This circuit was obtained in a Popular Electronics of the 90s. The circuit uses integrated from the time, uncommon today. Note that the speaker has a higher impedance than ordinary speakers.
The output voltage of this unit is approximately 1.4 V less than that of the chosen zener. The...
Found in the April 1980 issue of Radio Electronics magazine, this stage uses transistors from the...
To control direct current loads, under voltages between 12 and 200 V, and currents up to 3 A, we...