A Trimmer is a small (miniature) like potentiometer which is used for adjustment, tuning and calibration or recalibration in electronic/electrical circuits. It can be also be called preset resistor when it is wired as a rheostat or trimpots. Preset resistor are usually mounted on printed circuit boards and it is adjusted by using screwdriver. It is designed for infrequent adjustment as the lifespan is often only 200 cycles.The most commonly used resistive element in trimmer is either carbon composition or cermet.
Types Of Trimmers
There are different types of trimmers available in the market which have different mounting methods(through smd and hole), adjusting orientations (top or side) as well as single and multi-turn variations.
Single Turn Trimmer
Single turn trimmers are very common and are usually used where a resolution of one turn is enough. They are one of the cheapest variable resistors available.
Multi Turn Trimmer
Multi turn trimmer are used for higher adjustment resolutions. it takes several turns of the adjustment screw to reach the end value. The numbers of turns varies between 5-25, but the most common are 5, 12 or 25 turns. They are made by using a worm-gear (rotary track) or leadscrew (linear track) mechanism to achieve the high resolution. They are more expensive than single turn trimmers due to their more complex construction and manufacturing.The lead screw packages can have a higher power rating due to their increased surface area.