Using a 555, this configuration appears elsewhere on this site. This is from American documentation from the 90s. The indicator can be an LED or some device controlled by a relay.
Activating a relay from pulses (from a monostable, for example) can be useful in many types of...
August 2016 –It can be purchased from Mouser Electronics the new converters BD7F100 and BD7F200...
This circuit that appears in other points of this section and on this website serves to activate a...