# Capacitor Symbol Types in KiCad

## For This Project: Use **UNPOLARIZED** Symbols

All capacitors in this design are **ceramic capacitors**, which are **unpolarized**.

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## 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

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## 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**

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## 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**

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## 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

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## 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

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## 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`**

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## 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


