Ward & Goldstone Limited

John Parkes

Michael J Hampshire

Norman J Poole

An open ended can has a piezoelectric crystal attached to its closed end face and contains within it the battery supply and circuitry operative to cause the can to resonate. The can is attached at its open end to a back board through a ring of closed cell foamed synthetic plastics material to form a waterproof enclosure for battery and circuitry. The circuitry is based on one or more CMOS integrated circuits having gates or inverters connected to form one or more oscillators and one of the oscillator pulses the crystal through a transistor power amplifier and step up transformer. That oscillator may be adjusted off the resonant frequency to reduce the output or a feedback path provided to lock the oscillator onto a resonant frequency.

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Manchester, United Kingdom

John Parkes