Electronic Projects for Beginners – Reading Components (Part III)

The focal point of the first two installments of this multi-part series was an overview of basic components necessary to complete electronic projects. Part III focuses on learning about components and how to read the values and the schematic representation.

Different components have different methods of reading the values. Some have color codes and others have an array of numbers to decipher.

Resistors

These components often have up to five bands of color, each referring to a specific number. The image to the right is an example of a color code chart. As seen in the picture, black refers to zero; brown refers to one; red refers to two, etc. Most resistors have four distinct color bands. The first and second color refers to specific numbers, while the third band refers to the multiplier. Once you have the numbers, you can use this basic equation to find the value of the resistance (measured in ohms, Ω):

#­₁ #₂ #₃ = #₁ #₂ *10^#₃

For example: Red Black Orange = 20,000Ω

Here is how it is broken down:

Red (#­₁) = 2; Black (#₂) = 0; Orange (#₃) = 3

20*10^3 = 20,000 Ohms = 20,000Ω

The image at left is the schematic representation of a resistor. This is how resistors will appear in circuit schematics in future blog entries.

Capacitors

Electrolytic and tantalum capacitors have their values written on them. It seems easier to find the value on electrolytic capacitors than on tantalum capacitors. Mar Vac Electronics has a handy how-to webpage for deciphering tantalum capacitors.

The schematic representation of these polarized capacitors is shown at left. The "+" on the diagram corresponds to the "+" lead on the capacitor. The other side denotes the "-" lead on the capacitor.

Ceramic capacitors have three digits and then a letter (which denotes tolerance). The first two digits are significant digits and the third is a multiplier (similar to resistors, only this time there is no deciphering of the color codes). It is ideal to use this basic equation to find capacitance (measured in farads, F):

#­₁ #₂ #₃ = #₁ #₂ *10^#₃

For Example: 104 = 10*10^4 pF = .1μF

Mar Vac Electronics has another handy how-to webpage on how to decipher ceramic capacitors.

The schematic representation for these components is shown at right. Note that unlike the electrolytic and tantalum capacitors, this representation of a capacitor has no "+" sign. Just like a ceramic capacitor, the leads can be connected in any orientation without concern.

Potentiometers

Reading these devices is almost identical to that of a ceramic capacitor, only there is no letter to denote tolerance right next to the letters. Like resistors, the unit of measure for a potentiometer is ohms, Ω. For Example: 504 = 50*10^4 = 500,000 Ohms = 500,000Ω

The schematic symbol for potentiometers can be viewed at the left and right side. The projects in this series will use the left symbol more often.

SI Prefixes on Units

A lot of schematics use SI prefixes for values in order to save space (for example: 1000Ω = 1*10^3Ω = 1kΩ). Giga (G), mega (M), and kilo (k) are prefixes most often used for resistance. Milli (m), micro (μ), nano (n), and pico (p) are most often used for capacitance.

After reading such a long introduction, it may seem like a mountain of obstacles that electrical engineers must endure to complete circuits. This may hold true for some projects, but in the case of this blog series, rest assured that everything will be thoroughly explained. Pictures will be provided in ample amounts to assist the building process.

Part IV of this series will focus on turning a schematic from what may look like a bunch of symbols on paper, into a functioning circuit on a breadboard.

Previous Blogs in Series:

Electronic Projects for Beginners – Components (Part I)

Electronic Projects for Beginners – More Components (Part II)