This circuit was obtained from an 80's EDN. The components used are still common. The circuit can be used as a shield and the frequency is approximately 775 Hz.
Indicated for scanning circuit applications, we found this generator in a Radio Electronics from the 80s....
This circuit tests crystals up to a few megahertz with ease. The circuit is from a 1977...
Found in documentation from the 70s, this circuit uses an operational one from that time. It goes for...