Variable trimmer capacitors are types of adjustable capacitors(devices that store electrical charge in circuits) where the capacitor capacitance (its ability to store an electrical charge) can be readily adjusted. They're often used in LC circuits (circuits that have an inductor and a capacitor) to set the frequency, for example, to tune a radio.
RS offer a range of high-quality ceramic and PTFE dielectric trimmer capacitors from industry-leading brands including Murata, Vishay and of course RS PRO.
Trimmer capacitors are used to initially set oscillator frequency values, rise and fall times and other variables in a circuit. Should the values drift over time, trimmer capacitors allow you to re-calibrate your equipment.
Variable trimmer capacitors are almost always mounted directly on a PCB (printed circuit board) and set by using a small screwdriver. Variable trimmer capacitors are usually cheaper than full-sized variable capacitors.
Common applications include oscillators, tuners, crystal oscillators and filters. Trimmer capacitors can also be found in communication equipment such as mobile radios and aerospace transmitters. Trimmer capacitors are available in SMD or through-hole mounting types and come in a range of voltages and capacitive ranges.