   |
Node 2 --[R_2]--
   |            |
[C_2,gnd]      (parallel)
   |
  ...
```

**Component labeling:**
- Show first 2 segments explicitly
- Use "..." for middle segments
- Show last segment (segment n)
- Label: "n = 5 to 20 segments (typically n = 10)"

**Capacitance matrix note:**
- Annotation: "(n+1) × (n+1) capacitance matrix"
- "Extracted from FEMM electrostatic analysis"

### Layout Guidelines
- Clear repeating pattern
- Ellipsis (...) to indicate continuation
- Symmetric, professional appearance
- Not too cluttered

---

## Circuit 7: Tesla Coil System Overview

**Filename:** `assets/shared/tesla-coil-system-overview.png`
**Size:** 1400 x 1000 px
**Referenced in:** Multiple lessons

### Description
Complete DRSSTC system diagram showing all major components.

### Schematic Components

**Primary tank circuit:**
```
[DC Bus] → [H-Bridge / IGBT switches] → [C_pri (MMC)] → [L_pri] → GND
                  ↑
            [Gate Driver]
                  ↑
            [Feedback/Control]
```

**Secondary resonator:**
```
L_sec (large coil symbol, coupled to L_pri via k)
   |
[C_topload]
   |
[Spark gap or streamer symbol]
   |
[Strike point / GND]
```

**Annotations:**
- Coupling coefficient: "k = 0.1 to 0.2"
- Primary frequency: "f_pri = f_resonant"
- Secondary resonance: "f_sec = 1/(2π√(L_sec × C_top))"
- Power flow arrows
- "DRSSTC" or "Double-Resonant Solid State Tesla Coil" title

**Components to show:**
- DC power supply
- Full bridge (4 IGBTs/MOSFETs) or half bridge
- MMC (multiple capacitors in series-parallel)
- Primary coil (few turns, heavy wire)
- Secondary coil (many turns, fine wire)
- Topload (toroid or sphere symbol)
- Spark/streamer
- Feedback path (CT or antenna back to controller)
- Ground connections

### Layout Guidelines
- Primary on left or bottom
- Secondary on right or top
- Clear separation of power vs signal paths
- Coupling indicated (dashed lines, double-headed arrow, or k annotation)
- Professional, complete system view
- Include legend if needed

---

## General Guidelines for All Circuits

### Style
- **Clean, professional appearance**
- Grid-aligned components
- Consistent component symbols (IEEE or European standard)
- Clear, readable labels (minimum 10pt font)
- No overlapping text or components
- White background

### Components Symbols
- Resistor: Standard zigzag (IEEE) or rectangle (IEC)
- Capacitor: Two parallel lines
- Inductor: Coil/loops
- Ground: Standard ground symbol
- AC source: Sine wave in circle
- Voltage source: Circle with +/- or V label

### Colors (if used)
- Use sparingly, only for clarity
- Current paths: different colors
- Otherwise: black on white for print compatibility

### Verification
**CRITICAL:** Before finalizing any circuit:
1. Verify topology matches spark-physics.txt equations
2. Check that parallel vs series connections are correct
3. Ensure component values are realistic (refer to physical-bounds.md)
4. Review against worked examples for consistency

---

## Priority Order

**High Priority (needed for core lessons):**
1. Circuit 5: Lumped Model Schematic
2. Circuit 4: Capacitive Divider
3. Circuit 3: Thévenin Equivalent

**Medium Priority:**
4. Circuit 1: Geometry to Circuit
5. Circuit 6: Distributed Model

**Low Priority (nice-to-have):**
6. Circuit 2: Current Paths (complex, can use text description initially)
7. Circuit 7: System Overview (general reference, not lesson-critical)

---

## Tools Recommendations

**Easy (recommended for quick creation):**
- **CircuitLab** (web-based, clean output)
- **LTspice** (free, professional, can export schematics)
- **Falstad Circuit Simulator** (web-based, can screenshot)

**Professional (for publication quality):**
- **KiCad Schematic Editor** (free, excellent output)
- **Inkscape** (manual drawing with circuit symbols)
- **Adobe Illustrator / Affinity Designer** (professional vector graphics)

**Advanced (if familiar with LaTeX):**
- **CircuiTikZ** + LaTeX (publication-quality output)

---

## Validation Checklist

Before considering a circuit "done":

- [ ] Topology verified against spark-physics.txt
- [ ] Component values realistic and labeled
- [ ] No overlapping elements
- [ ] Grid-aligned, professional appearance
- [ ] Clear node labels where needed
- [ ] Formula or key annotation included
- [ ] 150 DPI or vector format (scalable)
- [ ] White background, high contrast
- [ ] Filename matches specification
- [ ] Placed in correct assets directory

---

## Notes

- These specifications are based on analysis of spark-physics.txt
- Some topologies (especially parallel R||C_mut) are tricky - verify carefully
- When in doubt, consult reference physics document
- Can simplify complex parallel combinations as impedance blocks (Z = R||C) if clearer
- Professional quality > programmatic generation

**Created:** 2025-10-10
**Status:** Awaiting manual creation
**Current:** 0/7 circuits completed