The sound produced by this circuit, from a 1978 publication, depends on the humidity between the electrodes. In contact with rainwater harvested in a container, the circuit begins to oscillate. The critical components are the transformers that can be obtained from old transistor radios. The transistors can be the BC558 and the power can be made with voltages from 6 to 9 V. Do not use a transformerless power source.
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