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Trimmer (electronics)
Encyclopedia
Potentiometer
A potentiometer , informally, a pot, is a three-terminal resistor with a sliding contact that forms an adjustable voltage divider. If only two terminals are used , it acts as a variable resistor or rheostat. Potentiometers are commonly used to control electrical devices such as volume controls on...
s), variable capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
s, trimmable inductor
Inductor
An inductor is a passive two-terminal electrical component used to store energy in a magnetic field. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries...
s. They are common in precision circuitry like A/V components, and may need to be adjusted when the equipment is serviced. Unlike many other variable controls, trimmers are mounted directly on circuit boards, turned with a small screwdriver
Screwdriver
A screwdriver is a tool for driving screws and often rotating other machine elements with the mating drive system. The screwdriver is made up of a head or tip, which engages with a screw, a mechanism to apply torque by rotating the tip, and some way to position and support the screwdriver...
and rated for many fewer adjustments over their lifetime. Trimmers like trimmable inductor
Inductor
An inductor is a passive two-terminal electrical component used to store energy in a magnetic field. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries...
s and trimmable capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
s are usually found in superhet radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
and television
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
receivers, in the Intermediate frequency
Intermediate frequency
In communications and electronic engineering, an intermediate frequency is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception. The intermediate frequency is created by mixing the carrier signal with a local oscillator signal in a process called...
, oscillator and RF circuits. They are adjusted into the right position during the alignment
Alignment
Alignment may refer to:* Alignment , secondary evidence used to associate features such as postholes* Alignment , in Israel from 1965 to 1992...
procedure of the receiver.
Trimmers come in a variety of sizes and levels of precision; for example, multi-turn trim potentiometers exist, in which it takes several turns of the adjustment screw to reach the end value, allowing for very high degrees of accuracy.
In 1952, Marlan Bourns
Bourns, Inc.
Bourns, Inc. is a private, global electronics corporation that develops, manufactures and supplies a wide range of electronic components for a variety of industries including automotive, industrial, instrumentation, medical electronics, consumer equipment, computers and peripherals,...
patented the world's first trimming potentiometer, trademarked "Trimpot", a name now commonly used
Genericized trademark
A genericized trademark is a trademark or brand name that has become the colloquial or generic description for, or synonymous with, a general class of product or service, rather than as an indicator of source or affiliation as intended by the trademark's holder...
to refer to any trimming potentiometer.