What are trimmer potentiometers?

Trimmer potentiometers, sometimes referred to as trim pots or trimmer resistors are a type of adjustable potentiometer (variable resistor). They are used to calibrate and fine-tune circuits. Trimmer potentiometers are typically constructed from cermet or have a carbon composition. They can be mounted directly onto PCBs (printed circuit boards).

Trimmer potentiometers are not adjusted very frequently. You can think of them as a set and forget component. Trim pots let you set (or trim) the resistance to obtain a very precise current, output voltage or gain. Once the value has been set, it is unlikely that youll need to adjust the trimmer again unless you need to recalibrate the circuit.

Can I replace a normal potentiometer with a trimmer potentiometer?

Yes, you can. However, trimmer potentiometers are typically more expensive than standard potentiometers with a fixed resistance rating. It is also worth bearing in mind the difference in lifespan too. Many potentiometers have a lifespan that allows for hundreds of thousands of cycles. Trimmer potentiometers typically have a lifespan of a few hundred cycles (at best). Trim pots also tend to take up more space on a PCB than a standard potentiometer.

Do I need a single turn or multiturn trim pot?

This completely depends on the intended application of the trim pot. Multiturn trimmer pots tend to have a higher resolution than single turn models. A single turn trimmer potentiometer is ideal for applications where a resolution of one turn is enough.

Adjustment types

Trimmer potentiometers are normally adjusted by hand (you can turn the adjustment knob with your fingers), with a screwdriver or with a specialised adjustment tool designed for use with a particular model or series.