This circuit operates from 25 to 65 kHz depending on the transducer used and the settings. We found it in the Radio Electronics magazine of July 1985. The 9V to 12V power supply is not given.
This circuit was found in the Linear Applications Handbook of the National Semiconductor of 1994....
This oscillator with the 4049 can generate signals up to about 14 MHz according to the article in the...
This circuit of a voice-controlled switch, Vox or sonic switch was obtained in a Popular...