| Revision as of 23:43, 1 August 2005 editLight current (talk | contribs)30,368 edits removed int link from heading← Previous edit | Revision as of 18:29, 2 August 2005 edit undoLight current (talk | contribs)30,368 edits tuned amplifiers exist-- so removed last part of introNext edit → | ||
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| An '''amplifier''' can be considered to be ''any'' ] that uses a small amount of energy to control a larger amount, althoug the term today usually refers to an ] amplifier. The relationship of the input to the output of an amplifier--usually expressed as a function of the input frequency--is called the ] of the amplifier, and the magnitude of the transfer function is termed the ]. | An '''amplifier''' can be considered to be ''any'' ] that uses a small amount of energy to control a larger amount, althoug the term today usually refers to an ] amplifier. The relationship of the input to the output of an amplifier--usually expressed as a function of the input frequency--is called the ] of the amplifier, and the magnitude of the transfer function is termed the ]. | ||
| Amplifiers are typically utilized over a specific range of frequencies and are generally of maximal utility if the gain is constant in that range.<br /> | |||
| == Electrical Relays == | == Electrical Relays == | ||
Revision as of 18:29, 2 August 2005
An amplifier can be considered to be any device that uses a small amount of energy to control a larger amount, althoug the term today usually refers to an electronic amplifier. The relationship of the input to the output of an amplifier--usually expressed as a function of the input frequency--is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain.
Electrical Relays
Relays can be included under the above definition of amplifiers although their transfer function is not linear.(ie they are either open or closed).
Electronic Amplifiers
The most common type of amplifier is the electronic amplifier, commonly used in radio and television transmitters and receivers, high-fidelity ("hi-fi") stereo equipment, microcomputers and other electronic digital equipment, and guitar and other instrument amplifiers. Its critical component is an active device, such as a vacuum tube or transistor.
Transistor Amplifers
Most common actice devices in transistor amplifiers are bipolar junction transistors (BJTs); metal oxide semiconductor field-effect transistors (MOSFETs) are also used. The essential role of this active element is to magnify an input signal to yield a significantly larger output signal. The amount of magnification (the "forward gain") is determined by the external circuit design as well as the active device.
Vacuum Tube (Valve)Amplifiers
In the earlier years of audio, vacuum tubes filled the active device role.
Operational Amplifiers (OP-AMPS)
An Operational Amplifier is a solid state integrated circuit amplifier which employs external feedback for control of its transfer function or gain See also: low noise amplifier.
Other Amplifier Types
There are also mechanical amplifiers, such as the automotive servo used in braking. Another type of amplifier is the fluidic amplifier, based on the fluidic triode.
External links
- The Audio Circuit - Information on and user reviews of loudspeakers, headphones, amplifiers, and playback equipment