This circuit was obtained from the March 1994 Electronics Now magazine. The circuit uses a common transistor which can be a low noise type such as the BC549.
This circuit was found in an 80's American documentation, serving only as a reference and not for...
Oscillators up to some megaherts can be made with comparators like the LM139, 239 or 339. Theses...
We found this circuit in the July 1988 Radio Electronics magazine. The frequencies are given by...