This project inspired by relay pulse keyer from Nyle Stelner. In my case, i don't have 2-pole, 12 volts relay, so replace this with two 5 volts relays because are more common to find.
I use this circuit for make experiments with some radio transmitters from factory or homemade. Also it could be used to turn on/off any device that you need such as: fountains, lamps, lights, fans, etc.
The circuit on and off the relay contact once every second.
Although there are solid state designs, I have made this design because I like to hear the click click of the relay working, and on the other hand the circuit will work even if we suffer a EMP electromagnetic pulse (Preppers will love it :-D) .
Next the circuit, pictures and video of operation:
Schematic
Inside
The relay pulse keyer into Altoids tin