Found in the March 1989 issue of Radio Electronics magazine, this circuit is used to test printer and other cables. The indication is made by LEDs.
We found this circuit in the 1960 Mullard transistor reference manual. The phototransistor can be a...
This simple circuit was found in an old documentation. The transistor can be changed according to the...
This circuit was found in an 80's Electronic Engineering. The power supply must be symmetrical. The...