What’s with pots?

What’s with pots?

Potentiometers, it seems, are kind of like the cockroaches of the component world. They’ve been around for quite a long time and have stayed pretty steadfast through all sorts of advances in technology.

Or have they?

Well, what exactly is a potentiometer? Trusty ol’ Wikipedia defines it as “a three-terminal resistor with a sliding contact that forms an adjustable voltage divider.”

From there, things get a bit tricky.

Despite being related to resistors, since their invention back in 1841, potentiometers or pots — have evolved into a slew of different configurations and types, and are used in a wide variety of consumer and industrial applications including test equipment, audio, medical, and robotics.

Besides being used for measurement or adjustment, pots also have a tendency to mimic other components. They can be trimmers or they are frequently confused with closely related rheostats. Both are variable resistors and both translate mechanical input to an electrical output. Pots can even be sensors, which seems to be an increasingly preferred use for them today. The thin line between potentiometers and position sensors is more closely examined in a recent article in Electronic Products (http://tinyurl.com/4jnrh4e).

While these versatile “traditional” pots have survived into the digital era, digital potentiometers, or dig-pots, have also been developed, which can certainly replace their mechanical counterparts in certain applications.

Most recently, pots have been configured using a conductive membrane that is deformed by a sliding element to contact a resistor voltage divider. Some manufacturers are now offering thin-membrane linear and rotary potentiometers for applications that require position adjustment or position sensing.

But, recent innovations are almost nonexistent. Potentiometers have played a key role in many human interface devices, which we will always need. But what form will they take, and will variable resistors be one of them? Telephones have gone from dials to pushbuttons to touchscreens and voice commands. Keyboards and touchscreens are edging out pens and pencils. Will knobs and sliders still be relevant in the future? It seems that potentiometers may not take center stage like they used to.

So, what’s with pots these days?

Will you still be using them in your designs 10 years from now?

cdairo@hearst.com