Potentiometers

Potentiometers are passive components whose electrical resistance can be continuously adjusted by mechanical actuation, in contrast to a fixed resistance. They consist of an electrically insulating carrier on which the actual resistance material is applied and a movable contact for removal , also known as a grinder. Potentiometers always have at least three electrical connections , two for the start and end of the actual resistance track and one for the movable sliding contact.

This results in a fixed resistance on the one hand via the total resistance and a continuously adjustable resistance on the other hand through the mechanical division of the resistance path into variable partial resistances on the other. When a voltage is applied, this results in an adjustable voltage divider with corresponding partial voltages.

Potentiometers are used whenever a manual control is to be implemented. Examples are the speed settings for power tools, volume and sound settings on audio devices, the regulation of an output voltage or the brightness level of the lighting via a dimmer. Another very common application of potentiometers is the internal adjustment of electrical and electronic circuits via the variable resistance value or by the use as a voltage divider.

In mechanical terms, potentiometers are distinguished between rotary and sliding potentiometers. A subset of the rotary potentiometers are the trim potentiometers . They do not have an axis for holding an operating button, but usually have a flat slot , or an adjusting screw . They are actuated ("adjusted") using a small screwdriver.

Some potentiometers, usually rotary potentiometers, have an additional switch integrated in their housing. This switch contact, which is then activated at one of the mechanical end positions, is often used to switch a device on and off, for example.

Multiple potentiometers combine two or more potentiometers in one component . A distinction is made here between a common, i.e. mechanically coupled actuation and a separate setting option with two buttons. Special forms of potentiometers are the so-called motor potentiometers . They can be operated both manually and via their mechanically coupled electric actuator. This also enables remote automation of actuating processes.

The electrical properties of potentiometers are defined by the type of resistance material and its linearity. The resistance materials can be a carbon or metal layer, and conductive plastics and composite materials made of ceramic and metal are also commonly used as resistance. The latter are also known as Cermet potentiometers. Wire potentiometers have a screw-shaped resistor wire wound around the (usually ceramic) insulating body, which enables higher electrical power losses than layer potentiometers.

A distinction is made between potentiometers with a linear resistance characteristic corresponding to the operating range and those with a logarithmic characteristic curve. Logarithmic potentiometers are required if a particularly wide setting range is to be implemented, for example for amplifier circuits for volume controls.

Trim potentiometers often require a particularly precise setting option in order to be able to carry out adjustments very precisely and to minimize operating deviations as much as possible. Multi-turn potentiometers are also available for this purpose, which allow up to 25 complete rotations instead of the usual 210° to 280° rotation angle.

Multi-standard versions are also available in different grades for rotary potentiometers. With up to 10 rotations, particularly precise settings are possible via the rotary knob.

Sliding potentiometers are always available when fast actuation is desired or the current setting position is to be detected quickly and clearly. Arranged next to each other, they also enable the simultaneous operation of several sliding potentiometers, which is common and necessary for mixing desks with their often numerous slide controls.