The circuit below is suggested by National Semiconductor in technical documentation on the LM3909. The circuit is powered by a single battery and has a very low consumption.
This circuit interrupts the power supply when grounding is missing. The circuit is from an old...
We found this circuit in an old American documentation. The circuit applies to modern equivalent...
The trigger shown in the figure, built around a 4093 can generate pulses that reach 1 hour with a...