Sound-activated-decoder


Posted on Aug 6, 2012

The piezo transducer operates as a sound-pickup device as well as a frequency-selective filter. By controlling the gain of the op amps, the oscillator can be transformed into a sensitive and frequency-selective tone-decoder circuit. With the gain of U1a set just below the point of self oscillation, the transducer becomes sensitive to acoustically coupled audio tones that occur at or near its resonant frequency. The circuit`s output can be used to activate optocouplers, drive relay circuits, or to control almost any de-operated circuit.


Sound-activated-decoder
Click here to download the full size of the above Circuit.

The de signal at the output of U1c varies with 0 to over 6 V, depending on the inputsignal level. One unusual application for the sound-activated decoder would be in extremely high-noise environments, where normal broadband microphone pickup would be useless. Because piezo transducers respond only to frequencies within a very narrow bandwidth, little if any of the noise would get through the transducer.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Led bar-graph driver
Class AB Power Amplifier Circuit 30w Using Power Transistor
Video IF circuit TV Schematic Diagram
an132
Build A Simple Twin Tee Phase Shift Audio Oscillator and Audio Amplifier
simple sound to light converter schematic
Solid-State Tesla Coil



Top