Electronics For Dummies
Electronics is more than just schematics and circuits. By using various components, such as resistors and capacitors, electronics allows you to bend electric current to your will to create an infinite variety of gizmos and gadgets. In exploring electronics, it may be useful for you to have a handy reference for Ohm’s Law and Joule’s Law, for calculations, or for determining the values of resistors and capacitors according to the codes that appear on their casings.
Electronics Calculations Using Ohm’s Law and Joule’s Law
Ohm’s Law and Joule’s Law are commonly used in calculations dealing with electronic circuits. These laws are straightforward, but when you’re trying to solve for one variable or another, it is easy to get them confused. The following table presents some common calculations using Ohm’s Law and Joule’s Law. In these calculations,
V = voltage (in volts)
I = current (in amps)
R = resistance (in ohms)
P = power (in watts)
Unknown Value Formula Voltage V = IR Current I = V/R Resistance R = V/I Power P = VI or P = V2/R or P = I2R
Electronics Resistor and Capacitor Color Code
In electronic circuits, the value of resistors and capacitors can often be determined by their color and by the digits and multipliers that appear on the casing. The following table outlines values for some common resistors and capacitors.
|Color||1st Digit||2nd Digit||Multiplier||Tolerance|
|Black||0||0||x 1||± 20%|
|Brown||1||1||x 10||± 1%|
|Red||2||2||x 100||± 2%|
|Orange||3||3||x 1,000||± 3%|
|Yellow||4||4||x 10,000||± 4%|
|Gold||x 0.1||± 5%|
|Silver||x 0.01||± 10%|
Electronics Capacitor Tolerance Code
In electronic circuits, the tolerance of capacitors can be determined by a code that appears on the casing. The code is a letter that often follows a three-digit number (such as 130Z). The following table outlines tolerance values for some common capacitors.
|B||± 0.1 pF|
|C||± 0.25 pF|
|D||± 0.5 pF|
Electronics Capacitor Value Reference
In electronic circuits, the value of capacitors can be determined by a two- or three-digit code that appears on the casing. The following table outlines values for some common capacitors. Note that two-digit values are in pico-farads and three-digit values are in microfarads.
|nn (a number from 01 to 99)||nn picofarads (pF)|