Electronics [2]

Two digital voltmeters

The field of electronics is the study and use of systems that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. The design and construction of electronic circuits to solve practical problems is part of the fields of electronic engineering, and the hardware design side of computer engineering. The study of new semiconductor devices and their technology is sometimes considered as a branch of physics.

Electronic devices today

Electronic devices are used to perform a wide variety of tasks. The main uses of electronic circuits are the controlling, processing and distribution of information, and the conversion and distribution of electric power. Both of these uses involve the creation or detection of electromagnetic fields and electric currents. While electrical energy had been used for some time to transmit data over telegraphs and telephones, the development of electronics truly began in earnest with the advent of radio.

CAD/CAM of electronic circuits

Today's electronics engineers enjoy the ability to design circuits using premanufactured building blocks such as power supplies, resistors, capacitors, semiconductors (such as transistors), and integrated circuits. Electronic design automation software programs include schematic capture programs such as ORCAD , used to make circuit diagrams and printed circuit board layouts.

Electronic systems

One way of looking at an electronic system is to divide it into the following parts:

1. Inputs – Electronic or mechanical sensors (or transducers), which take signals (in the form of temperature, pressure, etc.) from the physical world and convert them into current/voltage signals.
2. Signal processing circuits – These consist of electronic components connected together to manipulate, interpret and transform the signals.
3. Outputs – Actuators or other devices (also transducers) that transform current/voltage signals back into useful physical form.

One example is a television set. Its input is a broadcast signal received by an antenna or fed in through a cable. Signal processing circuits inside the television extract the brightness, colour and sound information from this signal. The output devices are a cathode ray tube that converts electronic signals into a visible image on a screen and magnet driven audio speakers.

Electronic test equipment

• Ammeter, e.g. Galvanometer (Measure current)
• Ohmmeter, e.g. Wheatstone bridge (Measure resistance)
• Voltmeter (Measures voltage)
• Multimeter (Measures all of the above)
• Oscilloscope (Measures all of the above, except Ohm, as they change over time)
• Logic analyzer (Tests digital circuits)
• Spectrum analyzer (SA) (Measures spectral energy of signals)
• Vector signal analyzer (VSA) (Like the SA but it can also perform many more useful digital demodulation functions)
• Electrometer (Measures charge)
• Frequency counter (Measures frequency)
• Time-domain reflectometer for testing integrity of long cables

Electronic components

• Electronic components
• Electronic Devices and Circuits

Analog circuits

Most analog electronic appliances, such as radio receivers, are constructed from arrays of a few types of circuits.

• Analog computer
• Analog multipliers
• electronic amplifiers
• electronic filters
• electronic oscillators
• Phase-locked loops
• electronic mixers
• Power conversion
• Electronic Power Supply
• impedance matchers
• operational amplifiers
• comparators

Digital circuits

Computers, electronic clocks, and programmable logic controllers (used to control industrial processes) are constructed of digital circuits. Digital Signal Processors are another example.

Building-blocks:

• logic gates
• flip-flops
• counters
• registers
• multiplexers
• Schmitt triggers

Highly integrated devices:

• microprocessors
• microcontrollers
• DSP
• Field Programmable Gate Array

Mixed-signal circuits

Mixed-signal circuits, also known as hybrid circuits, are becoming increasingly common. Mixed circuits contain both analog and digital components. analog to digital converters and digital to analog converters are the primary examples. Other examples are transmission gates and buffers.

Heat dissipation

Heat generated by electronic circuitry must be dissipated to improve reliability. Techniques for heat dissipation can include heatsinks and fans for air cooling, and other forms of computer cooling such as liquid cooling for computers .

Noise

Associated with all electronic circuits is noise. Types of noise include

• Shot noise in resistors.
• Johnson-Nyquist noise (Thermal noise) in resistors.
• White noise
• 1/f noise (pink noise, or flicker noise)
• Gaussian noise

Electronics theory

• Mathematical methods in electronics
• Digital circuits
• Analog electronics

See also

• Electrical engineering
  • Electronic Devices and Circuits
  • Integrated circuit
  • Optoelectronics
  • Point-to-point construction
  • Printed circuit board
  • Semiconductor
  • Semiconductor device
  • transducer
  • Wire wrap
  • Cordwood construction
  • Signal theory
• Circuit diagram
• Computer engineering
  • Microelectronics
• Datasheet
• Mechatronics
• Electronics manufacturing
• List of electronics topics
• E-waste
• Fuzzy electronics

External links

Wikibooks has more about this subject:

Electronics

Tutorials and projects

• Electronics Infoline Directory for electronics projects.
• Basic Electronic Tutorials On DC, AC, Semiconductor and Digital Theory Extensive free tutorial material and store.
• Electronics tutorials Modest site, mostly focused on radio electronics, awkward layout.
• Williamson Labs' Electronics tutorial
• Ian Purdie's Electronics tutorials
• Iguana Labs' Electronics Tutorials and Kits
• Electronic Meanings and Acronyms
• Lessons in Electric Circuits – A free series of textbooks on the subjects of electricity and electronics.
• Radio-Electronics.Com Free information and resources covering radio and electronics
• A hobbyist wiki
• Circuit simulator with voltage and current visualization
• A comprehensive guide to making integrated circuits
• HyperPhysics
• "Talking Electronics" Great for amateurs, commercial kits.
• Electronic parts library
• Work Ready Electronics Free instructional online course materials for Community College Electronics Instructors and Students.

Some other good sites

• Endtas robotics community website with lots of free robotic projects. Do it yourself
• IEEE
• IEEE spectrum
• Electronix Express
• Electronics Discussions Web access to electronics related newsgroups.