This circuit was found in ancient American documentation. It makes use of the operational amplifiers of the time, but it can be implemented with modern equivalents.
This 1995 circuit uses interruption sensors or NC connected in series in any quantity. With the...
The integrated circuit used in this amplifier is not common today. The circuit is from a...
This circuit turns off a load after an interval of 8 to 80 seconds adjusted on the potentiometer. The...