ESP_Midea/Midea_ESP/CAPACITOR_SYMBOLS.md

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