In the original publication of the 90s a 556 consisting of a double 555 is suggested. The circuit drives a speaker with good power. The power transistor shall be fitted with a heat sink.
April 2017 - Mouser Electronics already has the MAX4007 from Maxim Integrated in its inventory, an...
This circuit was obtained from an English magazine from 1979, but can be easily assembled today...
Found in a 1978 publication, this circuit uses germanium transistors and drives a small 20 to 50...