ADJUSTABLE_SIREN

Published:2009/7/22 1:06:00 Author:Jessie | From:SeekIC

Tone is made adjustable by using multiposition switch to change capacitors in oscillator circuit. Speed (rate of change in frequency) of siren is adjusted with R3. 4700-ohm resistor in series with R3 keeps siren op-erational when R3 is rotated to minimum-resistance position. Siren is operated by pressing switch to produce rising wail, then releasing switch until wail drops down to cutoff.-F. M. Mims, Transistor Projects, Vol.1, Radio Shack, Fort Worth, TX, 1977, 2nd Ed., p 58-63.



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