This simple source with zener regulation is ideal for experimental projects with operational amplifiers. Other voltages can be obtained by changing the zeners and the transformer.
Based on 4066 CMOS, we found this circuit in a Popular Electronics from 1992. The signal is...
This receiver of two transistors for the 3.5 MHz band was found in a circuit manual from the 80's....
This circuit uses an unusual Motorola integrated. The circuit is from Motorola's 1990 Linear...