Trimmer Capacitors

What is a trimmer capacitor?

Trimmer capacitors are variable capacitors which serve the purpose of initial calibration of equipment during manufacturing or servicing. They are not intended for end-user interaction. Trimmer capacitors are almost always mounted directly on the PCB (Printed Circuit Board), so the user does not have access to them, and set during manufacturing using a small screwdriver. Due to their nature, trimmer capacitors are cheaper than full sized variable capacitors and rated for many fewer adjustments.

Trimmer capacitors are used to initially set oscillator frequency values, latencies, rise and fall times and other variables in a circuit. Should the values drift over time, these trimmer capacitors allow repairmen to re-calibrate equipment when needed. There are two types of trimmer capacitors: air trimmer capacitor and ceramic trimmer capacitor.

Examples of our trimmer capacitors

We offer film dielectric trimmers for impedance matching circuits. These allow for easy adjustment of resistance values through physical manipulation Applications include medical, consumer electronics, and industrial.

Another example is a radial leaded film dielectric trimmer capacitor with top and bottom adjustment. The Vishay BFC2 809 080 series assists energy conversion while providing low losses, high efficiency and long life. Plastic film trimmers reduce microphony effects and are suited for impedance matching RF circuits.

They consist of a polysulphone housing, brass rotor and plated brass stator with PTFE film as the dielectric. The stator plate tags are heat sealed to the housing. The rotor contact surfaces are plated to ensure a long life and a stable contact even under severe climatic conditions. A coloured dot indicates the maximum capacitance. Flux absorption between the vanes is prevented.

Applications include communications & networking, medical, and RF communications

Padder capacitors

A padder is a trimmer capacitor inserted in series with the oscillator tuning circuit of a superheterodyne receiver to control calibration at the low frequency end of a tuning range.