This high voltage circuit was found in a 1970 documentation. The integrated one is of the time and modern equivalents can be tested. The resistors of the voltage reducing system must be calculated.
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...