We found this battery eliminator in a Radio Electronics magazine from August 1974. The transistor must be equipped with a heatsink and other voltages can be achieved by replacing the zener.
This circuit was obtained in a documentation of the 80s, using operational of the time. The...
In the figure we have a third fast adder that we found in an 80's Electronic Engineering. The circuit can...
We found this simple music box circuit that can also be used in a musical bell in a 1991...