LED Strips

There a lot of options for colour LED strips.

I am talking pretty much entirely about 5x5mm individually addressable full colour LED modules on a 10mm wide flexible PCB with leads at each end. But even being that specific there are a lot of choices!

These things basically...

Covering/backing

Start with something simple - these strips often have options.

• Black or white strip supporting the LEDs.
• A domed flexible clear covering that is generally pretty waterproof.
• A rectangular sleeve enclosing the string, which is more waterproof.

This is really a simple choice. I have some on a door frame which are the domed covering, because the strip or chips would snag otherwise. I have some on a shelf (image above) with no covering, as out off reach. You need to consider this if putting in some sort of diffuser, e.g. an aluminium strip with plastic cover - where no covering in the strip itself helps much under the diffuser. A diffuser is usually a good idea.

Now, some do come in a diffuse housing, which can be a good compromise. Bear in mind that any covering or enclosure makes cutting to length and joining harder. The simplest is the bare strip with LEDs on it (and the pads between them) allowing easily soldered joints to another strip. There are clips you can get but I do not recommend them - soldier it.

Note - the adhesive backing is pretty universally crap, not bad on aluminium, but on wood, etc, not good. I'd think about some nice 3M tape.

Density

Again a pretty simple one - how close the LEDs are - and that varies.

1. Close together is great for sheer amount of light, and using inside any sort of diffuser strip as you can hide that there are individual LEDs.
2. Close together means more LEDs and so more power needed.
3. Close together adds to the cost.

Voltage

This is a bit more complex. The main choices are 5V, 12V or 24V. I am generally working towards 12V these days (with per pixel control on a WS2815).

1. 5V can mean notable voltage drop on long runs, meaning power feed in at extra points. 12V can run longer and typically the modules can work on much less than the full 12V if they are per pixel 12V.
2. 12V and 24V can be multiple pixels on one controller, e.g. 3 RGB pixels on one controller in a row are controlled together as the 12V is split over them. This is pretty shit, to be honest. It is not always the case, and WS2815 seem to be ideal with single 12V working pixels separately addressable.
3. Higher voltage is lower current and can be a smaller power supply and less heavy duty power leads.

Current

This is one of the big issues, and not as simple as it looks - the LEDs do not use a lot of power, but there are a lot of them. Higher voltage means you can work with lower current. But you have to be careful, even with 5V DC levels, if you have hundreds of amps available - that can be nasty stuff (not that is unlikely to electrocute you, but can burn and melt stuff - a short at that power can melt copper wires).

The other issue, apart from not wanting to handle large currents (for which higher voltages help) is the power supply itself. A high current power supply is bulky and expensive.

A big challenge is working it out - and this can easily go wrong. There are guides and tools and data sheets. But you can easily find you are massively over specifying your requirements. As with any modern electronics, LEDs are getting more efficient and so lower power - the guides for 10 years ago do not apply now.

You also have the option of not lighting all LEDs full white all the time. So depends what you want. In practice you probably do want almost any system to work at all LEDs on full - but not always!

In short, my recommendation is to test the strips you are using, get a current meter, a strip and set to full power all on. Measure it. Note if can change on temperature, so leave a little overhead. But that tells you what you need.

Bear in mind voltage drop is also a thing - all white on a long strip could have more than enough current from the supply but still fade and lose colours at the end due to voltage drop - sometimes you need extra power feed in along the strip(s) to fix that. This is were 12V can help if the pixels can work down to half that (as seems the case) you can tolerate a lot of voltage drop.

I have a fence where along side the chain of strips I have a thick copper power pair, which taps in at each strip join. That works a treat as the thick copper power cable is low resistance and allows the current to get to the whole strip. The same power supply, which clearly has enough power, could not work the whole chain from just one end as the voltage drop would kill it after about the second strip. Bear in mind, whilst the data has to connect at one end, the power could always connect in the middle of your set up.

Never forget - power ends up as heat and has to go somewhere.

Colour options

There are two main colour options.

• RGB - the simplest type - full colour using Red, Green, and Blue
• RGBW - an extra 4th White LED.

There are some RGBWW with two different shades of white as well, but rare.

the main advantage of RGBW is that the extra white LED is usually very bright (and often available in a specific shades of white), but is also one LED, using less power than combining RGB to make white. Yes you can go overkill and try RGB and W for even more bright and even more power usage.

The general idea is if the strip it to be functional lighting as well as pretty effects, RGBW helps allowing the white to be lighting. You also often want to consider higher density of LEDs in such cases.

Chip type

There are a few chip types, and many odd chips that are compatible. There seem to be some subtle differences in the data sheets but in practice they all work the same way.

• WS2812 is the main one, simple RGB 5V
• SK6812 is another one, typically the order of colours is different in the data sent
• WS2815 is the one that does RGB but using 12V
• There are new WS2815 that are 12V and RGBW

Timing

Rarely an issue, but worth considering - each pixel on a strip takes time. So the maximum update rate of a whole strip depends how many pixels. Each bit is approx 1us long, so each colour is 8, and each RGB is 24us. That means 100 RGB takes 2400us or 2.4ms. RGBW is 4 colours, so takes longer. As you can see, once you have hundreds of pixels the refresh rate can come down and start to be more noticeable. The answer is more separate strips working in parallel if your controller can do that. I'm practice, it is rare for many hundreds of pixels and rare that the refresh rate matters that much. But bear in mind on large installations. 

Duff pixels

One of the reasons to look at the chip type is the WS2815 has a backup data line. The way this works is the data daisy chains from one module to another - any break, or any failed module means the whole of the rest of the strip dies. The WS2815 has a cunning plan - a backup data that goes directly on to the next pixel. The idea is that if a module fails, the next LED picks up the backup line, and delays one pixel, meaning it works and so does the rest of the strip. Only if two adjacent modules fail does the rest of the strip die. This is an excellent innovation, and I definitely recommend it.

Recommendation

The recommendation is simple...

• For density - decide what you need.
• For covering and strip PCB colour - decide what you need.
• Recommend WS2815 RGBW 12V strips - only now available in 2025.

The reasons are simple.

• 12V working is less current, so smaller power supply.
• 12V allows more voltage drop, so longer strips just work.
• WS2815 backup data allows a duff pixel.
• RGBW allows more powerful white at lower power.

(I have some of these latest strips on order).

Magic LEDs

There is a company called Xinglight that make some LEDs that I use. I call them magic LEDs because they are really so useful.

They cost 2p or less each, but they are RGB, so full colour LEDs. Now bear in mind some other single colour LEDs I use on some boards are more like 5p each, these are cheap.

So what makes them magic apart from they price?

• They work from 3.3V (datasheet says 3.5V min, but my tests, room temp, 3.3V just works)
• No need for extra series resistor as normally needed on an LED - no need for any extra component.
• Uses WS2812 serial coding so one can have one or more of these on a single GPIO pin.
• Full colour
• Tiny

So if I want a simple status LED on a board, this is a tiny, 1x1mm component on a single GPIO on the 3.3V supply, and just works. Yes, it is more complex than a simple on/off GPIO, but in some ways that is better is it cannot be on accidentally - it needs the correct code to send the correct sequence to light it up. If this status LED lights up the code is running, meaning it all works, boot loader, signature check on code, code running.

The small ones are 1x1mm, and are really so small. I have used for years on many designs, but it is time for a change.

Why?

These tiny 1x1mm LEDs can snag and come off the PCB very easily.

So what is the alternative? Well, they do a 1.6mm x 1.5mm version and a 2x2mm version.

My current plan is changing all my designs to the SMD1615 (1.6mm x 1.5mm) version.

It has castellated pads, so some chance of solder coming up the sides, and is not that much bigger really.

I usually pack the 1x1mm LEDs at 45 degrees, space at 2x2mm, and can do that both ways, just. The new LEDs can do 2mm spacing straight and neatly. They can fit closer, just, but not both ways if I want to make a grid.

So for single status LED - no brainer, takes about the same space, and easier as a track can run under it.

For a row of LEDs at 2mm spacing, perfect.

Indeed, almost all of my designs work, even the coaster which is 124 LEDs in rings!

Power saving on hot tub, and what not to do

I have posted much on the hot tub. It came with the house, and has been a huge lesson.

Hourly check, some heating, and 13:00 jets

I have also posted how it goes off, and how lately it is a lot better, and I think I finally have the answer.

So this is posted as a word of warning.

Saving power

Something I did early on was put the hot tub on a timer. On during day so I could use it, and on from 2 to 5am to use cheap electricity to top up. The logic of this saving time heating, vs constantly on and allowing thermostat to go on/off, is not clear, but the main saving was that it used cheap electricity at night for a big chunk of the daily usage. So even if heating as long, it was heating cheaper.

Initially this still meant a lot of use, but I have since insulated the internals (lots of pipes with no insulation in there), and moved to a heat pump (less time on, and less power used when on). But still on a timer.

Symtoms

The key problem was that every couple of months it would go off. Start going cloudy, dirty, and getting pH right was almost impossible. No, changing filter alone did not help. So I would empty, and refill, at some cost to reheat a whole tub. Some people were understandably puzzled I had this issue. I was resigned to it being just how it worked.

Obviously I had to add water due to evaporation, ensure chlorine and algicide, and change filter occasionally. But it would still go off after a few months regardless.

What was less obvious is the occasional use by someone that is not me. I would lie there and read, and it would last a few months with no issue. But some times, someone else (relative) would use. On one occasion I berated someone for leaving the tub filthy - so much so I emptied and refilled. It was dirty and cloudy after their one use. I hereby apologise, as I think not their fault.

One clue was Alice, my granddaughter, who uses it when she is here, and usually fine. But on one occasion, after the tub have been a couple months since a refill, she used it, with me as well, and she had a shower first, and I could see she had not dragged in dirt from the garden on her feet, and it was quite a short session. But after use, it was cloudy and dirty. How?

Using a timer

I believe I have solved it, and it is totally silly. Be warned!

The hot tub has water jets, as many do. And these have a lot of pipes (one reason I insulated them all). I don't use the jets when sat reading, but Alice likes them, and so do others.

The hot tub is not stupid, it runs all the water jets for a few minutes every day. In the early days this did surprise us when using it. It seems to do in the afternoon and not sure I can control when. It also has a circulation pump I can control for twice a day for the main tub.

But it has no persistent clock, so the timer meant that twice a day it started as midnight. And was not getting to what it considered afternoon. So did not run the jets, at all, ever!!!

You can imagine the effect, water in lots of pipes, never moving. Even with the chlorine and algicide, and changing filter, this did not help that water stagnating.

Even with no use of the water jets, after a few months it went off, but using the jets would just circulate that all and leave the tub dirty and cloudy. This explained why Alice, and others, using it (with water jets) made it dirty.

Not using a timer

The good news is that now I am not using a timer, it is not going off at all. Yes, I need to change the filter. If I leave it without topping up the chlorine, etc, it may go a tad cloudy, but immediately clear up when I top up (this did not work before). It just says clean, and clear, and nice.

As for cost, well, using heat pump and having battery, and the extra insulation, mean it uses way less power now, and when it does is often from battery that charged from solar, or cheap night electricity. So running 24/7 is nothing like the issue it was when I first started with it.

The house uses way more than average domestic, but even so, several months over the summer we had a negative electricity cost, even with a hot tub on 24/7.

So using a timer on your hot tub may be bad, be warned!

Working with a factory (ESP flasher board)

This is an interesting one for some people I am sure.

We (A&A) do work with (UK) factories for some of our products, and it is interesting, but we get to visit the factory and see that we are happy with how they work, and we provide ATE kit. This is Automated Test Equipment. It will flash code on to the circuit board, and run self tests. In some cases they have a number of Ethernet leads to a test switch as well so it can self test all the Ethernet ports as part of the process.

But as you may know, I get lot of small dev boards from JLC in China. These are great, but they had a few issues with placement and soldering on the main ESP32 module lately.

The solution they propose is that I order some boards with a "functional test". This means I need to make an ATE for them, and send to China. They are going to do the first batch of boards with the functional test for no extra cost, which is nice, and I am going to try and get them to bag and label as well rather than their usual foam and bubblewrap annoyance. Fingers crossed that they can do that and that it is a sane price compared to my doing it. We will see.

The big reason for this is that they don't ship the failed boards, they debug them and fix them, so I don't end up with duff boards for which I don't have the equipment or eyesight to fix. The downside is this normally has a small extra cost.

But this has meant making a Flasher board. A device that can flash code on to one of my dev boards, and report clearly a self test pass or fail. The result is this. It is useful outside of the factory, maybe flashing Tasmota on Shelly boards, or just flashing boards I get in smaller quantities here. It is neater than using command line on my computer and has nice visual feedback on progress.

USB power, and a 6 pin RJ12 or USB-A connector. In this case the 6 pin RJ12 is to a TC2030 connector which plugs in to my boards.

This trick, and a lot of iterations in the code this week, has been to make it as idiot proof as possible.

It flashes from SD card, and can update image files over the internet automatically. It allows up to 10 different flash manifests by button press. It flashes multiple files in different places. It runs the code and waits for ATE: PASS or ATE: FAIL from the device. It provides a loop back link on the TC2030 even so my boards can do a loop back test on the final connection pins as part of their self test.

I have made a video to show the factory - I really hope this is as idiot proof as I hope.

One of those days (Amazon)

I am not looking forward to another lengthy and pointless discussion with Amazon... They really are not fun.

What now?

UPDATE: SOMEONE AT AMAZON FINALLY UNDERSTOOD. PICK ME UP OFF THE FLOOR NOW...

I have listings for things like this...

It is described as "with 3 pin WAGO". The fact it has a WAGO connector is useful, as it is a lot better (in my view) that any sort of plug/socket arrangement or screw terminals, and takes less space as well. It is ideal for this sort of thing (LED strip controller).

Amazon seem to feel that using "WAGO", a trademark name, needs a letter of authorisation.

Thankfully I know someone who is good at pointing me to legislation, and, as I expected "Nothing in the preceding provisions of this section shall be construed as preventing the use of a registered trade mark by any person for the purpose of identifying goods or services as those of the proprietor or a licensee".

So, yes, I can describe the 3 pin WAGO connector as a WAGO connector. I have tweaked to be clear, changing "with 3 pin WAGO" to "with 3 pin WAGO connector", just to be extra clear. And quoted the Trade Marks Act 1994 section 10(6) to Amazon.

I do not hold much hope that this will be a simple "OK, that's fine". But they may yet surprise me. We'll see.

Update: Yep, stock replies, this is going to be a long one.

I've also added this image to the listings :-)

Finally Amazon

It seems only fair to say that Amazon have finally recognised a brand, and so we can now list products once again.

I am not sure we have resolved EAN re-use yet, but at least we can list new products, and have listed a Faikin S21 cable and case.

So well done, even if it took months, and a blog post, to get it done.

Maybe I'll try and get some of our other trademarks added!

Nice neighbourhood

I live in a nice neighbourhood. Really... Well, I thought I did.

After 4 years here this is the first time someone has literally taken a parcel off my doorstep!

Criminal video

To say I am shocked is an understatement.

I never imagined anyone would do this.

I am, however, impressed that the local police has a web page for crime reporting and it seems mostly sane!

Also impressed that they have called me for the raw video so they can try facial recognition.