This analog frequency meter for low frequencies was found in Radio Electronics magazine from July 1958. The circuit has several scales with the frequencies indicated in the diagram.
This very old circuit, from a publication from the 1970s, uses a germanium transistor and two...
In the figure we have a very sensitive touch switch circuit. A touch of the sensor causes the...
In fact, we can say that this circuit found in documentation from the 90s, consists of an intercom...