This circuit is from a 90s Popular Electronics. The transistors are of general use and the buzzer is a Sonalert type.
We found this circuit in an American 1980s documentation. Transistors may be general purpose...
This oscillator version is from an RCA documentation from the 1970s. Transistors support modern...
We found this circuit in a publication by General Electric in the 1980s. The transistors and the...