DIGITAL_NOISEMAKER

Published:2009/7/7 3:25:00 Author:May | From:SeekIC

Simple sound-effect generator for video games, electronic cash registers, and electronic toys uses one-fourth of LM3900 quad opamp chip as 2-kHz signal generator that can be turned on or off by input control voltage. Suitable for applications that do not require pure sine wave. Output transistor O1, needed with low-impedance voice coil, is not critical as to type. For smaller acoustic output, Q1 can be replaced by 100-ohm resistor if 100-ohm voice coil is used, to avoid overloading IC.-T. Frederiksen, Build a Transformerless Tone Annunciator, EDN Magazine, April 5, 1977, p141-142.



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