Do trimmer capacitors have polarity?
Since trim caps are variable capacitors, they come in a capacitance range rather than a single capacitance value. It is worth noting that trimmer capacitors are not polarized.
How do you hook up a 3 pin variable capacitor?
For polarised capacitors, you connect them together the same way you would wire batteries together.
- Parallel. Connect positive terminals together. Connect negative terminals together. See fig 15 below.
- Series. Connect the positive terminal of one to the negative terminal of another. See fig 16 below.
What are the three wires on a capacitor?
On many systems these terminals may be labeled so that the three leads on a start/run capacitor can be wired correctly: S = start wire connector. R = Run wire connector. C = common connector.
Does it matter which way round you connect a capacitor?
Always take care to connect electrolytic capacitors the correct way round because they may explode when reversed.
Where are variable capacitors used?
Variable capacitors are often used in L/C circuits to set the resonance frequency, e.g. to tune a radio (therefore it is sometimes called a tuning capacitor or tuning condenser), or as a variable reactance, e.g. for impedance matching in antenna tuners.
Where are the capacitors located on a trimmer?
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.
What does a trimmer capacitor do on a PCB?
A trimmer capacitor is a variable capacitor used for initial calibration and recalibration of equipment. It is commonly mounted directly on a PCB and accessed only by professional repairmen, not the end-user.
What’s the capacitance tolerance for a trimmer capacitor?
It is worth noting that trimmer capacitors are not polarized. Trimmer capacitors do not boast a good capacitance value tolerance. Sometimes, the tolerances can be as high as -0 to +100%. This means that a trimmer capacitor can have a maximum capacitance two times larger than nominal.
What kind of dielectric is used in trimmer capacitors?
The dielectric used could be air or ceramic. Trimmer capacitors can be made of semi-circular metal plates. One of the plates is fixed while the other can be rotated using a screwdriver. The capacitance changes when the shaft is rotated thereby increasing or reducing the amount of overlap between the two plates.