This circuit can be used in a signal level indicator with LEDs. The circuit is from an Electronics Now dated January 1996. The power supply must be dual.
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...