The 555 Timer in this circuit uses an incandescent lamp rather than R-C (or L-C) timing circuits. It works off the principle that the resistance of an incandescent lamp filament increases as it self-heats. This process has its own thermal time constant, and long ago, I built and tested a circuit that allowed a 555 timer to monitor the changes to filament resistance when the lamp turns on or off. The 555 Timer IC does not seem to mind, and happily blinks away at about 1 Hz. My circuit notes are shown. Have fun experimenting.