This circuit is from a documentation from the 70s. The circuit uses logic gates of the time, which in many cases were arrays of transistors allowing use as audio amplifiers, as in this case.
This circuit generates pulses at a frequency that can be adjusted by a potentiometer. The circuit is...
This oscillator uses a small IF transformer taken from an old transistor radio. FET admits...
Found in a 1970 EEE, this circuit generates signals that depend on the C1 capacitor. Transistors are...