Found in a 1964 Electronic Design, this circuit generates pulses based on an avalanche diode of the time. The circuit can be tested with modern equivalent components.
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...