← Quick Reference Charts
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Electrical
Resistor color code, wire gauge, wire color codes, connector torque, capacitor reference, metric prefixes, dB reference, and unit conversions.
Metric Prefixes
| Prefix | Symbol | Power | Example |
|---|---|---|---|
| Tera | T | 10¹² | 1 THz = 1,000,000 MHz |
| Giga | G | 10⁹ | 1 GHz = 1,000 MHz |
| Mega | M | 10⁶ | 1 MHz = 1,000 kHz |
| Kilo | k | 10³ | 1 kHz = 1,000 Hz |
| Base | — | 10⁰ | 1 Hz, 1 V, 1 A, 1 W |
| Milli | m | 10⁻³ | 1 mA = 0.001 A |
| Micro | μ | 10⁻⁶ | 1 μF = 0.000001 F |
| Nano | n | 10⁻⁹ | 1 nF = 0.001 μF |
| Pico | p | 10⁻¹² | 1 pF = 0.001 nF |
Decibel Quick Reference
| dB | Power Ratio | Voltage Ratio | Meaning |
|---|---|---|---|
| 0 dB | 1:1 | 1:1 | No change |
| +1 dB | 1.26:1 | 1.12:1 | Slight increase |
| +2 dB | 1.58:1 | 1.26:1 | Minor increase |
| +3 dB | 2:1 | 1.41:1 | Double power |
| +6 dB | 4:1 | 2:1 | 4x power, 2x voltage |
| +10 dB | 10:1 | 3.16:1 | 10x power |
| +20 dB | 100:1 | 10:1 | 100x power |
| +30 dB | 1,000:1 | 31.6:1 | 1,000x power |
| -3 dB | 0.5:1 | 0.707:1 | Half power |
| -6 dB | 0.25:1 | 0.5:1 | Quarter power |
| -10 dB | 0.1:1 | 0.316:1 | 10% of power |
| -20 dB | 0.01:1 | 0.1:1 | 1% of power |
Resistor Color Code
Mnemonic: Big Brown Rabbits Often Yield Great Big Values Good Work
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
Black | 0 | ×1 | — |
Brown | 1 | ×10 | ±1% |
Red | 2 | ×100 | ±2% |
Orange | 3 | ×1k | — |
Yellow | 4 | ×10k | — |
Green | 5 | ×100k | ±0.5% |
Blue | 6 | ×1M | ±0.25% |
Violet | 7 | ×10M | ±0.1% |
Gray | 8 | ×100M | ±0.05% |
White | 9 | ×1G | — |
Gold | — | ×0.1 | ±5% |
Silver | — | ×0.01 | ±10% |
AWG Wire Gauge Reference
| AWG | Diameter | Resistance | Max Current |
|---|---|---|---|
| 0 | 8.25 mm | 0.322 Ω/km | 150 A |
| 2 | 6.54 mm | 0.513 Ω/km | 95 A |
| 4 | 5.19 mm | 0.815 Ω/km | 70 A |
| 6 | 4.11 mm | 1.30 Ω/km | 55 A |
| 8 | 3.26 mm | 2.06 Ω/km | 40 A |
| 10 | 2.59 mm | 3.28 Ω/km | 30 A |
| 12 | 2.05 mm | 5.21 Ω/km | 20 A |
| 14 | 1.63 mm | 8.29 Ω/km | 15 A |
| 16 | 1.29 mm | 13.2 Ω/km | 13 A |
| 18 | 1.02 mm | 20.9 Ω/km | 10 A |
| 20 | 0.812 mm | 33.3 Ω/km | 7.5 A |
| 22 | 0.644 mm | 53.0 Ω/km | 5 A |
| 24 | 0.511 mm | 84.2 Ω/km | 3.5 A |
Wire Color Codes
| Standard | Wire Color | Meaning |
|---|---|---|
| Automotive (aftermarket stereo, EIA) | Black | Ground / negative return |
| Automotive (aftermarket stereo, EIA) | Red | Switched (ignition/accessory) power |
| Automotive (aftermarket stereo, EIA) | Yellow | Battery constant positive (memory) |
| Automotive (aftermarket stereo, EIA) | Green | Left rear speaker positive |
| Automotive (aftermarket stereo, EIA) | White | Left front speaker positive |
| Automotive (aftermarket stereo, EIA) | Gray | Right front speaker positive |
| Marine (ABYC) | Yellow/Red stripe | Engine starting circuit |
| Marine (ABYC) | Red | DC positive (ungrounded conductor) |
| Marine (ABYC) | Black or Yellow | DC negative (grounded conductor) |
| Marine (ABYC) | Green or Green/Yellow | DC grounding conductor |
| Marine (ABYC) | Dark Blue | Cabin and instrument lights |
| Marine (ABYC) | Brown | Generator armature, alternator charge light, pumps |
| Aviation (AS50881 / MIL-W-5088) | White | Standard insulation color — circuits are identified by printed wire ID codes, not by color |
| Aviation (AS50881 / MIL-W-5088) | Colored | Thermocouple leads and some special cables use specific colors — follow the aircraft wiring manual |
| AC Mains (US NEC) | Black | Hot (line) |
| AC Mains (US NEC) | White | Neutral |
| AC Mains (US NEC) | Green or Bare | Safety ground |
| AC Mains (US NEC) | Red | Second hot (240V / 3-phase) |
Imperial to Metric Conversions
| Imperial | Metric |
|---|---|
| 1 inch | 25.4 mm |
| 1 foot | 304.8 mm / 0.3048 m |
| 1 yard | 914.4 mm / 0.9144 m |
| 1 mile | 1.609 km |
| 1 nautical mile | 1.852 km |
| 1 statute mile | 1.609 km |
| 1 oz | 28.35 g |
| 1 lb | 453.6 g / 0.4536 kg |
| 1 psi | 6.895 kPa |
| 1 ft-lb | 1.356 N·m |
| 1 in-lb | 0.113 N·m |
| 1 horsepower | 746 W |
| 1 BTU | 1055 J |
| °F to °C | (°F − 32) × 5/9 |
| °C to °F | (°C × 9/5) + 32 |
RF Connector Torque
Typical coupling-nut torque. Always use the connector manufacturer's specification when available.
| Connector | Torque | Notes |
|---|---|---|
| N-type | 12–15 in·lb / 1.4–1.7 N·m | Do not overtighten |
| TNC | 12–15 in·lb / 1.4–1.7 N·m | Threaded version of BNC |
| SMA | 7–10 in·lb / 0.8–1.1 N·m (8 in·lb typical) | Small threads — easy to strip |
| BNC | No torque | Bayonet lock — push and twist |
| PL-259 (UHF) | Hand tight | Do not wrench tighten |
| 7/16 DIN | 220–265 in·lb / 25–30 N·m | High-power base station |
Capacitor Value Codes
Three-digit codes: the first two digits are the value and the third is the number of zeros, in picofarads (104 = 10 × 10⁴ pF = 100 nF).
| Value | Code | Typical Use |
|---|---|---|
| 1 pF | 010 | RF tuning, stray capacitance compensation |
| 10 pF | 100 | RF circuits, crystal oscillator load |
| 22 pF | 220 | Crystal load capacitor (common) |
| 100 pF | 101 | RF bypass, HF decoupling |
| 1 nF (1000 pF) | 102 | High frequency bypass |
| 10 nF (0.01 µF) | 103 | General bypass, audio filtering |
| 100 nF (0.1 µF) | 104 | Power supply decoupling — most common bypass cap |
| 1 µF | 105 | Audio coupling, low frequency bypass |
| 10 µF | 106 | Power supply filtering, audio coupling |
| 100 µF | — | Power supply bulk filtering (electrolytic) |
| 1000 µF | — | Power supply reservoir (electrolytic) |
| 10,000 µF | — | Large power supply reservoir (high-current supplies, audio amplifiers) |