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.
The oscillator in figure 1 can be used in alarm, call or warning systems, producing a sound of...
This circuit is from a 1973 documentation. In it we have the way of using a FET as an input of...
This circuit is for traditional old-style telephone lines found in an American 1980s...