Figure 18 is a useable schematic. A LM386 audio amplifier output is connected to a mini-stepup transformer. The output of the mini step-up transformer activates the piezo-film speaker.


Piezo Electric Film
Figure 18

Experiment with the piezo speaker by gently curving the material, see what radius gives the best frequency response or sound volume. You may attache the speaker to an air filled balloon. There were plans to market helium filled balloons made from this piezo material to create balloon speakers.


Bimorphs

Motion can be created using piezoelectric film. To do so, two sheets of film are joined together. This assembly is called a bimorph. The sheets are arranged so that when a voltage is applied to the bimorph, one film laminate lengthens while the other contracts. This caused the bimorph to bend. Applying voltage of the opposite polarity will cause the bimorph to bend in the other direction.


An AC voltage will cause the bimorph to fan like an insect wing. At resonance, maximum movement will be obtained from the bimorph. Resonance is determined by the length and thickness of the piezo materials used in the construction of the bimorph.


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