bird imitator - exotic, perhaps, but not esoteric

exotic, perhaps, but not esoteric Perhaps it is a longing for nature in our technological society that prompts so many readers" requests for "electronic birds". And who are we to disappoint them? Since our knowledge of ornithology is rather restricted we would not like to say on which bird the present circuit is modelled, but it sounds exotic! The circuit consists of three relax- ation oscillators and a decade counter. The oscillators are astable multivibrators, AMV1 . . . 3, each of which is based on two inverters. Oscillator AMV1 operates at a fre- quency of a fraction of a hertz, which is used to clock counter IC2. As long as the counter is triggered, a logic 1 travels across outputs QO . . . Q9 in rhythm with the clock. Oscillator AMV2 may be compared with the throat of a bird: it generates an audible high-frequency tone. Oscillator AMV3 provides a range of frequencies with which the output of AMV2 is modulated, so that the final output sounds like a bird and not like the time...