Bests & Worsts Reviews from Amazon

Okay, admit it: you read the package, mix in even a basic understanding of electricity, and wonder why anyone would fall for such an outlandish claim. Surely, you can't fix a lightbulb by passing more electricity through it, no matter the "shape" of the pulse! This DOES work, though, and it's because Christmas light bulbs have long been designed to work this way. Every bulb in the light set you own has a "shunt" which is supposed to "melt through" when the filament burns out. And, fairly often, it works just fine. However, every once in a while the shunt doesn't melt through given the "normal" voltage difference across the bulb, and so the circuit (for the 50 lights in that set or portion of the set) is lost. That's when not just one lgith goes out (which you might often not even notice), but the entire section of lights turns off. That's where the "pulse" fixes things. It provides a low-current, high-voltage difference across the bulbs, which is sufficient to melt the shunts in any burnt-out bulb while not affecting functioning bulbs. Then, you scan for the bulb (or two) which is/are still burnt out, and replace just those. Those are the ones which have been burnt out from the start, but at least one of whose shunts had not melted through. Now, that said, where can this process, and thus product, fail? For one, if there are a huge number of burnt-out bulbs in your chain and they ALL failed to melt through their filaments, it is likely that the device won't be able to work through them. Further, if you have a *loose* bulb in the set, this will do nothing at all for you. You'll need to use the current detector (also a part of this device) to scan along the wire to see where continuity is lost, and replace that bulb or try just reseating it. Depending on the quality of your light set (and they all are trending towards identical quality) this might be the result of a slightly "loose" socket, a bulb improperly put in at the factory, or, maybe, a bulb you replaced improperly previously. In storage or in transit, bulbs undergo some stress which can twist or pull on them, transforming a "good enough" bulb-socket connection to a not-gonna-work kind. Long story short: bulbs get unseated, and you'll need the circuit proximity detector in that case, which is a much more involved process than just plugging in and hitting a button.