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.
This is a complete version of the previous circuit, with several scales and two transistors, one...
This sensitive circuit produces na outpu signal when a body is detected by the sensor. The circuit...
Found in a 1966 American publication, this circuit invert the phase of a low frequency signal. The...