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

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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