This circuit was found in a Popular Electronics from the 90's. It triggers an audible warning at the end of the time programmed by the R6 setting. Capacitor C2 can be extended for longer time intervals.
This circuit was found in a Popular Electronics from the 90's. It triggers an audible warning at the end of the time programmed by the R6 setting. Capacitor C2 can be extended for longer time intervals.