This traditional signal injector configuration was obtained in a 1977 amateur radio manual. The frequency is given by the capacitors and the supply can be made with 1.5 or 3 V.
Using the 709 integrated circuit, one of the first operational, this circuit was found in the...
The circuit presented generates pulses at regular intervals with the duration controlled by a...
Found in a 1966 documentation, this circuit monitors the operation of an air conditioning system....