Uses 5558 dual opamp and four general-purpose NPN transistors to generate triangle wave that can be distorted by 10k symmetry control to give either fast or slow rise for sawtooth applied as base bias to astable MVBR Q1-Q2. Drain is reasonably low with 9-V radio battery, Repetition rate can be varied from long wail to rapid warble, and volume changed from soft to annoying.
LOUD BIKE SIREN - schematic

Article gives construction details, and recommends use of removable mounting on bike to avoid theft.-R. Megirian, Simple Electronic Siren, 73 Magazine, Oct.1977.p176-177.

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