I often wonder how many of us equate the words "fun' with "engineering"? Like any job there is drudgery, but fun moments as well: initial design phase, laying out the basic building blocks of a product, that eureka moment. In lengthy discussions with the designer of our next generation of preamplifier, Bascom H. King, we decided to move away from the touch screen we so often use and move to a physical knob instead; just for the feel of it. There's nothing more satisfying than grabbing hold of a volume knob and feeling its precision steps as you glide up and down in level. Once decided, it's time to figure out how to make a physical control with just the right tactile feel and this is where the fun begins.
Using a knob for the volume has certain limitations; specifically the need to have a remote control, essential in today's equipment. Imagine turning the knob up and the display reads 62; now grab the remote and change that to 72, what happens to the knob? In some cases designers use actual potentiometers with motors connected to them and when the remote is pressed, the motor turns the knob and its control up and down, and everything's in synch. But, in this design we are not going to use a potentiometer because they do not sound that good and have issues with loss of resolution. Instead, we have a more elaborate scheme that loses almost nothing. To make this work one typically uses what's known as a rotary (optical) encoder, which is likely the same thing you have to control your car's radio; it spins in either direction forever. Though encoders work well, we decided not to use one because we could not control the feel of its movement; it might seem like that on your car, a little cheap. And here's where the fun comes in.
Our engineering people cleverly chose another type of rotary device instead, one that we could precisely control its tactile qualities. A very special motor was used in reverse to generate the specific pulses we need to know the position of the turn (a motor when turned acts like a generator). In normal operation it spins like any motor but only in steps, and not continuously, and we are using it in reverse. Stepper motors are common in industry but used rarely in consumer electronics. By applying a small and steady current to the motor we can control its user feel and make it silky smooth, yet with discrete steps. Building a prototype in the lab was fun and we all tested it out, commenting on the feel, adding just a little more or less current as if it were salt and pepper enhancing a good meal.
Yes the results of engineering can be fun for the user, but sometimes even more for the engineers.
