Abstract: An ultrasonic distance measurement system for use in air is presented. The measurement is based upon the two-frequency continuous-wave (TFCW) phase-shift method. In the system, two vernier ...

A vernier dial for radio tuning. Circular plastic plate with molded grip, molded scale 0 to 100 by tens, center mounted control knob operating a brass gear meshed with an internal gear plate.

A plastic housing with graduated scale seem through three ports. Knob on front actuates scale. Brass acorn nut at center holds the unit together. Knob rotates a brass post that turns a brass plate, ...

On the whole, the bell's design has remained largely the same for the last century or so.The need for cyclists to alert other ...