Trim Pot

A trimmer or preset is a miniature adjustable electrical component. It is meant to be set correctly wheninstalled in some device, and never seen or adjusted by the device's user. Trimmers can be variableresistors (potentiometers), variable capacitors, trimmable inductors. They are common in precision circuitrylike A/V components, and may need to be adjusted when the equipment is serviced. Unlike many othervariable controls, trimmers are mounted directly on circuit boards, turned with a small screwdriver and ratedfor many fewer adjustments over their lifetime. Trimmers like trimmable inductors and trimmable capacitorsare usually found in superhet radio and television receivers, in the Intermediate frequency, oscillator and RFcircuits. 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 potentiometersexist, in which it takes several turns of the adjustment screw to reach the end value, allowing for very highdegrees of accuracy.In 1952, Marlan Bourns patented the world's first trimming potentiometer, trademarked "Trimpot", a namenow commonly used to refer to any trimming potentiometer