Product Description

A trimmer or preset is a miniature adjustable electrical component. It is meant to be set correctly when
installed in some device, and never seen or adjusted by the device's user. Trimmers can be variable
resistors (potentiometers), variable capacitors, trimmable inductors. 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 and rated
for many fewer adjustments over their lifetime. Trimmers like trimmable inductors and trimmable capacitors
are usually found in superhet radio and television receivers, in the Intermediate frequency, oscillator and RF
circuits. They are adjusted into the right position during the alignment 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 ***2, Marlan Bourns patented the world's first trimming potentiometer, trademarked "Trimpot", a name
now commonly used to refer to any trimming potentiometer