Different Types of Variable Power Resistors

A variable power resistor is a power resistor that offers adjustable or varying electric resistance values. It is specifically an electro-mechanical transducer that typically functions by sliding a contact (wiper) over a resistive item.

Here are the three types of variable power resistors:

Potentiometer

A potentiometer is a basic type of variable resistor that works as a potential divider, whose role is to trigger a voltage signal, depending on where the potentiometer is positioned. This type of signal is used for an entire range of applications, from amplifier gain control to circuit tuning and more. Each time variable resistors are used for calibrating or tuning a circuit or its application, trimmer potentiometers or trimpots are used. These are generally less rated potentiometers that are installed on the circuit board and can be tweaked with any screwdriver.

Rheostat

Rheostats are more similar to potentiometers in construction than in function. They usually come in handy as variable resistors where only 2 terminals can be used, as opposed to 3 terminals with a potentiometer. A connection is set up at one end of the resistive element, and another one at the variable resistor's wiper. Back in history, rheostats worked as power controllers and, as in a light bulb, were connected with the load in series. Today, rheostats are no longer used for controlling power as has been found to be inefficient. Variable resistors are also now wired like the rheostats, which are useful in calibrating or tuning circuits.

Digital Resistor

A digital variable power resistor such as from this wirewound resistors company is a type used when electronic signals are behind resistance changes instead of mechanical movements. They can change resistance in subtle ways and are often under the control of digital protocols like I2C or basic up and down signals.

Presets

Finally, presets are like tiny variable resistors that can be readily placed on a PCB and adjusted as necessary. The resistance value is usually tweaked using a screwdriver. They are common in applications with variable alarm frequency tones or sensitivity circuits. These are also the most cost-effective among all the devices mentioned previously. In addition, they are highly specific presets with multiple turn options. In such preset types, the resistances are slowly driven up or down and hence the screw must be rotated with more repetitions.

Because of their versatility, variable resistors have so many practical uses, such as for audio control
television, transducers, home electrical appliances and many more. Judging by how they're called, it's easy to see that they are, in fact, the most widely used power resistors. Click here to find current sense resistors.