This circuit is from a Radio Electronics magazine from August 1990. The circuit uses components from the time and is suitable for measurements in alternating current.
This circuit is from an English magazine of 1977. The circuit is still current, just using BC547...
This circuit was obtained in an old Elektor. It is a reference, since the integrated products of the...
This circuit was found in a European technical documentation from 1991. It is a circuit that must...