TikTok Explains What Those Extra Red Tipped Christmas Lights Actually Do

Holiday decorating can often be hectic. So hectic that amid the flurry of evergreen boughs, tinsel, garland, ribbon, and wrapping paper, you may not notice one very important addition to your Christmas lights that usually comes in a separate packet. Tucked amidst some extra bulbs, you'll find a tiny clear bulb with a red tip. While your first impulse may be to throw it away with other holiday packaging detritus or tuck the spare bulbs away in a junk drawer never to be seen again, you may want to hold onto those tiny red-tipped bulbs. Last Christmas, TikTok user @viznelly surprised many when she showed what those little bulbs are actually meant to do — they make non-flashing lights into flashing strands just by adding this single bulb.

While many commentators expressed their surprise at her discovery, the details are usually included somewhere in the directions for using the lights. Because Christmas lights are pretty easy to figure out how to use, and most of us have been dealing with them since our parents demanded we untangle lengths of them as kids, often these instructions, and the spare bulbs, wind up in the trash, ignored and unread. But these bulbs are a great thing to hang on to if you want a little more twinkle to your twinkle lights when decorating for Christmas.

While many LED light sets today have multiple controls for blinking and color changes, older and more simply designed sets rely on this single bulb, which contains a tiny extra piece of metal at the top called a bi-metallic strip. When this filament heats up due to the current, it bends, breaking the current and causing the lights that follow it to go out momentarily. As it cools, it bends back into place and relights. All the bulbs past this single bulb will blink in unison as they lose the current. 

If you decide to add the blinker bulb to your lights, keep in mind that only the bulbs on the strand past the red-tipped one will usually be affected, so place it nearer the power source to get all of them to blink or halfway if you want an equal number of static bulbs. If you can't find your stash of extra bulbs or inadvertently tossed them thinking they were just regular extras, you can buy small packs of red-tipped blinker bulbs from Amazon for a few dollars.