This circuit is from a 90s Popular Electronics. The transistors are of general use and the buzzer is a Sonalert type.
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...