Cheat Sheet
Circuitbuilding Do-It-Yourself For Dummies
If you want to try your hand at building circuits or other electronics, make sure you keep the right tools on hand, know how to read resistor color codes and the value markings for capacitors, and understand the metric system of units and voltage conversions.
Circuitbuilding and Resistor Color Codes
Resistors are common passive electronic parts (meaning they don't need power to run) for circuitbuilding. Resistors control currents and voltages and they're manufactured in a variety of ways. Use this table to read resistor color codes for circuitbuilding:
Color | Value Stripe | Multiplier Stripe | Tolerance Stripe |
---|---|---|---|
Black | 0 | times; 1 (10^{0}) | |
Brown | 1 | times; 10 (10^{1}) | 1% |
Red | 2 | times; 100 (10^{2}) | 2% |
Orange | 3 | times; 1000 (10^{3}) | |
Yellow | 4 | times; 10,000 (10^{4}) | |
Green | 5 | times; 100,000 (10^{5}) | 0.5% |
Blue | 6 | times; 1,000,000 (10^{6}) | 0.25% |
Violet | 7 | times; 10,000,000 (10^{7}) | 0.1% |
Gray | 8 | times; 100,000,000 (10^{8}) | 0.05% |
White | 9 | times; 1,000,000,000 (10^{9}) | |
Gold | times; 0.1 | 5% | |
Silver | times; 0.01 | 10% | |
No color | 20% |
How to Read Capacitor Value Markings
When you’re building circuits with capacitors, you’ll need to learn to read the value markings, which not only designate values but other parameters as well.
###L (Three numbers and a letter) | Numbers 1 and 2 are value digits. |
Number 3 is a multiplier: 0 = × 1, 1 = × 10, 2 = × 100, 3 = × 1000, 4 = × 10,000. | |
Letter denotes tolerance: J = 5%, K = 10%, L = 20% | |
##p or ##n | Numbers 1 and 2 are value digits. |
p denotes pF, n denotes nF. |
Drill Sizes Commonly Used in Electronics
Building circuits and other electronics requires a small electric drill, cordless or not. Invest in a small bench-mount drill press if you're installing circuits in project boxes and cabinets so it looks good. This guide shows you drill sizes you'll need:
Size Number | Diameter | Next Largest Fractional Size | Clears Screw Size | For Self-Tapping Screw Size |
---|---|---|---|---|
11 | 0.191″ | 13/64″ | 10 | |
19 | 0.166″ | 11/64″ | 8 | |
21 | 0.159″ | 11/64″ | 10-32 | |
25 | 0.149″ | 5/32″ | 10-24 | |
28 | 0.140″ | 9/64″ | 6 | |
29 | 0.136″ | 9/64″ | 8-32 | |
33 | 0.113″ | 1/8″ | 4 | |
36 | 0.106″ | 7/64″ | 6-32 | |
43 | 0.089″ | 3/32″ | 4-40 | |
44 | 0.086″ | 3/32″ | 2 | |
50 | 0.070″ | 5/64″ | 2-56 |
Metric System Unit Prefixes
For building circuits or other electronics, a system of prefixes is used to make managing and reading metric easier. Use this chart to learn the metric prefix, its symbol, and the decimal value.
Prefix | Symbol | Multiplication Factor |
---|---|---|
tera- | T | 10^{12} |
giga- | G | 10^{9} |
mega- | M | 10^{6} |
kilo- | k | 10^{3} |
centi- | c | 10^{–}^{2} |
milli- | m | 10^{–}^{3} |
micro- | m | 10^{–}^{6} |
nano- | n | 10^{–}^{9} |
pico- | p | 10^{–}^{12} |
Voltage Conversions
Here are some handy mathematical formulas to help you figure out what those waveforms mean, and how to convert them to other measurements, when you're measuring voltage in your batteries or other electronic devices.
Sine or square wave | V_{PEAK-TO-PEAK} = 2 × V_{PEAK} |
Sine wave | V_{RMS} = 0.707 × V_{PEAK}, V_{PEAK} = 1.414 × V_{RMS} |
Square wave | V_{RMS} = V_{PEAK} |
Power to decibels | dB = 10 log_{10} (Power 1 / Power 2) |
Voltage to decibels | dB = 20 log_{10} (Voltage 1 / Voltage 2) |
Decibels to power | Power 1 = Power 2 × antilog_{10} (dB / 10) |
Decibels to voltage | Voltage 1 = Voltage 2 × antilog_{10} (dB / 20) |