0xFF

It described how neon lamps can be used as logic elements in a ring counter, exploiting the fact that they need a higher voltage to ignite (the striking voltage) than to stay lit (the maintaining voltage): Unfortunately, if one substitutes the neon bulbs that are available in electronics shops nowadays, the circuit doesn't work. Dance used lamps that were specifically manufactured for this type of application, with a large difference between their striking and maintaining voltages. Nowadays, such lamps are (presumably) no longer manufactured; the neon bulbs that are still available in shops are meant as indicator lamps, and have a much smaller difference between their striking and maintaining voltages. This required changing the circuit's resistor values, and makes its operation more critical; furthermore, the lamps need to be selected for matching characteristics.