Found in American documentation from the 1990s, this circuit generates a whistling sound when applied to an amplifier. The power supply must be symmetrical.
Found in a 90s Popular Electronics, this circuit is interspersed between the filter and the...
This circuit is from an 80's documentation. The integrated circuit is from the time and the...
This circuit was found in a 80s American documentation. The zener diodes determine the points of...