This circuit was found in the May 1982 issue of Radio Electronics magazine. The circuit inverts the polarity of a power supply to obtain a voltage of -5 V.
For those who like experimental circuits, here is a sequential flasher system with LEDs, which can be...
This circuit was found in an ancient American documentation. The integrated circuit is of the time...
This circuit was found in a 1977 Radio Shack documentation. The circuit is tuned to 1.4 kHz, but...