This circuit is from American documentation from the 70s. This configuration appears in this section obtained from other sources. The signal is sinusoidal determined in amplitude by D1 and D2.
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...
This circuit can act as a shield being controlled by a microcontroller by pin 1 or 2. The...
This circuit was obtained from a 1980's QST magazine. The circuit can generate 1 to 15 MHz signals...