The Standard Open (S) Type Transducers consist of a piezo-ceramic disc bender mounted at the node of its fundamental resonant frequency, a quarter wavelength conical metal resonator bonded in the centre of the disc, acting as a rigid piston movement. This special construction provides high sensitivity and sound pressure level, wider bandwidth, excellent temperature and humidity durability and stable electrical and mechanical characteristics. The S type transducers are suitable for continual driving circuits, such as Doppler motion detectors. For application of echo ranging (pulse driving) please refer to the following pages of Pulse Transit (PT) and Enclosed Pulse Transit (EP) type transducers.

The Standard Enclosed (E) Type Transducers can be used for outdoor installation, or, because of its special dust-proof construction, can be used in a dusty atmosphere. The transducers consist of a metal housing with integral diaphragm, which operates at resonance on the first harmonic overtone. The backs of the transducers are completely sealed with resin, protecting from exposure to the environment. Although they are of a watertight construction, it is not recommended that they be used underwater. Due to its free vibration and un-damping characteristics, the (E) type transducers are suitable for continual drive circuits, such as Doppler motion detectors.