Initial KiCad project

Midea_ESP/CAPACITOR_SYMBOLS.md

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+# Capacitor Symbol Types in KiCad
+
+## For This Project: Use **UNPOLARIZED** Symbols
+
+All capacitors in this design are **ceramic capacitors**, which are **unpolarized**.
+
+---
+
+## Capacitor Types in This Design
+
+### C1, C2: 10µF Capacitors
+- **Type:** Ceramic (X7R or X5R)
+- **Symbol:** **Unpolarized** (non-polar)
+- **KiCad Symbol:** `Device:C` (standard capacitor symbol)
+- **Package:** 0805
+
+### C3, C4, C5-C13: 100nF Capacitors
+- **Type:** Ceramic (X7R)
+- **Symbol:** **Unpolarized** (non-polar)
+- **KiCad Symbol:** `Device:C` (standard capacitor symbol)
+- **Package:** 0805
+
+---
+
+## Polarized vs Unpolarized Capacitors
+
+### Unpolarized Capacitors (Ceramic)
+- **Symbol:** Two parallel lines (no + or - marking)
+- **KiCad Symbol:** `Device:C`
+- **Types:** Ceramic, Film, Mica
+- **Can be connected either way** - no polarity
+- **Used in this project:** All capacitors (C1-C13)
+
+### Polarized Capacitors (Electrolytic)
+- **Symbol:** One curved line (negative) and one straight line (positive)
+- **KiCad Symbol:** `Device:CP` (polarized capacitor)
+- **Types:** Aluminum electrolytic, Tantalum
+- **Must be connected correctly** - has + and - terminals
+- **NOT used in this project**
+
+---
+
+## How to Add Capacitors in KiCad
+
+### Step 1: Add Symbol
+1. Press `A` (Add Symbol)
+2. Search for: `Device:C` (unpolarized capacitor)
+3. Place on schematic
+
+### Step 2: Set Value
+1. Press `E` (Edit) on the capacitor
+2. Set **Value** field:
+   - C1, C2: `10µF` or `10uF`
+   - C3-C13: `100nF` or `0.1µF`
+
+### Step 3: Set Reference
+- KiCad will auto-assign references (C1, C2, etc.) when you annotate
+
+---
+
+## Visual Guide
+
+### Unpolarized Capacitor Symbol (Use This)
+```
+    |  |
+    |  |
+    |  |
+```
+Two parallel lines - **no polarity marking**
+
+### Polarized Capacitor Symbol (Don't Use)
+```
+    |  |
+    |  |
+    +  |
+```
+One curved line (negative) - **has polarity**
+
+---
+
+## Why Ceramic Capacitors?
+
+**Advantages:**
+- ✅ Unpolarized (no orientation issues)
+- ✅ Small size (0805 package)
+- ✅ Low cost
+- ✅ Good for decoupling and filtering
+- ✅ No leakage current issues
+- ✅ Long lifespan
+
+**For 10µF capacitors:**
+- Ceramic capacitors in 0805 package are available up to 22µF
+- X7R or X5R dielectric provides good stability
+- 16V rating is sufficient for 5V input
+
+**For 100nF capacitors:**
+- Standard ceramic capacitor value
+- Excellent for high-frequency decoupling
+- Very common and inexpensive
+
+---
+
+## KiCad Symbol Library
+
+**Use this symbol:**
+- **Library:** `Device`
+- **Symbol Name:** `C` (Capacitor)
+- **Footprint:** `Capacitor_SMD:C_0805_2012Metric`
+
+**Do NOT use:**
+- `Device:CP` (Polarized Capacitor) - This is for electrolytic capacitors
+
+---
+
+## Summary
+
+| Capacitor | Value | Type | Symbol | KiCad Symbol |
+|-----------|-------|------|--------|--------------|
+| C1, C2 | 10µF | Ceramic | Unpolarized | `Device:C` |
+| C3, C4 | 100nF | Ceramic | Unpolarized | `Device:C` |
+| C5-C13 | 100nF | Ceramic | Unpolarized | `Device:C` |
+
+**All capacitors use the same unpolarized symbol: `Device:C`**
+
+---
+
+## Common Mistakes to Avoid
+
+❌ **Don't use:** `Device:CP` (polarized capacitor symbol)
+- This is for electrolytic capacitors
+- Has polarity markings (+ and -)
+- Not needed for ceramic capacitors
+
+✅ **Do use:** `Device:C` (unpolarized capacitor symbol)
+- Standard capacitor symbol
+- No polarity markings
+- Correct for all capacitors in this design
+
+---
+
+## When Would You Use Polarized Capacitors?
+
+Polarized capacitors (electrolytic) are typically used for:
+- Large capacitance values (>100µF)
+- Power supply filtering
+- When you need very high capacitance in a small volume
+
+**For this project:** Ceramic capacitors are sufficient and preferred because:
+- They're smaller
+- They're cheaper
+- They don't have polarity issues
+- They work well for decoupling and filtering
+
+