We found this circuit in documentation from the 90s. The circuit uses components that are still common today, turning off a load after the programmed time. The time is given by the capacitor.
This oscillator was found in the November 1986 issue of Radio Electronics magazine. The frequency...
This sophisticated circuit with a low, medium, and high treble filter is from 1990 documentation. The...
This circuit was obtained from a 1998s Popular Electronics. The magazine no longer exists, but the...