This circuit was found in the October 1983 Radio Electronics issue. It is applicable to old analog telephones. The circuit uses common components.
This circuit was found in the February 1981 issue of Radio Electronics magazine. The circuit uses...
Found in American documentation from the 90's, this circuit oscillates up to 150 MHz. The...
This circuit can work with power voltages from 6 to 35 V, being suggested by the Motorola Linear...