Problems associated with driving an efficient Tonpilz transducer with broadband signals

• Published in: The Journal of the Acoustical Society of America 1999-10, Vol.106 (4_Supplement), p.2258-2258
• Main Author: Lubell, Alan H.
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.427699

A symmetrical piezoceramic-stack-driven Tonpilz makes a very efficient underwater loudspeaker for use in any body of water where human activity takes place. The large variation of impedance with frequency makes driving this type of transducer a unique problem. Transformer leakage inductance together with stack capacitance causes excessive current to be drawn at the series resonant frequency, which must be controlled with an appropriately sized series resistor. This paper presents measured and computed frequency responses and impedance magnitude versus frequency graphs for several of Lubell Labs.’ underwater acoustic transducers. Included are recent calibrations made at the USN Dodge Pond facility. These are used to determine suitable values of leakage inductance and series resistance. A reasonable size series resistance is one that will not cause excessive loss at the fundamental transducer resonance. Excessive leakage inductance must be avoided because of its effect on high frequency response. An expression for the current drawn when the transducer is driven with bandlimited pink noise has been derived by the author and will be given herein.