LightKeeper Pro

By on December 12, 2005

I stopped at Ace Hardware this afternoon, and ran across a gadget I’d never heard of before; the LightKeeper Pro. This is the thing if you’ve ever fought with a string of miniature Christmas lights that wouldn’t work — it fixes them.

The LightKeeper Pro is designed to solve the frequent problems associated with Miniature Light Sets and Bulbs.

By simply plugging your light set into the LightKeeper Pro and pressing the Trigger, most problems can be fixed automatically.

Most miniature Holiday Light set failures occur when an individual bulb “shunt” fails to energize. These shunts are energized when a filament burns out. This causes a section of lights, usually 35 or 50, to go out instead of just one light bulb. This is because miniature light sets are wired in “series” and electricity must flow through each bulb, to the next, for them to light.The LightKeeper Pro Quick Fix Trigger sends a shaped, electrical pulse through the defective bulb, clearing the shunt. This allows it to operate properly. The current can then flow through the light set completing the circuit and illuminating the other bulbs.

I don’t pretend to understand how you can “shape” an electrical pulse, but if the demo video is to be believed, it seems to do the trick. Any EE’s out there want to take a stab at explaining the science behind this thing?

I threw out two strings of lights a few weeks ago because I couldn’t get them to work. But I’d have to go through several $3 light sets to justify the $20 they wanted for the LightKeeper Pro. Maybe I’ll just wait until after Christmas, when they are sure to go on clearance.

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  1. You can make an electrical pulse with (almost) any shape that you want. EE101 generally starts with pulses and combinations thereof. That’s one of the reasons that EE texts are inaccessible to people who actually know something about electronics. It is entirely possible to obtain an BSEE without knowing anything about electronics. But I digress.

    Here, I’m guessing that the device generates a pulse with a relatively high voltage but a very limited current, sorta like a large battery in series with a high resistance. When the lamps are connected in series with the resistance, no current flows and all of the battery voltage appears across the filament of the open lamp. This high voltage (presumably) burns the resistive material off the bulb shunt and allows it to work. Once the shunt is activated and current starts to flow, most of the voltage appears across the high resistance and very little voltage appears across the shunt, thereby not burning it out. You can see a better way to do this with ICs, but the principle is the same.

    If you want more info on the bulbs, page 3 of has a pretty good explanation.

  2. hmm, sounds like a tool solely for the people who feel it necessary to cover their entire house in Christmas lights. The purpose of such an exercise eludes me.

    btw, thanks for the explanation Brenda, very comprehensive.

  3. sounds like a tool solely for the people who feel it necessary to cover their entire house in Christmas lights.

    Not necessarily; I just hate throwing out a string of lights because of one stubborn bulb that doesn’t do what it’s supposed to do. I was talking with someone this morning about this thing, and she brought up the fact that although it may be cheaper to replace the lights than to buy & use a LightKeeper Pro to fix the string, what about a string of lights that’s already strung up in your Christmas tree? If fixing a bad shunt keeps me from having to unstring and restring, I’m time ahead.

    But there are some, like this guy, who definitely need one.

  4. Thanks! It was fun to finally be able to contribute something to a site that I visit every day and that I enjoy a lot.

  5. I have used this tool about 10 times this year and it worked 9 times. One application noone mentioend was on a pre-lit tree! Try popping 100 or so bulbs out from around the tree and next to the trunk. I used this to fixa bad shunt in 3 minutes and then replaced the bad bulb. It is also very handy if you lights up outside and a grid burns out (i.e. in net lights). You don’t even have to take them down to fix them. I got mine after Christmas for $10. It is definitely worth even $20.

  6. It is amazing! After spending >$7 for icicle strings (and to do my roofline requires ~14 strings) a few years ago it has been extra frustrating each year to be throwing out icicle strings!

    This has solved the problem and it works very well. I’m more of a 4 out of 5 times working situation but nonetheless it is an amazing tool and has easily saved me the $ of a new string and enormous frustration with bulb in bulb out stuff!

    Great tool!

  7. I love this tool. I can’t tell you how many times I have used it and how many strands I have NOT thrown away because of this $20 tool. It is also convenient to test the fuses with it. I went back and bought extra tools to give away as Christmas gifts.

  8. Are you kidding me, rather keep buying new strings at 3 bucks each. Oh yes , I would much rather keep driving to the store and wasting time and gas. Wow 20 dollars !! I bought this this thing and fixed some lawn fixtures that havent worked in years!!! It fixed every single string I tried it on. Only one note, I will say sometimes you have to try it in a couple diffrent sockets before some strings will light up. Great Great Great product.

    PS. Most good light strings are about 8 bucks for just a 100 lights.

  9. Sounds great. I have one. It beeps every possible location indicating all light should work. Bull. One whole group of six branches refuse to light up. Re read and re checked every string, every bulb. Still no light. Wrote email to the great light keeper web asking for help. No response. Just proves one cannot believe all the crap as advertised.

  10. For what its worth, I love this thing. I have a large pre-lit tree and this year it had 5 or 6 sections of lights that did not light when I set it up. I pulled one bulb out and pulled the trigger on the tool 2 times and every section that was out lit up. It saved me hours of pulling lights trying to find the problem bulbs. Two minutes of my time and $18 and I am back to decorating the tree instead of being ticked off and putting new lights on a large tree. It paid for itself with two pulls of the trigger!

  11. My husband thought this was the greatest thing since sliced bread for about 45 minutes. Then he found a string of lights that needed a little fine tuning. He “fixed” the string, was in the process of hanging them on the house and they went out. Try as he might, half of the string WILL NOT COME ON. He trouble-shot everything in the instructions and finally bought new lights. How does the beeper signal keep beeping when all the lights stay out?

  12. This ia a great well made well thought out product. My unlit reindeer of five years has burst into life. Well worth the price to avoid light hassle

  13. One thing to consider if your light pro isn’t working is that it runs on 3 batteries. Mine where dead and I replaced them with a cross referenced battery from walmart LR44 and I am back in business. It’s a nice tool to share with friends and family.

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