While doing some cleaning through boxes of old components, I came across a ten-turn potentiometer from a previous life (see Photo 1). These pots were a common component of precision test and measurement units, as well as commonly the front panel of oscilloscopes to allow users to set precise time delays and trigger parameters.
Photo 1: A ten-turn pot such as this unit was a key element in a precision analog circuit or instrument; it has a smoothness in its rotational feel that matches its function.
As I turned the shaft, it rotated with just the right amount of smoothness and slight, consistent friction, with no jitter, and no axial radial play. This particular unit was from Bourns, rated at 1 kΩ, ±10% tolerance, and ±0.5 % linearity (it was very easy to determine those parameters, because they are written on its body). The ability to indicate these specifications simply by looking at the unit is one of its many virtues.
These pots were often coupled with a turns-counting dial (mine has gone “missing” -- Photo 2 shows is a typical one), which lets you know where you were in the multiturn rotation with precision and repeatability, and also allowed you to lock the shaft. Together, the ten-turn pot and counting dial were a potent and welcome addition to the precision T&M toolkit, and also inherently provided a nonvolatile way to store a user setting.
Photo 2: The ten-turn pot was usually used with a turns-counting dial, a combination that gave the user settability, repeatability, and a turn-locking mechanism.
While I was looking for the missing turns-counting dial, I also came across a small panel of basic toggle switches from previous project (see Photo 3), undoubtedly taken from some military equipment. I know it may seem weird to be lyrical about mere toggle switches, but these were the nicest I have ever used. Their feel and action are simultaneously easy and smooth, without feeling cheap. The switches have a subtle and satisfying clunk at either end of travel, which conveys with certainty but not harshness that the internal mechanism has seated properly. They provide a comforting, visceral feeling of assured performance, as strange as it sounds (and believe me, I know it does sound somewhat strange).
Photo 3: These "simple" toggle switches provide a basic on/off function with a satisfying feel and sound in their click-over action.
You don’t see many of these components anymore, for many reasons. They are fairly costly, large (both in front of and behind the panel), inflexible, single-purpose, and non-reconfigurable. Reality is that they are simply not needed in many of today’s designs, where a pushbutton and software can replace or emulate their function, and also do so much more.
Do I miss these components? I have mixed feelings, to be honest. On one side, they provided certainty in use, a sort of “WYSIWYG” of settings and stability, with no worries about volatility, power loss, software bugs, and other misfortunes. On the other hand, we had to abandon them and go to software-based functions, soft buttons, and touchscreens, often with menu-based dynamic reconfiguration of the switch functions, to get the designs we now want and can realize.
Are there some analog components -- switches, pots, or others -- that conjure up memories of days past? Are there any that you miss, or also some to which you are truly happy to say goodbye?