We found this circuit in the July 1988 Radio Electronics magazine. The frequencies are given by capacitor C1 and the voltage input is made at pin 1.
This circuit is from an old American publication, using transistors of the time and operating with a 48...
September 2016 - It can be obtained from Mouser Electronics the new ADC AD7779 from Analog Devices with...
Found in a QST magazine from the 90s, this circuit broadcasts on different amateur radio bands...