1. Single-Turn Trimmers

A single-turn trimmer allows the wiper to travel through its complete resistance range with approximately one rotation of the adjustment screw.

• Simple construction
• Quick adjustment
• Low cost
• Widely used for general calibration

They are suitable when the circuit does not require extremely fine adjustment.

2. Multi-Turn Trimmers

A multi-turn trimmer requires several rotations of the adjustment screw to move through its complete resistance range.

• Very fine adjustment
• Better control of small changes
• Useful for precision circuits
• Common in measurement and calibration equipment

Because the adjustment is spread over several turns, it is easier to make small changes to the resistance.

3. Through-Hole Trimmers

Through-hole trimmers have terminals designed to pass through holes in a printed circuit board (PCB).

• Easy to identify and handle
• Suitable for conventional PCB assembly
• Available in many resistance values
• Common in older and general-purpose equipment

4. SMD Trimmers

SMD trimmers are designed for surface-mount circuit boards. They occupy little PCB space and can be installed using automated assembly processes.

• Compact size
• Suitable for modern PCBs
• Low board space requirement
• Available in single-turn and multi-turn designs

Because of their small size, adjustment can require a suitable precision tool.

5. Top-Adjustment Trimmers

With a top-adjustment trimmer, the adjustment screw is accessible from the top of the component.

This arrangement is useful when the trimmer is mounted on a PCB and the technician needs access from above.

• Easy access after PCB installation
• Common in compact electronic equipment
• Available in different resistance values

6. Side-Adjustment Trimmers

A side-adjustment trimmer has its adjustment mechanism located on the side of the component.

This can be useful when the component is positioned where access from the side is more convenient.

• Useful for specific PCB layouts
• Allows adjustment from the side
• Available in compact packages

7. Carbon Trimmers

Carbon trimmers use a carbon-based resistive element. They are generally intended for low-cost general-purpose adjustment applications.

• Low cost
• Compact construction
• Suitable for general calibration

8. Cermet Trimmers

Cermet trimmers use a ceramic-metal resistive element and are widely used where improved stability and precision are required.

• Good stability
• Good resistance accuracy
• Suitable for calibration
• Available in single-turn and multi-turn versions

9. Wirewound Trimmers

Wirewound trimmers use resistive wire as the adjustment element. They can provide useful electrical characteristics for certain applications, although their construction differs from carbon and cermet designs.

• Resistive wire element
• Good power-handling capability in suitable designs
• Used in specialized applications

Comparison of Trimmer Types

How to Choose a Trimmer

Select the trimmer according to the requirements of the circuit. Consider:

• Resistance value → must match the circuit requirement
• Adjustment range → determines the available variation
• Number of turns → choose multi-turn for finer adjustment
• Mounting type → through-hole or SMD
• Adjustment direction → top or side access
• Power rating → must be suitable for the circuit
• Stability → important for precision circuits

Single-Turn or Multi-Turn?

Important Notes

• Not all trimmers have the same adjustment range.
• Check the datasheet before selecting a replacement.
• Consider both electrical and mechanical dimensions.
• Use a suitable adjustment tool to avoid damaging the mechanism.
• For precision circuits, stability and adjustment resolution are important.