Electronic Components

Overview

Electronic components are devices used to build circuits.

NOTE: This page should likely be updated to better include lists of components, probably catagorized in a similar manner to this wikipedia page.

Recommended online tool for creating parts lists:

If you are in the process of choosing components for a PCB design, or just a breadboard circuit, you may find the following free online site super useful to both help you find components and to compile and list of components. This is an online service offered by JLC PCB, of course there are many other companies form which components can be sources and PCB fabrication performed, this link is mainly give as it can be rather useful in speeding up the selection and construction of a parts list. See: JLC PCB SMD Assembly Component Catalogue

Capacitors

Types of Capacitors

Electrolytic capacitors are polarised but ceramic caps are not.

Reading Capacitors

Most capacitors have number codes if the capacitor is too small to have the full value written on it. It is usually a three number code where the last number is the multiplier similar to resistors. The base numbers are in pF (picoFarad).

For example, the label "332" is 33*10^{2} = 3300 pF = 3.3 nF

Resistors

Resistors are common electronic components that provide resistance in circuits, thereby controlling the current, adjusting the signal amplitude, dividing the voltage, biasing active elements, terminating transmission lines and so on. Resistors are one of the earliest electrical attributes discovered, almost at the same time as the discovery of electric current. Different materials have different resistance properties, for example, copper, aluminum and gold are considered good conductors (low resistance), stainless steel, carbon, tungsten are considered medium conductors (medium resistance), and ceramics, mica and air are considered poor conductors (high resistance). Ohm’s law defines the relationship between circuit attributes: Resistance = Voltage / Current Resistance = Power / ( Current^2 ) In addition to the ohmic attribute, resistance can also be defined as a function of noise voltage, as part of Noise Power = kTBf, where a resistor above absolute zero temperature is a source of noise. When a resistor is combined with a capacitor or an inductor, the current through this network will be out of phase with the applied voltage, and called displacement current. The combination of resistance with capacitance / inductance is known as impedance, and complex mathematics is used to build on the basic ohm’s law shown above.

History of resistors

According to some sources , we can learn some facts about the history of resistors:

In 1827, Georg Simon Ohm invented the resistor at the University of Erlangen. Ohm was a mathematician who published many research papers on heat conduction in molded circuits and presented the ohm’s law. In 1872, ohm was determined as the unit of measuring resistance. In 1893, the first carbon film fixed resistor was exhibited at the Chicago World’s Fair. In 1906, Walter Schottky invented the metal film fixed resistor. In 1925, Otto Feist invented the metal foil fixed resistor. In the 1930s, variable and precision resistors began to appear. In 1961, Walter Boykin obtained a patent for improving the manufacturing method and structure of carbon film fixed resistors. Since the 1970s, with the development of surface mount technology and integrated technology, various types and specifications of resistors with smaller size and higher performance have appeared.

Resistance = (First ring × 10 + Second ring) × Third ring × 10^(-2) Ω

Tolerance = ±(Fourth ring × Resistance)

For example：

a four-band resistor whose colors are red, purple, brown and gold has a resistance value of：

Resistance = (2×10+7)×10×10^(-2) Ω = 270 Ω

Tolerance = ±(0.05×270) Ω = ±13.5 Ω

Resistor color code chart for beginners

Potentiometers

Pots also have 3 number codes with the third being a multiplier. The base value is in Ohms.

For example, the label "103" is 10*10^{3} = 10 kilo Ohms