Led sign modules: i've got two types here. This type that i've got lit are 12 volt dc modules also available as 24 volt version, but this one set that aren't lit at the moment are 220 volt, 240 volt modules and all the circuitry is inside these to drive the leds and they're, not very big. Quite intrigued, looking forward to taking one of these apart to see what the circuitry is. All i can see through the front is two resistors.

I hope it's not just resistors, but you never know so. These are used a lot where neon used to be used or the fluorescent tubes used to be used in the case of a big box sign. You may just have a couple of 12-volt power supplies inside and these zigzag along in the back behind the plastic, and they can either be applied with double-sided tape. What's this type, it's a 3m clone they're, both 3m clones.

Aren't they, but it's how they get the double-sided tape or you've got a little hole here that you can put a screw through to actually clamp them into place and in the case of channel letters, if it's the front illuminated front face, you'll find these inside mounts. In the back say, it was the letter: u you'll, just find them shaped round inside with a low voltage, keep going into them lighting the front plastic from the back or if it's the silhouette type, these will be mounted in reverse they'll, be mounted in the front Of the letter pointing in and it will just create a splash of light at the back, they also have uses in cars and vans, because you can use them as a very convenient alternative to led tape for general illumination. The back you can get kits on ebay, where they just sell strips of this purely for in van illumination and they've got the edge over the tape and they're easier to install uh, because you can just basically along just sticking each module up at a time and They can also ground corners easier than the uh. The standard tape they're also a proven technology.

I mean there are crap ones on sale on ebay, but there are, most of them are kind of refined, now they're more reliable than they used to be so this version. The reason i bought these in the first place. Well i'll show you i'm going to warn you in advance that these shimmer and flicker, because they appear to be well basically, there's no capacitor. So these are going to shimmer and flicker be aware of that.

It's not too bad, but there is a distinct shimmer not to the naked eye, but the camera is doing a great job, picking it up um it's showing about 12 watts, it's showing at a sensational power factor of 0.947 uh and a current of 51 milliamps uh. Let's do some maps shall we let's bring the kink calculator in, so i've actually got nine modules, 12 watts divided by nine. So each of these is about 1.33 watts. Um 51 milliamps five 0.051 uh, divided by the nine modules, is about five or six milliamps uh per module.

So you could run a lot of these. That's one advantage, but i wonder how reliable they'd be in the sense that you know if one module went down. If it went bang and uh something failed like a rectifier or some other electronic opponent, it could actually take down the whole string and it'd be quite hard to find, which one that's a slight parallel of that. But it gets rid of the need for the power supplies either way.

These modules all typically cost about one pound. They come in about one pound per module and you get them in strings like you can get them just as an individual module or you can buy 20 as i did, or you can get a whole roll of a hundred and just use them as desired right. We'll tell you what uh i'm going to i've already had a go at trying to open one of these. They are sealed, absolutely mega shot.

They are fused together, so um and it seems to the cables look like they're injection molded in so i'm going to pause. I'm going to try and take these to bits. One moment please well, that was incredibly messy. I ended up having to literally dremel them out to get into this very difficult.

The plastic is so fused on it. It must be similar plastics to make sure that the injection molding they fuse together really well, and it's interesting that, because they are injection molded in uh, the circuit board for the 240v, one has electronic components in the back as a linear regulator, and you can actually See the outline when i peeled it off it lifted one end of the bridge rectifier and because the components themselves were embedded tightly into the plastic. It's quite an interesting construction. But anyway, let's analyze the circuitry.

I shall show you a zoomed up image of both the 12 volt and the uh, the 240 volt one. So let's zoom right in and we'll start with the 12 volt one, the 12 volt strip, because it's working a higher current. This is where the advantage of the 24 volt stuff, probably with more leds uh. It means that for a given intensity, it will be about half the current, so you can run twice as many once a particular cable size.

It just means there's less drop across the run. The 12 volt one has big thick bus bars in the back and on the front it has a leds that apparently have three chips: each because there's one resistor, one 91 ohm resistor per led - and i can see little rectangular block in here. That does suggest it's a triple chip led. So the positive connection goes to each leds and the negative connection comes up to the resistors and then goes through these of light-colored ones and tracks here just to connect it's very simple.

It just literally, is the leds and series with the uh resistors, the mains voltage. One is a lot more complex. Let's move this up here on the front. It's got three multi-chip leds in series.

Now i actually tacked you can see the resist that the rectifier here has quite shiny pads in the output, the plus minus i tacked a 4.7 microfarad, 400 volt capacitor across that and then put a limiting current limiting resistor in to avoid overheating. The regulator here and i just passed enough current to make the leds glow, so i could get a voltage measure across them. I measured 72 volts across them now. I would estimate that at 72 volts i would estimate that the current i was running them.

It's only going to be about 2.5 volts across each chip that would suggest around about 28 chips or so in each. So these are quite high voltage and 28 volts um. It could be 24 to 28, but 28 say times the three volts of the fully full intensity led that's going to be about 86 volts per led. It really adds up to a high value.

I do not know what the 470 ohm resistors are for. There's very little voltage across them because it's only about 6 milliamps that was passing through the circuit uh very odd, but anyway here is the circuitry. This time with the neutral, the bus bars are much thinner because the current for the whole thing is much lower. So we have the neutral bus bar this blue one coming right up and going straight out the other end of the module, so the wires can loop out.

However, the live to allow room for the sp space for the circuitry. The live bus bar goes through. These six plated through holes runs on the other side, dots back through with six plated through holes. I shall just add the missing plated through holes and then goes on.

The neutral drops down to the direct fire and likewise the live bus bar from the back comes through pleated through holes to the bridge rectifier. So it's basically across live and neutral. The output. The positive then goes through and to the leds runs through that high voltage led resistor, high voltage, led resistor, high voltage, led and then back to the linear regulator, the linear regulator and because uh i'd already used blue for the neutral.

I've used green for the negative. Here the green from the redirect file comes to the sense, resistor and the regulator and then the sense resistor goes to one of the pins and then it goes to the leds. So it's a very simple linear regulator. It's going to dissipate a little bit of heat, but given the voltage of these leds, it's not going to be too dramatic right schematics.

Let's take a look at the schematics, so we'll start with the 12 volt one here. It is very simple schematic um, the bus bar is going through. The each of these is one led, but it's actually got three chips in it, um in the case of these ones. It looks like a continuous chip, so i'm guessing it's going to be the one that has a little line like that leading to another line like that.

Another line like that and then a pad going out uh with just a bond wire going on to each end and they're all basically on the same substrate but they're divided into multiple chips. In the case of the other one. It's probably the array would be much more complex. It's going to be a massive array of chips that just basically just zigzag, perhaps and forwards from one end to the other, with like a connection point at each corner.

It seems a common way of doing things. These days, surprise voltage leds, it's actually the best way to run them on the high voltages, and i screwed up here. I've put the full current, but it's about 35 milliamps. You can see where i've used the tip x to hide my error, but it's about 35 milliamps running through each of these um.

I measured 107 milliamps, which was roughly 1.3 watts, did i say, 1.7 silly amps that would 107 milliamps. I noted that if you turn the voltage down from 12 volt hours recommend doing this to 11 volts. This is where it's really handy. Having the power supplies with the adjustable voltage, i use tend to use meanwhile uh because they do usually have their little voltage adjuster on them, even the waterproof ones.

But if you turn it down to 11 volts, it drops 107 milliamps down to 80 milliamps, which is uh only 0.3 watts per led, which is a a significant drop, but the intensity when you turn it down from 12 to 11 volts, the intensity doesn't visually drop. That much but the lifespan will go up as usual. Let's take a look at the much more interesting. This simple, it's ridiculously simple: the mains voltage one.

It lacks a capacitor, but you know what the capacitor is the bit it would fail. We have the live bus bar going from one end to the other. We have the neutral bus bar going from one end to the other. We have the bridge rectifier just tapped across those and then the positive going through led resistor led resistor led and then to this little current regulating chip, which has a non-standard number um.

Let me see if i can read that. Let me see if we can read that number ibm c k c t i drew a blank and that then that looks like a custom number, the only other number on it looked like a date code, but that's one of those little current regulations like regulators that The car goes through the leds and then it goes through this resistor and it measures voltage across the resistor to limit it to that six or so milliamps that it is running and these leds they are the 72 volt leds. I noticed that maybe this is why it's such a good power factor. If this is the rectified waveform, i would say that it was lighting for a good chunk of that waveform and it only dips out for about the bottom 30 percent of the sine wave.

So when you shake the leds backwards forward, you can see that flicker and the cameras will pick it up, but to the naked eye. It's actually pretty good, which is unusual, given how many chips are in each of these leds, what they combine for voltages. So, what's the bit that's going to fail in this if the this bit fails, it'll, probably pop a wire bond in the led and it'll fail in a controlled manner. If the rectifier fails, it will probably clamp the supply and uh.

The only way to clear that would be to you do destructive high current pulse type techniques to find uh. If you could try and blow the fault clear, but the potential with things like this is it could take the whole string of leds out. So that's interesting. The thing that actually got me interested in these recently was when a chinese marketer er invaded a technical signage for him and every post.

They were saying you, like my led modules you buy. I have 220, i have 120 volt and i was thinking it's. I don't really care much. Spam was actually quite rude to her because she was a a spamming, uh technical form, but i thought what's in these and i actually looked online and found some on ebay and bought some and uh it turns out.

The secretary is very different to what i was expecting. It is fairly efficient. The secret is down purely to these uh high voltage leds that mean there's very little left to drop over well, these resistors aren't doing an awful lot. This little component is doing a bit, but it doesn't leave much to drop well.

Both these circuit boards, by the way, are not aluminium core. Some of the better quality ones have an aluminium core pcb in them to help dissipate the heat a bit, but keep in mind that they're then stuck on with double-sided foam tape. So it's you know it's kind of, like i suppose, as long as they keep the power low enough they're not going to get too hot, but they're interesting, they're also available in a selection of colors. And if you go for the super trashy ones from ebay, which will fail quite quickly, probably they're certainly used to no days it's just a rectangular box with the led, almost like a section of led tape, just sat into it and then just flooded with resin, with The wires coming out, i've ordered some of those too to test them, but these ones are quite nice.

It's a nice construction and the circuitry is not what i expected. It's actually quite neat for the high voltage ones, pretty good, interesting stuff.