SOUND_EFFECTS_GENERATOR_1

Published:2009/7/6 6:03:00 Author:May | From:SeekIC

This circuit can generate a European police-car slren,bird nolses,spaceship sounds,etc.In addition,it can be put to use as a doorbell,an alarrm,etc.The circuit consists of four parts:a binary counter,a D/A converter,a VCO,and an audio output amplifier.The initial frequency of oscillation IS determined by potentiometer R11.The VCO firstoscillates at a relatively low frequency,and gradually picks up speed as the control voltage supplied by the D/A converter mcreases.The D/A converter IS the group of resistorsR1-R8.When none of IC1's outputs IS active,little current will flow into the base of Q1,so the VCO's control voltage will be low.As more and more counter outputs becomeactive,base current mcreases,and thereby so does the VCO's frequency of oscillation.The VCO itself IS composed of IC2-a,IC2-b,Q1,and the timing network comprising D1-D4,C1,R10,and R11.The buffer amplifier is made up of the four remammg gatesfrom IC2,all wired In parallel.



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