Controlling RGB LEDs with only powerlines: Anatomy of a Christmas light string

This is modern electronic design in a nutshell.<p>The large-scale physical design is as simple as possible (just regular wiring), the individual components are all &quot;smart&quot; (Christmas lights each with their own integrated IC, doesn&#x27;t get more embedded than that) and addressable via a communication protocol.<p>Imagine how difficult the wiring would be to have 100 addressable lights that didn&#x27;t use this arrangement!

This string is only &quot;slightly addressable&quot; - in a string of 100 LEDs, you can&#x27;t display any arbitrary image.<p>With small changes though, they could have allowed arbitrary addressing, which would have made these LEDs applicable for a far wider variety of products.<p>One way would be to deliberately make the string of LED&#x27;s reflect the signal back from the unterminated end of the string. Then, make each LED only respond if the reflection and original signal add up past a threshold.<p>The controller can then have an initialisation step where it &#x27;discovers&#x27; all the functioning LED&#x27;s and their position on the line (by looking at the power draw when commanding them to turn on).<p>The downside is you&#x27;d be sending GHz bandwidth pulses down a poorly controlled pair of wires, and sharp bends and stuff might leak rather a lot of RF.

There&#x27;s one part about the article that I&#x27;d like confirmation about: does this mean that the LEDs come out of the factory already configured as belonging to one of the 6 zones? This would be as opposed to, say, WS2812 LED packages where they are identical.

I&#x27;m really excited for the inevitable improved version of this that supports binary addresses and setting approximate PWM brightness levels.<p>Given the manufacturing process[0] linked, it could be a _little_ tricky to actually assign a known ID to each light in the strand, but either using the placement order when the strand is made or using a stochastic process to randomize the IDs and subsequently calibrate the strand should be viable, and result in a low cost strand with WS2812-like capabilities.<p>[0]: <a href="https:&#x2F;&#x2F;youtu.be&#x2F;wCKlCUBsaT4" rel="nofollow">https:&#x2F;&#x2F;youtu.be&#x2F;wCKlCUBsaT4</a>

I love electronics and electrical engineering in general. But this article explains perfectly why it is less accessible than software engineering - the former requires a individual components, soldering iron(s), a digital oscilloscope, etc. while all you need is access to a computer with internet for the latter.

The video of the manufacturing process is quite interesting. A lot of human labor is involved.

One downside to this type of Christmas lights is that these design parameters — i.e., make it possible to manufacture feature-rich novelties with a minimum of wiring and changes to the assembly line — result in a product that has no user-serviceable parts: when a few LEDs die, the whole product should be thrown out.<p>I say &#x27;should&#x27; not because I think so, but because this is literally what is written on the labels affixed to many such products. We went from lights featuring incandescent light bulbs which came with a few spares in the box (anyone could replace those), to LED lights with a few spares (finicky to replace, but doable), to almost exclusively fixed-in-place LED lights without replacements and labels attached that tell the user to throw the chain out when lights break. And now more and more complexity with integrated ICs.<p>Only those of us with a soldering iron can salvage some of them, and this new category seems like it might not be repairable at all (excepting the really clever EE folk like the author). Environmentally speaking, the increased complexity and focus on ease of manufacturing of such products seems to reduce their lifespan as well, with repairability already at a minimum.