External Drive Transducers require a sine or square wave type signal at the appropriate frequency for the transducer. A sine-wave type signal will produce more sound level than a square-wave type signal. The higher the voltage level (up to the maximum allowed) the higher the sound level will be. Below are two circuits that can be used with external drive transducer devices:
It should be noted that the component values given are starting points only. For example, the inductor shown is optional and the value of the inductor will definitely have to be adjusted depending on the transducer used. Also, the oscillator portion of the transistor circuit will have to be adjusted to match the resonant frequency of the transducer.