A friend of mine recently asked me to provide some information on LED STRIP and I thought I’d put a quick blog item together as the subject is likely to be of interest.
“LED STRIP” is a name widely given to a product which is becoming increasingly important. As filament lamps are (thankfully) slowly being resigned to history, CLF (compact fluorescents) took over some years ago but there are a few problems with these lights also.
CFLs are the most abysmal colour but let me explain “colour” first for those raised in art class:
As far as light is concerned there is no such thing as white… white light is a combination of various wavelengths of light – and a commonly used method to minimise the complexity of this is to explain that you can make any colour of light with a combination of RED, GREEN and BLUE. Why not treat yellow as a “primary” colour as with paints? Well that’s because paints are different, mixing two colours makes a DARKER, not LIGHTER colour – it’s called subtraction, suffice it to say that a modern TV can show pretty much any colour – and they ALL come from a combination of red, green and blue. Red+green makes yellow, red+blue makes purple, blue+green makes cyan, all three with care make white – simple as that.
Another way to get “white” light is to generate another colour, let’s say ultra-violet (which is the far end of Blue, generally you can’t see ultraviolet at all well if at all) but use a powder that reacts to that and generates white light – that’s generally called a phosphor and that’s how CFLs work. You have a gas in a tube – you put electricity through it – generates UV – and a white powder on the inside of the tube glows WHITE.
Or kind of – the white you get out of CFLs is AWFUL. What do I mean by WHITE? Well, filament (old-school) lamps generate light by heating a wire. Essentially that generally gives a very bright yellow-ish light – you don’t notice this when you are in it – but try looking through a window from the outside where they have old-school lights – it’s yellow-ish. Then there are “daylight” lamps- these tend to be white with a hint of blue…. recall that in the evening sun, our atmosphere absorbs all but the red end so everything looks orange to red… (unless you live in England in which case the evenings are generally GREY). In the morning there is far more blue in the light – hence the term “daylight” to describe lights which veer to that end of the spectrum. Candles give off a light that is nearer to orange than to white.
Commonly available CFLs come in either “warm” or “daylight” varieties – Chinese manufacturers refer to “degrees Kelvin” to describe the colour – which is about as much use as an ashtray on a motorcycle, to the layman. 6500K is COLD or daylight….5000k is more like a fluorescent tube, 2700k is more toward orange and is your typical incandescent light. A match might be nearer 1700k. Simple – but not a lot of use in the supermarket.
Ok, so filament lights are old-school, inefficient but considered a “nice” colour. Xenon arc lamps as found on up-market cars are cold, clean light and CFLs are just, well, naff, really.
The CFL took off partly because at first, there was this thing about being “green” combined with the fact that everyone DISCOUNTED them – so for a while it was not unusual to see supermarkets selling them for under £1 – certainly we kitted out the entire house and no doubt saved a FORTUNE in electricity. The promise was that they’d last a long time – they do unless you buy them in Spanish supermarkets in which case they’re as likely to blow up or fall to bits on first use.
But now that the grants and discounts are all gone, your humble house light has gone back to to £2-5 quid – so the magic has gone and they’ve still never really solved the boring colour problem.
And so along came LED (light emitting diode). Everyone knows the phrase but what does it actually mean? Well, instead of heating up a wire or exciting a gas, the technology behind LEDS involves getting a piece of silicon to convert electricity directly to light! Not very efficiently I might add – but good enough.
LEDS appeared late last century… I saw my first LED on a Bond movie in a watch – I was so blown away I went straight out and blow all my money on a LED watch. In fact, the basics were sorted as far back as 1907 with the first practical devices appearing in the 1960s. You had a choice of RED, RED or RED.
What you don’t have, you seek and as variations appeared, puke yellow, gross green etc., what we all wanted was BLUE… and then at the very back end of the 20th century after much research we started to see the full range of colours – even purple – and WHITE. LEDs had an issue however, not that efficient, bright enough but as individual LEDS not really bright enough to light up the house.
Remember when electric motors were the poor relatives of the powerful petrol engine? All of that his history now as fans of the TESLA motor car will tell you – and so it is with LEDS – but BEWARE.
The first practical replacements for house lighting came in the form of GU10 and similar clusters of LEDs – maybe 20 to 40 LEDS crammed into a conventional light fitting. FORGET them – utterly useless – what LEDS hate the most is heat. Lamp manufacturers are prone to blindly copy the LED spec sheet claiming countless thousands of hours of life. Well, it’s bollocks. Heat them up, overpower them or any combination and you’re down to weeks or months never mind years. A trip to B&Q will confirm that –check out their overhead LED displays in the lighting section and you’ll find those particular types of light will invariably have several bust lamps amongst their midst.
Next came the new super high power leds – where one or 3 leds would do the job. These are current and are very good (notice the heatsink).. but like all lights follow a model of lighting that’s been around since the candle – the point source. Also these LEDS are STILL not immune to packing in – the light is still concentrated all in one place. Only the long fluorescent tube up to now has broken that mold – but today – it’s all change!
SURFACE MOUNT is a means of compacting electronic components – and you see this in almost all of today’s circuit boards instead of components with leads which need complex assembly we have little rectangle with solder blobs on each end. They are positioned along with solder paste onto a board – the whole lot is put in an oven in which the solder melts and forms connections – and Bob’s your uncle – easy to make, tiny circuits.
LEDS are available as surface-mount blocks and they are CHEAP – and the first use of this came in again GU10 and similar lights, instead of using 40 original LEDS with the associated heat issues and mounting problems, the LEDS could be mounted on a round plate with metal underneath, compacting the size (up to 60 SMT LEDS) and distributing the heat – problem solved. But a BETTER solution is emerging – that of LED STRIPS.
Remember the old 1/4” TAPES before we had compact cassettes. Well, LED STRIP comes on reels like the old tape – but this stuff is made out of a material that supports flexible copper sheet as wiring and surface mount LEDS – typically one LED every couple of centimetres, LED strip typically works on 12v DC (not mains). they are mounted on the strip along with an adhesive backing – and you can cut the strip into combinations of 3 LEDS – i.e. 3, 6, 9, 12 etc. That is because the LEDS work on around 3v (varies) – they mount 3 in series (i.e. head to toe) and use a tiny resistor to stop them blowing up so you can get away with feeding them 12-14 volts You can use strips as long as you like, the only limits being the amount of electricity the copper strip will support without loss over great lengths – and how much current you can get out of a 12v power supply.
Typically you might see a 5metre length of LED strip – powered from a 2 amp 12 volt supply. You can get red, green, yellow, orange, purple, blue, cool white and warm white – there are more variations but this covers the bulk.
But you need to know more in order to make a sensible purchase.
So you can put these strips simply in places that other lights can’t go – in cabinets where there isn’t ROOM for other forms of lighting – or areas where 240v would be unsafe. You can get straight-forward LED strip where the elements are exposed – or you can get a gel-covered version which is WATERPROOF.
You can also get various forms of RSB LED, the simplest has in it’s group of 3 LEDS, a RED, GREEN and BLUE led…. one after another – i.e. R G B R G B etc. There are also TWO sizes of LED which means in a 5 metre roll you might have a total of 300 LEDS – or in the more expensive versions up to 600 LEDS in the same space (the smaller ones are not as bright individually but with twice as many lights they ultimately win on outright brilliance).
That’s great so now you can make any colour including WHITE… erm… no. LEDs that well spaced will NEVER produce white – they produce a disco light with RED, GREEN and BLUE.
What’s needed is a chip with all 3 elements inside right next to each other – and that’s what the latest LED strip has. So now you can have all the colours including WHITE – not only that but with care you can achieve ANY colour temperature of WHITE, from candle all the way to that cold, blue-ish light we call “daylight”.
But now there is something new and exciting – a new form of these chips means they have not only power and ground (and these run on 5v, not 12v and they run individually, not in groups of 3) but also a “serial” input and “serial” output – i.e. 2 more leads… the first in the chain takes an instruction from a controller to tell it what colour and what brilliance to output. Subsequent instructions are simply passed onto the next LED in the chain.
So now it is possible to have a length of LED strip where EACH LIGHT is individually controllable at high speed. Been to an airport recently? Seen the HUGE full colour TV shop displays? Take a close look – each point of light in the very latest ones is a little white chip capable of any colour, any brilliance right up to painfully bright.
This then is the state of the art in LED lighting – strip that can be any colour you like, any brilliance within reason and can even change from one end to the other, producing soft, undulating colour rainbows that are quite hypnotic.
Is it cheap? No. Are current controllers up the mark? No – so this latest form of LED lighting is for the specialist only right now but it’s there – on EBAY if you are up to it.
Stepping back a little, RGB LED strip and single colour strip that WORKS RELIABLY and is inexpensive is there for the taking.
Unless, that is, you are in rip-off Britain and still shop retail for this stuff. Maplins the other day were selling a 5 metre roll plus simple infra-red remote controller – of an older version of the LEDS for a mere £39 – all you need is a power supply which they’ll happily sell you for a tenner no doubt bringing the total cost for 5 metres of lighting to £50.
And what’s wrong with that? Ebay will tell you that. You SHOULD be paying around 1/3rd of that. A single colour strip with power supply for a tenner, a colour strip plus controller for under £20 tops.
There are various buzz-terms around which make things difficult to understand. 5050, 3528 etc… well 5050 LED strip generally has 300 LEDS per 5m length, the smaller 3528 LEDS manage 600 per strip (if stated) – simple as that.
Adhesive – most quote 3M adhesive as if that was a mark of quality. My experience suggests that ANY dirt on the mounting surface or any irregularities – and the stuff won’t stick for long – also warm surfaces… best plan your own mounting method. I generally at least staple the ends (careful you don’t cause a short – this is easier on the gel-coated variety) or find some other way to secure the tape.
Control can be via the controllers they sell = any colour but only 256 combinations so the colour changes are a bit crude - if you expect however a super-smooth transition or brightness change – forget it – with only 256 steps your eyes can tell the change – I’ve no recommendations here as I do my own thing – but if you see a controller offering 16-bit (65k) levels of control – that’ll do the job.
The rest is down to imagination – now you know where to look (EBAY – look up “led strip” – most definitely NOT B&Q) you can have any colour combination – and light anywhere you like. I put a red strip around the doorframe of our front door – looks like a portal off Star Trek – in all the time it’s been up (maybe 2 years) no loss of brilliance – no duff leds. I put white strip on the underside of the roof of the garden hut – 4 years later – still working perfectly – not one single dead light.