Found in Texas Instruments documentation from the 1980s, this circuit applies to digital signal transmission with FSK modulation. The circuit is slow, as it uses period components.
This circuit is from an Electronics World of 1968. The transistors are of the time and the power...
The circuit shown here produces a pure square tone of 440 Hz that is suitable for musical...
This powerful amplifier with output in complementary symmetry is from an old documentation....