A trimmer or preset[1] 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.

Since 1990 , Kingtronics International company founded its first factory in mainland of China . For 20 years development and experience in manufacturing timpots , Kingtronics brand is well known by more and more pepole .

Now Kingtronics offer Bourns equivalence: 3006, 3266, 3296,  3323, 3329, 3362, 3386,3309, 3540, 3590 . If you want more details ,please visit website: www.kingtronics.com for full specification.