AUDIO_NOISE_GENERATOR

Published:2009/6/26 2:10:00 Author:May | From:SeekIC

This simple circuit generates both white and pin noise. Transistor Q1 is used as a zener diode. The normal base-emitter junction is reverse-biased and goes into zener breakdown at about 7 to 8 volts. The zener noise current from Q1 floirs into the base of Q2 such that an output of about 150 millivolts of white noise is available. To convert the white noise to pink, a filter is required which provides a 3 dB cut per octave as the frequency increases.Since such a filter attenuates the noise considerably an amplifier is used to restore the output level. Transistor Q3 is this amplifier and the pink noise filter is connected as a feedback network. between collector and base in order to obtain the required characteristic by controlling the gain-yersus-fre quency of the transistor. The output of transistor Q3 is thus the pink noise required and is fed to the relevant output socket.



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