We found this circuit in the 1977 RCA Solid State ICs. The circuit consists of a current amplifier with a gain of 1000. The supply must be made from a symmetrical source.
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...