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.
This circuit is from a 1967 publication. It is possible to power a fluorescent lamp from a 12 V...
This circuit was found in old American documentation. Transistor is general purpose and coil rated...
With a strong positive feedback (via a 10 M resistor) we can get the trigger setting for the...