This is an unusual item and it's got a little story behind it. It is an underwater lure light. The idea is, and i'm not an expert in fishing. You guys can keep me writing this.

The idea is that you throw it into the water at night, and the fish are attracted towards it and it has a long lead. It has a little switch part the way along the cable, and it has a couple of crocodile clips to contour battery. So i show who got onto a battery and show you this. This is available in a few different colors each, i suppose, for a specific style of fish.

This one is blue. Just because i thought blue would be quite nice. I wanted to try it in the local lake with jellyfish, but there are no jellyfish at the moment. I shall turn it on and it lights bright, blue.

This thing is designed for 12 volts. It self regulates at up to 11 volts the current gradually increases, and then it starts kicking back as the regulation sets, and it will aim for about four watts. So it's designed to cover the sort of general sort of charge state of a sealed lead acid battery. Although you could use lithium these days as well, i should turn this back off.

So is it? Is it good sportsmanship to do things like this? I'm not really sure. However, what is unsporting is that when i bought this from ebay, the i got the notification. It's been shipped and i wonder if it was through a third party, they shipped it and they had to ship something because initially an envelope arrived and it i opened up thinking. What's this, it feels really light.

There was a cork inside and i worked out. It was this item that was missing from the batch orders. I've made recently, so i contacted them and said uh this cork just arrived and they said. Oh yeah, we're sorry we ship item.

It is on weight, yes and uh. That cork is gift, so they basically fulfilled the requirement of shipping something out. So i wasn't expecting this to arrive and i was carefully monitoring the uh, the point at which you could open the dispute if it didn't arrive, because it took a very long time it. Finally, arrived unexpectedly through the post, so um, i can tell you actually by turning this on again.

Well, i can tell you that the voltage it starts lighting at is just over 7 volts. So is that right hold on? Let me just let me just double check this: let's get evidence to prove what i say: um i've got the bench power supply here. I turn it down. It starts to glimmer.

It's dropped down to about one milliamps at about eight volts. So, based on that, i would say that, especially with the switching regulator as well, eight divided by about three i reckon it's multiples of three 2.6 volts sounds about right for a blue led at that level. I reckon it's a cluster of three leds in series, but in this each of these strips, which has 24 out of 12 leds and there'll, be four sets in parallel, and likewise this one in the end also has four. So it's basically uh three in series, but four sets of those in parallel on each of these circuit boards.

It adds up to quite a few leds. I didn't actually count the leds that was most remiss of me uh hold on. Let me see one seven. Eight, nine, nine! Oh that's quite a lot of leds nine times the 12 leds.

It's 108 leds, uh 4 watts divided by 108, equals about 37 milliwatts per led they're just running about 10 um, 11 ish milliamps each that's all right! Actually, but the overall heat in this package will get quite hot, however, where would the water get in? Would it get in at this point here? It does seem quite well sealed we'll open it up, or would you get in here this? What looks like silver tape is actually just printed on. I think that basically well deposited on there's. No, it feels initially like tape, but you can't get your finger underneath it. So it's a coating, the surface.

I don't think i'm going to be able to get this off just by squeezing it. I shall give it a go. If it doesn't come off, i shall use the vise of knowledge, i'm sure it's making the crunching noises. Is it plastic or is it my fingers? Oh no, it's coming out.

Oh, and there is a little regulator. Oh they've gone to decent efforts. Look at that they've put sealant around the cable coming in. This is good, a siliconish type sealant, and also here, that's quite neat, uh.

What's the total regulator, this is where i make a complete dick of myself by not being able to read the number in that big, tiny. It's not too bad. 1350 uh, it's a little uh buck regulator. These are these two sense: resistors uh, 0.5, ohm and 0.5.

Ohms so that they're, probably in parallel to give 0.25 and but i shall check this out - let's dig in let's get into this - we shall scrape out the shmur and get into this and see if we can pull any more out, not that you know, there's not Going to be an awful lot really in here is a series parallel array of leds. Am i going to burst something here, i'll, just pull the cable? Oh, that birthday, something this isn't surprising. Is it big, ham-fisted, clive uh? Is that sealed onto the side then, or is it just some of these tend to be friction fit? I should stay more central shouldn't i what if i squeeze it a bit more? What if i no, i was going to bang on the table. That would be deafening if you get headphones on.

So it's not a good idea. Is it what's the pos? No, it's moving it's moving. Oh! It's got that we think there's that we lip at the edge that always stops it coming out right. Tell you what i'm just going to pause momentarily while i bang this really loudly right.

Well, that's the diode pulled off and the inductor broken. I'm not doing very well, i'm just going to go full destruction here that probably also made a loud noise in the microphone. Sorry up, let's get this out destruction style. This is a complete disassembly and i think to be honest that, oh just possibly, i shall get the soldering iron on and i shall desolder the end here.

So we can actually take look inside. I don't think there's going to be anything in here, but it'll be interesting to see the configuration. Actually, i can see the configuration there is nothing in here. There's the regulator uh, it's i don't think there's any resistors or anything in the back of these right.

One. One please i'm just going to probe this. That was quite hard to reverse engineer, because initially i thought i'd located the chip, the 1350 and it turns out i had, but i wasn't getting continuity from the negative to the negative pin, the chip or the positive to the positive in the chip. If i'd looked at the meter instead, just listening for continuity, i'd have discovered that, on the back of this circuit board on the other side of this, one are four diodes schottky diodes forming a bridge rectifier, which means that this lamp module is a universal module.

It can be used on ac or dc, so it's probably just you know a standard 12 volt lamp that has been adapted for this application, which would make sense, particularly since really all they've done, is change the base, but the chip in question the 1350 turns out To be, i'm not sure if it's a masked coffee, don't know it's one of those chips every day has their own version. It turns out to be a little buck regulator and the circuitry is more or less as they've got it, but it's quite odd uh. I shall zoom down a bit so yes, more or less the circuitry except they've swapped the position of the inductor and the leds uh. It's interesting to show our three leds and series here, which kind of fits that and there's also a capacitor across that i get the feeling this might be designed for mr16 style lamps, but uh.

Yes, i shall show you the schematic shortly, but here is the chip. Here are the current sense resistors two half ohm resistors in parallel uh there was the inductor before i snapped off and there was the shortcut before i snapped off the power supply. So a smoothing, capacitor and then a little capacitor here across the leds, that's more or less it. Let me bring in the schematic here is the schematic incoming supply, the bridge racked far made of discrete diodes on the other side, that smoothing capacitor, just basically a local buffer capacitor, going straight to the 135o chip? It has the positive negative as the current sense and the lx lx switches to the negative rail via a little internal mosfet.

I think it's a mosfet is it it would probably be it's a mosfet. This is interesting because they've got a little comparator here. Uh for sensing, the current sense resistors, normally the current sense resistors would actually go through lx and then to the zero volt rail, but in this instance, they've actually put them in the other end of the circuitry, probably to keep the pin down count down on this Chip, so we get the current sensor resistors here and the voltage across them being measured being between the positive rail and current sense. We've got the inductor, we've got the leds and that little smooth capacitor across the leds and then we've got a short key diode in the opposite direction and the sequence of operation is this: the chip turns on the mosfet and it effectively bridges lx to the zero Volt rail here the negative current starts flowing through the resistors and it throws through the inductor, building up a magnetic field.

Initially, the inductor will push back. It will limit the current. It also flows through the leds. Then this current sense detects this.

At a threshold of current flow through and it turns uh the lx off it, it leaves it floating it switches away from the negative rail at that point, this had been positive and this had been negative now the magnetic field collapses - and this end was positive, and This end was negative when that happens. It finds another current path, which is through the leds through that schottky diode, the free field diode and back through the current sense resistor to the other end of the inductor. It's a very straightforward circuit. It was a lot easier to explain that most reverse engineer, but that's a minor technicality that is the curse of these all-white circuit boards, particularly when it's actually dotting backwards and forwards between the layers.

The leds on the side of the unit have a couple of formats. Well, there's actually three different type of circuit boards. The standard format for them all is that you've got the positive at the bottom, which is a down at the bottom here, and it goes through uh, four separate circuits of three leds and there's a tiny little track coming out the side here and there's a tiny Little track going up the side there to connect the negatives, and that means that there is a common bus going up to the top via another circuit board. But the negative for all the standard circuit boards is fed from the top end and the positive is fed from the bottom.

The other oddity here we've got the positive and negative here, but it's actually going through the circuit board. I think actually, no, i'm just suddenly realized something it's kind of going through the circuit board there. It is it's actually bridging onto our side. So when it's doing that uh it's transferring it's got pads on the other side, it tracks the other side.

It's doing the same as this, but it's also going up to two pads up here: to transfer the positive and negative, both onto the actual the top circuit board. The top circuit board itself is of just a rhythmic pattern of leds. It is a common positive that goes around the whole outside and then it goes through each of these gripped leds and then there's plated through hole onto the other side under each of the negative connections. So it's just four circuits of three leds in parallel.

That's very straightforward: again: it didn't take long to explain, took a lot less time to explain than it took to reverse engineer. That is an understatement. So that's interesting! The question is, i could get this going, but even though i've ripped the inductor off, i could just put a resistor on and i could actually uh or a couple of resistance. I could get the leds just going straight off dc, but the question is: are these effective? Do they actually lure the fish and why would the fish head towards the light i have come across uh in salmon farms? They had some sort of thing.

It might have. Actually been for rogue things in the salmon pools that they were attracted to pulsing flashing lights in some way. Maybe it was the thing that's how they found their way to the actual salmon was the reflection of the skills, but that uh attract them. That way, but i don't know um they do them in blue.

They do them in green, i'm not sure what colors fish respond to. But there we go. It's an interesting little thing. Let me know if you've ever used, one of these led lures and whether it actually worked or not.