Found in a Hands-On Electronics from the 90s, this circuit produces the dial tones of an old telephone. The integrated circuit used is uncommon today.
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...