Here's a blast in the past. This is a project i did back in 2004 and i just went through a spell at building loads of these units using very early gallium, nitride leds, it's when they just became affordable. They were selling them from companies like bhk. In fact, one of these had bhq bhk best hong kong, who were selling the bulk leds on ebay at an affordable price.

I mean they were basically dumpster leds, but you know at the time it was pretty good. I can demonstrate just how dumpster they were, but before i go do that, though uh this led panel, is there any flicker you're not seeing it flicker, it should be a bit flicker, there's no smoothing it's drawing almost 7 watts of power, 29 milliamps and a power Factor 0.9, because it was a resistive current limiter to these. They also get quite warm, that's not really surprising, and in the case of this one well, let me plug it in. Let me find its plug.

For a start, this was the super slim panel version uh with all the circuitry in the back and uh. It is looking a bit sad uh. Some of the leds are out. The other ones have actually changed color.

These might have been chai wing uh, which was another ebay seller, equally craft leds, but it's what we had at the time. That's very shiny! Isn't it this thing, projects a nice beam and you might not think that's very bright. It is drawing in this case about five watts and when i point it at a wall, it projects a very visible beam of light. It's very bright and that's why i use these.

I was partly using them to test the leds, but i was also making uh decorative lights that could just be left on all the time. Well, these kind of showed a bit of heat problems, but it also you put it behind furnishings and it just splashed light up. There's no smoothie in these uh, so i'm quite surprised it's not showing ripple in the camera. I shall plug in some random ones.

Here. That's uh not sure. If that's, i think that is blue uh one of them is ultraviolet. I think it's.

This one was ultraviolet yeah. It is because uh it was early ultraviolet leds, the near ultraviolet, a very deep, blue and uh. This one does make things fluoresce. Quite brightly, but anyway, let's explore the circuitry.

Let's open some of them and see what i was up to 18 years ago, which is quite some time ago. It seems to have blown by very quickly so i'll show you the schematic of these first, it's very, very simple uh. It is a bridge rectifier i'll, just zoom down onto that uh mains command in this case 240 volts uh ac, coming in going through a discrete bridge, rectifier, then just resistors to limit the current and then the leds and that's very much like modern, led lamps. That use the linear current regulator, but in this case, because it was just resistors, if you get too close to the mains voltage of the leds, if you get too many leds, it means that any slight voltage fluctuation causes them to change in intensity.

You see that with some of the cheaper led lamps, let's open some of these up where's a suitable screwdriver. There is a suitable screwdriver. It's nice! Looking back on projects like this just to see what i was up to, sometimes i feel like revisiting them, especially with the possibility of using 3d printed cases. These days, these ones are hammond cases made in canada.

This this light is warm, that's quite snuggly worm. I made a red one of these and gave it to my brother as a heated therapy lamp that he could use in his a sore shoulder from lifting coffins, which is what he did so this one i called it gallium. Can i use that name a lot. This one has a satellite circuit board with the bridge right fire on it and then just three 1k resistors rated two watts each.

I don't know what they were actually being used at hmm, but that would have been basically six watts worth of power rating. Although i wouldn't use a resist, a two watt, resistor anywhere near two watts, i would say they were well under one watt dissipation each because most of the voltages were being dropped across leds uh. Let me work this out. One two, three, four, five, six, seven, eight! Nine ten ten times six, sixty leds that'd be about 180 volts being dropped across that, so really the voltage being dropped.

The rms voltage being dropped across the resistors was only about 60 volts, 20 volts each 20 milliamps one key, that's that fits in perfectly for this. Let's take a look at this one, which is different. I went through quite a few revisions at that time with surface moon components. This suddenly makes it very viable for revisiting this project because there's a lot to be said for the simplicity of just resistors and leds, particularly if you were to add in a bit of simple two transistor circuitry, to make a linear current regulator.

It wouldn't have to be too fancy, so what we've got here we've got. I included a fusible resistor wow, a 100 ohm resistor before the bridge rectifier, and then the rectified ac, coming down clive 2004 to the circuit board, which has resistors interspersed along here. That one is a 0 ohm resistor so and this one down here, so i was fine tuning the resistor values, just like they do in modern lamps. That's kind of interesting um and in this case the resistors were mounted through holes, but they were soldered in before the leds and then the leads crops.

You can't actually get your fingers and touch. Those bare leads interesting, so this one is another one of these. This one is another one of the this type, but this one has got locking nuts on it right. Tell you what one moment please, i'm just going to pause while i take these off, so we can take a look at the circuit board.

Okay - let's get closer to this one, this one had the redirect far on the back and then the resistors in between the leds again, but because these holes are coming all the way through to make sure the leads didn't protrude through too far. I can remember this uh, i formed the diodes, but then cropped the lead, so they just barely poked halfway through the circuit board, so you couldn't make contact with the back not perfectly ideal. This is where the surface mount m7 type. Diodes are probably quite good, but again in this case it's a value of those.

I think it's 220 ohm, 220 ohm resistors one, two, three, four, five, that's roughly making the 1k again, isn't it so it's a very standardized value, pretty good. These worked well these days. If i was revisiting it, let's bring in the schematic again, i might add an electrolytic capacitor across here, because that would potentially reduce the flicker might pop a little inrush limiting resistor there uh definitely a discharge resistor across that capacitor and then nudge either add more leds Or more resistors, probably more leds - to use the higher voltage, because, whereas it's 240 volt rms, it would have been about 330 volts. So maybe i'd have gone for the best part of like 100 leds.

For that, but interesting project very interesting. I do strongly get the urge to revisit this again because they worked pretty well. I did push some of the leds quite hard in these, partly because companies like bhk were saying the modern leds can take 30 milliamps in reality, no, they couldn't you're better. Actually, sticking down to about 15 milliamps, so i would well under run them so use higher value resistors, but pretty neat yep.

I think i need to revisit that project again because uh it was good. I liked that project at the time i made lots of them. As you can see, these are just a few of the ones. I made note that uh.

This is the lid for that case, so double value, some of them were built into the box, and some of them were just built into the lid. Pretty good yeah, definitely worth a revisit.