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Fourmilab's Coruscating, Actinic, (partially) Nuclear-Powered Christmas Lights
'Tis the season to put up the Christmas lights and, as usual, confront the problem of dead series-strings of incandescent bulbs. Now, if you're an engineer like me, you've probably developed a pretty strong sense over the years about how the world works. This hindbrain reality detector will probably rule out ever finding a string of 12 bulbs in series in which three or four have burned out filaments, but in fact this is common when repairing such lights. What's going on? I'm not entirely sure—the most plausible explanation seems to be that when a filament opens, you can often get the string working again by tapping it against a window (or other hard object). This will sometime jog an open filament back into contact, so the string lights again until another filament opens, which can sometimes be remedied in the same way. When the thing resolutely refuses to light and you take it to the bench to repair, you find multiple dead bulbs, many with obvious open filaments when viewed through a 10× magnifier. On the other hand, the explanation may be tiny filament snipping gremlins from the fourth dimension who materialise inside the bulbs when the lights are stored in the attic waiting for next year. But this engineer is not going there. Regardless of the cause, it is intensely irritating when one of these strings of lights fails. Each one contains 12 “grain of wheat” bulbs, driven with 24 Volts AC
'Tis the season to put up the Christmas lights and, as usual, confront the problem of dead series-strings of incandescent bulbs. Now, if you're an engineer like me, you've probably developed a pretty strong sense over the years about how the world works. This hindbrain reality detector will probably rule out ever finding a string of 12 bulbs in series in which three or four have burned out filaments, but in fact this is common when repairing such lights. What's going on? I'm not entirely sure—the most plausible explanation seems to be that when a filament opens, you can often get the string working again by tapping it against a window (or other hard object). This will sometime jog an open filament back into contact, so the string lights again until another filament opens, which can sometimes be remedied in the same way. When the thing resolutely refuses to light and you take it to the bench to repair, you find multiple dead bulbs, many with obvious open filaments when viewed through a 10× magnifier. On the other hand, the explanation may be tiny filament snipping gremlins from the fourth dimension who materialise inside the bulbs when the lights are stored in the attic waiting for next year. But this engineer is not going there. Regardless of the cause, it is intensely irritating when one of these strings of lights fails. Each one contains 12 “grain of wheat” bulbs, driven with 24 Volts AC
Issue #2
Excessive icon, could be removed
- Type of issue
- Rudimentary content not removed
- Reported
- Mar 10, 2019