how to make heallight/tail flasher

i would like to know what i could use to CONTROL this system. i realize that the best way to have it work without feeding back is to isolate each bulb in the setup so that when the relays are powered to flash the light switch is being protected from damage.

i want to control it as if it were like police flashers.....not the strobe lights, but the actual headlights and tail lights. would it be better to us relays to activate the highbeams and relays to activate the brake lights aside from the 3rd mini light?

what to use to trigger? it has to be something that triggers the relays twice every 2 seconds....or less.

any ideas?

thanks for the response, i think that is what i'm looking for, i drew it out to make sense of the diagram....i think it will work, too bad it didn't show a better shot of the controller. says it will only handle circuits up to 10amps, that means that it shold be a pretty basic potentiometer.....i would think. because the work is done soly by the relays all the controller is doing is controlling the speed of the ground pulse to the relays itself.

awesome. thanks!