Found in a 90’s Radio Electronics, this circuit uses a component from the time, difficult to find today. It generates 12 tones in different octaves.
This circuit is from a 1995 publication. The components are all common and the number of LEDs may...
This circuit, found in a 1995 documentation, is intended for switching composite RGB video signals...
This circuit is from Motorola's Linear Interface ICs of 1993. The integrated circuit is not common...