Basic setup: The core circuit typically involves a neon bulb, a resistor, and a capacitor. The capacitor slowly charges through the resistor until it reaches the neon bulb's breakdown voltage. The flash: At that point, the neon bulb abruptly conducts, discharging the capacitor and glowing brightly. Recharge and repeat: The discharged capacitor then begins to charge again, and the cycle repeats, causing the neon bulb to flash on and off at a specific frequency.