Using two unijunction transistors, this circuit found in Electronics World generates linear sawtooth signals. The frequency depends on the capacitors being around 500 Hz.
With 3 transistors, we found this receiver in a documentation from 1966. The circuit has an output...
This circuit was found in the December 1977 issue of Radio Electronics magazine. The circuit uses...
This circuit was published in an English magazine from 1981, but it can be easily assembled today,...