Most ultrasonic transducers can be operated at input levels up to 50 ... 80 V peak-to-peak. This usually means employing an ultra-sonic oscillator followed by an amplifier (with a 50 ... 80 V supply) to drive the transducer. Provision of this amplifier and its high voltage supply inevitably complicates the system, since other parts of the alarm system will probably be operated from a lower voltage (e.g. 12 . . . 15 V). The alternative is to operate the transducer at the same low voltage level, with a consequent reduction in range.
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