How the LED Keeper Works

[Spork Schivago]

I'm watching this video on something called the LED Keeper: https://www.ledkeeper.com/4-minute-d...ration-videos/

At around minute mark 1:24, they show how the LED Keeper can power an unlit section of a string, once a bad bulb is found.

You plug the string into the LED keeper instead of the AC receptacle. You find the wire leaving the bulb and put the LED Keeper on that string. You pull the trigger and it punctures the wire, lighting the rest of the string.

Does anyone know how this works in theory? I was under the impression strings are usually wired in series. If you're by-passing any bulbs, essentially removing them from the circuit, wouldn't that increase the voltage drop across each bulb and wouldn't you risk burning them out?

Thanks!

[stj]

Re: How the LED Keeper Works

i think i'v seen a video of this by electroboom.

dangerous as hell, because it was intended for incan x-mas lights.
ion led strings if it's a series set you need to short it, but if you short a parallel set - boom.
you could use a resistor, but what value?
and your still damaging the insulation.

[R_J]

Re: How the LED Keeper Works

All it is is a led tester, it will locate the defective lamp so you can either replace the bad lamp or replace the bad socket (PODS) it does not bypass the circuit.
It is similar to those led testers for backlight led testing

[eccerr0r]

Re: How the LED Keeper Works

yeah pretty simple constant current source and insulation piercing solution, should only work with LEDs as it can't source enough current for incandescent bulbs.

It looks like it uses those "pods" to short out (or rather use a 33 ohm resistor) opened sockets/LED bulbs. They could have gone one step further and "pod"ded another LED there, but chances are it'd look different and people would rather a dark spot than some weird looking LED?

I was hoping it was doing some inductive/RF method to find breaks in the circuit, but nonesuch luck, vampire testing through insulation is unacceptable to me...

[R_J]

Re: How the LED Keeper Works

or replace the bad socket (PODS) it does not bypass the circuit.

I was wrong

[Spork Schivago]

Re: How the LED Keeper Works

Those pods don't look like LED replacement sockets to me. I think eccerr0r is correct, and it's just a "dummy" load with no LED.

I'm more interested in how the device works when it powers a previously unlit section of the strong. It pierces the wire after you find a bad LED, but let's say there's 4 LEDs before the pierce on that series. To me, it seems like it's changing the circuit, by removing the lights before the pierce from the string from the circuit.

Is that not what's happening?

[eccerr0r]

Re: How the LED Keeper Works

that's what it looks like what it's doing, just generating a, say, fixed 1mA current source and the pierce will complete the circuit when the original LED could not, breaking the circuit, because its die bond or socket broke.

Pretty primitive I think. I just wonder how many volts max it will generate to light strings of LEDs, that's the trick...

[Spork Schivago]

Re: How the LED Keeper Works

that's what it looks like what it's doing, just generating a, say, fixed 1mA current source and the pierce will complete the circuit when the original LED could not, breaking the circuit, because its die bond or socket broke.

Pretty primitive I think. I just wonder how many volts max it will generate to light strings of LEDs, that's the trick...

Yeah, that's where I'm getting a bit confused I think. The voltage that it generates to light the string of LEDs, without it knowing ahead of time how many LEDs need to be lighted.

To me, it seems it'd work just like this. Say I put the device after the 5th LED. That would be equivalent to just shorting out the previous 5 LEDs, right? The voltage drop across each LED would increase, if it was a series circuit, and possibly damage the remaining LEDs...

[R_J]

Re: How the LED Keeper Works

I guess I was wrong, they are just resistors not replacement sockets. I'm sure they could have made a socket that clips on the same way.

[eccerr0r]

Re: How the LED Keeper Works

(If it is)/(It should be) a fixed constant current source, the LEDs on the string will automatically reduce the voltage to a safe voltage due to their intrinsic voltage drop - and it wouldn't matter how many LEDs are in the string as long as it's within the range of the CC source.

[redwire]

Re: How the LED Keeper Works

The good (light string) lamp testers (incandescent) use a non-contacting electric-field sensor.
Sort of like a non-contacting voltage (NCV) probe, except it does not use the handle/case as one electrode. It has two tiny electrodes in the probe you put on top of a lamp and move along the string, lamp by lamp.

At a lamp that is open-circuit, you will get a 120VAC electric-field across the lamp, for either LED or incandescent.

It's better than breaking the insulation and piercing the wire, outdoor light strings always get wet...

[Spork Schivago]

Re: How the LED Keeper Works

I guess I was wrong, they are just resistors not replacement sockets. I'm sure they could have made a socket that clips on the same way.

Yeah, I watched the video. I think the reason they didn't was to make it more universal. For example, we've noticed the LED lights from icicles might not be compatible with the LED lights from our 5mm ultra-wide straight strands or whatever you call them.

I bet with a little heat shrink tubing and a donor set though, you could easily replace the broken socket with another socket.

My mother-in-law brought us a whole bunch of LED net lights that didn't work. With one set, it was like half the LEDs were bad! We used that set as a donor set to the get the other ones working.

I'm not sure what happened that took out half the lights in that string. My only guess would be some sort of surge. I believe LED strands usually have some sort of current limiter. Perhaps one of the current limiters failed? I dunno.

[Spork Schivago]

Re: How the LED Keeper Works

The good (light string) lamp testers (incandescent) use a non-contacting electric-field sensor.
Sort of like a non-contacting voltage (NCV) probe, except it does not use the handle/case as one electrode. It has two tiny electrodes in the probe you put on top of a lamp and move along the string, lamp by lamp.

At a lamp that is open-circuit, you will get a 120VAC electric-field across the lamp, for either LED or incandescent.

It's better than breaking the insulation and piercing the wire, outdoor light strings always get wet...

I agree. Do you have a link to one of these testers that would work with LED as well? Thanks!

[redwire]

Re: How the LED Keeper Works

LightKeeper-Pro
https://www.homedepot.com/p/LightKee...3-CD/100686478

Actually, you might be able to use a NCV tester and just move along the string, as in the video. I haven't tried that.

[Spork Schivago]

Re: How the LED Keeper Works

LightKeeper-Pro
https://www.homedepot.com/p/LightKee...3-CD/100686478

Actually, you might be able to use a NCV tester and just move along the string, as in the video. I haven't tried that.

We have that Home Depot's LightKeeper Pro and just could never get it to work properly...we could only use it if we manually pulled a bulb and put it on the prongs, which didn't really work with LEDs...

[redwire]

Re: How the LED Keeper Works

The NVC tester is seeing the E-field difference between your hand and the probe tip. If your other hand holds the string close to Line or Neutral wire, or has no stray capacitance to ground, you get mixed results. Or if you hold the tester in your hand, far from the pcb and batteries it will not pick up much.

The old one I had was two prongs for the probe that went almost around the lamp, like a cup. It looked at the E-field inside the cup and didn't care or work as you moved along the string. Like a differential probe.

I've never seen a difference with (series) LED strings. But some strings keep working when an LED or lamp fails, they have extra parts.

Another way is to use an audio signal tracer and listen to the hum as you move the probe along the string. I have an LM386 box I use.

[Spork Schivago]

Re: How the LED Keeper Works

The NVC tester is seeing the E-field difference between your hand and the probe tip. If your other hand holds the string close to Line or Neutral wire, or has no stray capacitance to ground, you get mixed results. Or if you hold the tester in your hand, far from the pcb and batteries it will not pick up much.

The old one I had was two prongs for the probe that went almost around the lamp, like a cup. It looked at the E-field inside the cup and didn't care or work as you moved along the string. Like a differential probe.

I've never seen a difference with (series) LED strings. But some strings keep working when an LED or lamp fails, they have extra parts.

Another way is to use an audio signal tracer and listen to the hum as you move the probe along the string. I have an LM386 box I use.

I will try it again when we put up our christmas lights. I probably wasn't using it correctly! I have to admit, I never used it on LED lights. My father borrowed it once for his lights and I didn't realize they were LED. He manually pulled a diode and fry it each time (or have the polarity reversed and it wouldn't light at all).

Thanks for sharing the info! I do have a probe generator / wire tracer. It only works on non-energized wires. It's the Fluke Pro 3000 Probe and Tune:

https://www.homedepot.com/p/Fluke-Ne...-900/202290922