Posted on Feb 6, 2014

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 releasi

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ng 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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