This circuit is from a 90s Popular Electronics. It consists of a power source for bass amplifiers of common types at the time that used symmetrical power and separating filters.
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...