Found in American documentation from the 1980s, this circuit makes use of components of the time, which are uncommon today. The circuit detects the approach using a sensor formed by metal plates.
This is the traditional configuration of na Astable Multivibrator using two NPN ttransistor....
This circuit, which combines a bipolar with any JFET, was found in the April 1993 issue of...
This filter was found in a Texas Instruments manual based on an operational amplifier 741. Other...