Illuminating Africa

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Everything you need to know about CCT or dual-white flexible strips

LED flexible strips have been around for many years now, successfully featured in hundreds and thousands of different applications. They’re long-lasting, flexible and small, and they are available in a range of colours and white temperatures to suit your different needs. Looking for bulkhead lighting for a hotel? 3000K is your temperature of choice. Looking for general lighting? 4000K will do the job. Lighting the work surfaces in a kitchen? A nice cool 6000K will light those surfaces so that you don’t cut your finger. White LEDs are available in a wide range of colour temperatures – the “normal” range being from around 2300K up to 9000K although warmer and cooler tones are available.

But what do you do when you need to change the mood of a room with lighting, say from 4000K during the lunch period to a romantic 2700K in the evening? A quality RGB strip could try and simulate these temperatures but it’s tricky, and the controllers often won’t get it spot on. Besides which, you’ll battle to get an RGB strip which can deliver a decently high CRI.

In cases like this, lighting designers and architects will want very specific temperatures – such as our 2700K and 4000K example and with a decent CRI, such as 80Ra and above. In the past such a requirement would result in two flexible strips being installed, one 2700K strip and one 4000K strip with each being controlled separately.

The LED lighting industry responded by creating what is now commonly called a CCT strip – a strip containing two different temperature chips, usually 3000K and 6000K but in truth these could be any two temperatures. The different whites could be mounted as a sequence of single colour chips – warm white / cool white / warm white / cool white – or as two epiwafers packaged into a single LED, also known as a 2-in-1 chip. Both chip configurations would operate in the same way: a strip with three copper tracks: a common anode, warm white negative and cool white negative. It’s essentially having two coloured strips on one FPC.

Whilst these strips are generally called CCT strips they can also rightfully be called dual-colour strips – since the colours need not be limited to white.

A single colour chip CCT strip
A 2-in-1 CCT strip

Whilst that solves the problem of having to install to different strips in a small location, the controlling of such strips could still be a challenge. LED controller manufacturers responded by creating colours for controlling the two white colours a little more seamlessly. CCT controllers – be they wall controllers or wireless remote controllers – will combine the dimming functionality of two white strips into one controller. By varying the brightness of each of the white chips, you can vary the overall emitted temperature of the strip. Different controllers vary in how they allow you to control the brightness of each of the white temperatures – the one Sunricher example below, has one “wheel” which will allow you to essentially set one temperature on a single brightness continuum from one temperature to the other.

A Sunricher CCT wall controller

 

CCT flexible strips are really uncomplicated – they are in essence two strips in one. The complexity as alwaysis in the controlling of these two strips to achieve the desired outcome, a problem which companies like Sunricher have solved.

Connecting power supplies in parallel or series

Whilst learning about electricity in science class during our formative school years, we were all taught how batteries could be connected in series or parallel, to either increase the voltage or increase the current available. What we learned was relatively simple:

  • Connect two 4V batteries in series and you’d effectively get an 8V battery
  • Connect two 4V batteries in parallel and your “new battery” would effectively last twice as long given the same load

It seems obvious then, that it’s equally possible to wire low voltage switching power supplies in parallel or series, to get the same type of result as with our batteries. The truth is that it’s not so simple and just like adult life out of school, “it’s complicated”.

Connecting switching power supplies in series

When we were learning about electricity with batteries, we took two batteries of the same type and voltage and connected them in series to double the voltage. Connecting switching power supplies in series is possible, but there are some rules to follow. As with our science class lessons with batteries, with power supplies connected in series the output voltage will be the sum of the voltages of the two power supplies.

Voutput = V1 + V2

So as an example, if you require a 36V driver you can connect a 12V and a 24V driver in series.

But what about current ? It does seem intuitive that if you are powering a device which requires 5A that both power supplies connected in series can offer 5A. Building on our example above, this means we should use a 12V 60W power supply and a 24V 120W power supply. In fact, we only need to ensure that if our device draws 5A each driver being connected in series should support at least 5A – they can support a higher current without any issue. Again using our example, we could connect a 12V 120W power supply in series with a 24V 120W power supply to drive our 36V 5A device.

It is important to note, that every power supply has a breakdown voltage – a voltage at which it will fail. When connecting power supplies in series, it is imperative that you ensure that the total output voltage never exceeds the breakdown voltage of any one of the individual power supplies.

Lastly, connect a reverse-based diode between the terminals of each power supply to prevent reverse voltage if one power supply reaches full voltage before the other on power-on.

  • Rule 1 : When connecting power supplies in series, ensure they have the same output current
    Rule 2 : When connecting power supplies in series, place a diode on each power supply between the terminals to prevent reverse voltage. Most Mean Well power supplies already have diodes built-in but make sure …
  • Rule 3 : Never allow the resultant output voltage to exceed the breakdown voltage of any one of the power supplies

LUMUL : Connecting power supplies in series

Here are some examples of possible combinations of power supplies connected in series :

  • 12Vdc@30A power supply in series with a 24Vdc@9A power supply can be used as a 36Vdc@9A power supply.
  • 12Vdc@60A power supply in series with a 5Vdc@37A power supply can be used as a 17Vdc@37A power supply.
  • 9Vdc@20A power supply in series with a 6Vdc@68A power supply can be used as a 15Vdc@20A power supply
  • 5Vdc@20A power supply in series with a 6Vdc@14A power supply and in series with a 7Vdc@25A power supply can be used as an 18Vdc@14A power supply

Connecting switching power supplies in parallel

We’ve established that it’s quite possible and feasible to connect two power supplies in series, with three very important rules to observe, which is really in line with what we learned about connecting batteries in series when we were at school. In those science class lessons, we learned that we can connect batteries in parallel as well. Is this possible with power supplies? The answer is “yes and no” …

Connecting switching power supplies in parallel could cause both power supplies to fail

As a broad guideline rule, you cannot and should not connect two switching power supplies in parallel. There is an exception to this which we’ll get to shortly, but the main reason why most switching power supplies should never be connected in parallel, even if they claim to be same voltage, same make, same current : one power supply will generally bear more load than the other and this will cause that power supply to fail, and then the second power supply will fail due to being overloaded. This is where the exception comes in: some power supplies, but very few, have been designed to support being connected together in parallel. These power supplies have a current sharing function, some of the ranges of Mean Well power supplies which can be safely connected in parallel include: SDR, TDR, PSP, RSP & RST. These power supplies will have a P (LP/CS) terminal which you should connect between the power supplies. Even with these power supplies connected correctly, there are still “issues” such as if the load falls below 10% of the rated load of any one of the power supplies in which case the power supplies start to “play up”.

Even when power supplies are designed to support parallel connection, it’s not perfect and there are issues.

LUMUL : Connecting switching power supplies in parallel

Rule 4 : Do not connect switching power supplies in parallel

The importance of customised flexible strips

LED flexible strips have long established themselves in the lighting industry, used extensively for things like corridor lighting, bulkhead recessed lighting, general accent lighting inside diffused aluminium channels and in signage. What we’re noticing is that so many of our new clients are unaware of something quite simple:

Not all LED flexible strips are the same and not all are suitable for your installation

Quality

There is the obvious difference between a quality LED flexible strip and one which is of poor quality. Some clients are aware of, and insist on high quality LED flexible strips, such as those with a 5 year warranty, and many others seem to think all LED flexible strips are quality. Oh how the latter group are so wrong. There are a few factors which determine whether one LED flexible strip is of a higher quality than another, such as:

  • The quality controls in the factory, including whether they rigidly follow ISO9001 guidelines, and the range of QA tests performed, duration of burn-in tests, water ingress tests, brightness and light disbursement tests, ageing tests, etc;
  • The thickness and width of the copper FPC : the thicker the FPC the better the heat dissipation, but too think will make the strip less flexible;
  • The brand of the LED chipset : Epistar is simply better quality than any Chinese chip such as Hongling and Sanan;
  • The quality of the resistors used;
  • The quality of the 3M backing tape : not all 3M tape used by Chinese factories is made by 3M (i.e. a cheap knock-off) and not all is equally adhesive. Genuine 200MP or 300LSE 3M tape is far sticker than the cheap Chinese imitation 3M tape;
  • The quality of the glue dripping used in IP65 strips : you get epoxy resin and silicone dripping ; silicone is better than epoxy resin, but more expensive. Western-manufactured silicone glue is better quality than Chinese-manufactured silicone glue;
  • The quality of the silicone sleeves in IP67 and IP68 strips;
  • The quality of the SMD placement and soldering process; and
  • The quality of the soldering process when strips are joined together.

On the topic of quality it’s important to note: The higher the quality the higher the cost. This is an unfortunate truth.

Sometimes merely installing a good quality strip is not sufficient

Design specifications

We’ve dealt with quality and you understand some of the things which make one strip a better quality strip than another. But that’s only part of your challenge: you need to purchase and install a flexible strip which is fit-for-purpose – by this we men that you need to install the right product for the job. We’ve already said it: not all flexible strips are equal. Some flexible strips simply won’t be suitable for your installation and if you install the wrong product you or your client will ultimately end up disappointed. Here are some examples of strips which are not fit for purpose:

  • You install a strip designed for 12 hour use per day in a hotel lobby, where it is lit for 24 hours a day. The strip will overheat and will begin to dim quite quickly – much quicker than the claimed L70 lifespan of say 50,000 hours (read: Can an LED luminaire really last 50,000 hours?). Perhaps you needed a strip which has a thick copper FPC, larger chips with higher current-limiting resistors to reduce the current and extend the lumen lifespan.
  • You install a strip which is too bright or too dim for the installation, ruining the lighting effect the architect was after. Maybe you needed a strip with brighter LEDs or maybe more LEDs.
  • You install a strip which shows hot spots, disappointing the architect or client; instead of a regular 60 LED per meter strip perhaps you needed a strip with 180 LEDs per meter with a very small pitch.
  • You install a strip which draws 12 watts per meter but the client required 5 watts per meter but still something relatively bright; perhaps you needed a strip with more LEDs, but lower current draw through the LEDs.
  • You need to mount the strip securely against a rough service, and your off-the-shelf strip with 3M backing tape started to pull away; perhaps it was not genuine 3M tape after all or maybe the wrong type of 3M tape for a rough wall.

The above are a great set of examples to demonstrate how you can so easily disappoint your client by simply purchasing “regular, off-the-shelf” flexible strips from your current supplier.

So what should you do? The best advice we can give is to discuss your installation and client requirements with us. We offer a unique service in South Africa: we will understand your client requirements and provide advice on what type of flexible strip you really require for your installation, and with a relative low MOQ, we will design and manufacture a customised LED flexible strip specific to your installation requirements. It’s OK if you have a preferred supplier other than LUMUL – but ask them for the operating guidelines for their flexible strips, ask them for the full technical specifications, ask them for the L70 lifespan – and remember you don’t have to settle for off-the-shelf – you have the option of getting exactly what you need, at a very affordable price and usually within 3 weeks of payment being received – from LUMUL.

Controlling digital RGB

RGB LED lighting is wonderful. All those different colours are so visually attractive, artistic – but controlling them is an utterly daunting task unless you’ve had some guidance or worked with them before.

In a previous article we wrote about the difference between digital and analogue RGB. Here we’ll focus on how to control digital RGB lights – flexible strips, neon flex, RGB modules or pixel lights. It’s possible to get all of these types of LED lights in what we call digital RGB. With digital RGB you can control an LED matrix, possibly creating your own screen, such as those seen on the side of the field at a sporting event – or perhaps artistic effects on the sides of a building with simple linear lights, maybe artistically lighting up a Ferris wheel – or what about a dance troupe illuminated with digital RGB ?

Some companies talk about pixel chasing RGB, but really, it’s all digital and so we’ll stick with the name digital RGB. Digital RGB lights contain many integrated circuit (IC) chips – one per pixel. The LEDs connected to one IC are what we call a pixel. Sometimes you get one LED per IC – in which case it’s a single LED pixel. In other configurations, you can have multiple LEDs per IC – such as a 3 LED pixel. It’s usually preferred to have as few LEDs per pixel as possible as this allows you to control your LEDs at the most granular level, but it’s not always possible.

Digital RGB flexible strips come in different configurations, such as the two common ones below :
* 5V WS2812B – each LED contains a small embedded IC, and one LED is one pixel
* 12V WS2811 – three LEDs to one IC, meaning three LEDs to one pixel

As an aside, as the voltage of the strip increases the number of LEDs per pixel usually increases too.

Controlling digital RGB is about controlling the ICs which in turn control the LEDs connected to the ICs. A controller will send digital signals to the ICs and the ICs in turn, will control the colour and brightness of one or more LED chips.

The are a number of different ICs used in digital RGB lights and many more digital protocols used by these ICs – it’s important to identify which protocol your lights are using so that you can ensure your controller not only supports the protocol used, but equally is configured correctly for protocol your lights use. Some of the more common protocols include:

WS SeriesTM seriesUCSLPDOther
WS2801TM1803UCS1912LPD1101APA104
WS2803TM1804HUCS6912LPD6803APA102
WS2811LTM1829LUCS2903LPD8803P9813
WS2811HTM1809LUCS1903HLPD8806SK6812
WS2812TM1829HUCS2909HD705
WS2813TM1809HUCS1909LTLS3001
TM1812UCS2912
TM1825HUCS1909H
TM1825LUCS6909
TLS3002UCS1903L
TM1804LUCS2909L

Each protocol is a definition of how the data signals are to be sent so that the controller knows how to send the signals, and the ICs in your light know how to receive and interpret the digital data signals. The protocols differ from each other, even if slightly, which means that mismatching the protocol on the controller and the ICs

The general principle of the different protocols is that the controller would send a sequence of colour+brightness instructions for the different ICs followed by a signal to “activate” ; what this means is that the controller first sends the instructions to your lights’ ICs – which collect the data but do nothing with it, until they get the “activate” instruction. This is what allows thousands of LED pixels to appear to instantaneously change colour.

All the magic happens on the controller. You can get very basic digital RGB controllers or much more capable controllers. You won’t control a Ferris wheel with a basic controller but you could control a simple RGB lighting installation, say recessed bulkhead lights in a ceiling where all you want are some “basic but nice colour effects”. With a basic controller you really have very little control, save for running some pre-built light sequences, changing brightness and maybe the colour of all the lights (like analogue RGB). More complex controllers allow you to define your own lighting scenes using software on a computer, then storing these on the controller (EPROM or SD card) for offline controlling. Other controller allow ou to control the RGB lights in real-time using specialised software. Then there are controllers in the middle of these two: controllers which can accept DMX input or be controlled by remote controls or WiFi Smartphone apps.

LUMUL offers all three types of controllers from basic to highly capable.


Digital RGB controllers only with factory-defined scenes
There are a myriad of digital RGB controllers available which provide a range of factory-defined scenes – single colour scenes, flashing, gradual single colour changing, or a variety of pixel chasing scenes.

LUMUL offers a simple and affordable digital RGB mini-controller. This digital RGB controller which LUMUL supports the WS2811 and WS2812 protocols and offers a range of relatively simple factory-defined scenes which immediately provide some visually appealing effects, particularly suitable for LED flexible strips or LED neon flex. The controller has three buttons, allowing you to scroll through a range of scenes such as chasing scenes, colours changing in a beautiful morphing manner, etc. These controllers have proven to be very reliable with customers.

LUMUL also offers a high-end Sunricher digital RGB controller, which also has factory-defined scenes, but is also controlled through DMX or RF remote control.
… Via DMX you can control individual pixels – each pixel is mapped to one DMX address – meaning the controller can only control 255 pixels – all within one DMX universe.
… Via a matching paired remote control such as SR-2818T8 you can run one of the factory-defined scenes or uniformly change the colours and brightness of the light (like an analogue RGB light).

Digital RGB controllers with offline capabilities
Controllers with an offline capability allow you to craft your own lighting scenes, and store these on the controller – usually on an SD card inserted into the controller. You can then “trigger” your custom scenes, which could be by a DMX signal, or by a remote control or WiFi application. We offer the T1000, T4000 and T8000 digital RGB controllers for which you can create scenes using the LED Edit software program, save the scenes onto an SD card and have those scenes play one after the other, in a loop. The scenes could be as simple as chasing lights, a bit more intricate such as exploding stars, or complex such as a video. Our high-end LED Strip Studio controller range offers the ability to create extremely precise custom scenes, such as lights mapped onto complex shapes such as buildings, and trigger these offline scenes via a DMX input or via live software control (connected via ethernet).

Digital RGB controllers with real-time (live) software control
Our market-leading LED Strip Studio digital RGB controllers from Showtacle in Europe, are proven in controlling large and complex RGB lighting implementations, such as animating the lighting on buildings, lighting TV studios and stage shows and even lighting up dancing troupes! Using the LSS scene design software, the LED lights are mapped – in whatever shape and form they may take, curved, straight, it doesn’t matter. Scenes are then created and triggered via DMX (as per the earlier note) or in real-time from the LSS software program.

Can an LED flexible strip or neon flex really last 50,000 hours?

Many stores and suppliers claim that their LED flexible strips or neon flex will have a lifespan in excess of 30,000 hours – often even 50,000 hours, equating to many years of life. What exactly does this lifespan mean and is it reliable? This article will help you understand what these quoted lifespans actually mean.

There are some basics to understand:

The lifespan of an LED luminaire is not always the same thing as the lifespan of the LED chip
The term lifespan is a misnomer when describing the LED chip
Later in this article we will explain why the lifespan of the LED luminaire is sometimes different to the lifespan of the LED chip. For now, we will focus on the lifespan of the LED chip, as this is actually what that quoted figure, of say 30,000 hours or 50,000 hours is describing. Just knowing a figure of 50,000 hours is actually meaningless since that figure is out of context. If needs to be quoted with what we call an “L rating”. It should read something like L70 at 50,000 hours which would mean that the LED will be at no less than 70% of its original brightness after 50,000 hours.

There is are two international standards called LM-80 and TM-21 which were developed to bring some consistency to how LED lifespan is measured and reported upon. They allow for measurements to be taken over a relatively short time span and extrapolated to predict the brightness of the LEDs over time. It is in effect a standard to measure lumen depreciation (the decrease in brightness over time). Why? By their physical nature, if LEDs are used correctly electronically, they should not fail but will rather simply get dimmer over time until their brightness is no longer useful. These tests and their results don;t tell the full story of the lifespan of a luminaire but are a valuable contribution, because a luminaire often consists of much more than LED chips. Often there are other electronic circuits including power supplies which have their own lifespan factors.

The LM-80 and TM-21 tests and projections give a view on how an LED will perform (brightness and colour) over time at certain temperatures and currents. This is important – since a claim of L70 at 50,000 hours is a little meaningless unless you know at what temperature the figure was measured. The LM-80 tests should be performed at three different temperatures – at 55°, 85° & a temperature selected by the manufacturer, let’s say 25°. So what you really want to know are the different L values at different temperatures so that you can assess the predicted lumen maintenance for your particular installation conditions. The “lifespan” will also always decrease as the operating temperature increases.

Eg: L70 at 50,000 hours at 25° but at 55° L70 drops to 40,000 hours and at 85° L70 drops to 30,000 hours.

Now it’s important to note that no single factory has ever tested a luminaire for 50,000 hours. LM-80 states that tests be performed for no less than 6,000 hours and then TM-21 states that you can project up to a maximum of 5 times the LM-80 test time.

LUMUL ensures that our PVC and Silicone Neon Flex are appropriately tested so that we can accurately give you meaningful L70 lifespan predictions.

Co-ordinating dimming or RGB control across multiple controllers

Controlling the brightness or RGB colour of a large meterage of Neon Flex or flexible strips, or where you have many disparate sections where you need the brightness to be uniformly controlled across all lengths, or the RGB colour controlled uniformly across all sections, you need to give your installation design a bit more thought. When you have multiple sections of neon flex or flexible strips to be controlled (brightness or colour control) you sometimes will need multiple controllers – possibly because your lighting sections are physically far apart or because the current draw of the lengths exceed what a single controller can support.

When you have multiple controllers which you need to synchronise you need *something* to act as the master controlling multiple receiver controllers; that something could be a single remote control which is sending instructions to multiple receiving controllers paired with that single remote control. You could also achieve the same effect by using a smartphone or tablet application (Android or iOS) to control multiple receiving controllers at the same time. The risk faced with this setup, is that one of your receiving controllers receives the wireless signal slightly later than the other controllers or not at all, and your lighting is no longer uniform. Remote controls or WIFI signals are hindered by walls, concrete floors and distance which may also result in unreliable wireless signals being sent to your receiving controllers.The example below shows multiple SR-1009EAWI controllers being controlled by one remote control or smartphone application.

In wireless (RF or WIFI) installations it is possible that one receiving controller can act as the master controller and the others as slaves, where the master controller sequences the other controllers for better synchronisation of brightness and colour.

A far more reliable method of synchronising multiple controllers is by wiring them together. As you can imaging, this implies you are able to wire them together – sometimes not as simple as it sounds because of installation limitations, distances and simple open spaces in-between. In a wired configuration, there must always be a master controller and the rest of the controllers, slaves. There are different protocols which can be used to sequence controllers, the two most common being DMX and DALI. DALI installations are expensive as they require a DALI bus / master control unit whereas DMX installations can be much simpler and cheaper, with options of DMX control panels, DMX control software and even controllers which convert remote control or WIFI signals to DMX signals – much more choice and a lower cost than DALI.

With both DMX and DALI installations, controllers are issued with a unique code (channel number) – with instructions then sent across the wired network of controllers to all of the controllers at the same time. Each controller then recognises the instructions meant for it and executes that instruction – being that to dim to level 3, or to set the RGB colour to a specific colour. With such an installation, it is possible to control each controller separately, sending a different instruction to each controller (controller 1 – dim to level 2 and change colour to pink, controller 2 – dim to level 5 and set your colour to blue, etc) ; equally the same instruction can be sent to all controllers at the same time, achieved either by setting all controllers to channel 1 and only sending instructions to channel 1, or by sending the same instruction to different channels. The former is a much simpler installation whilst the latter requires DMX control units or software. In the diagram below you can see a simple DMX setup where the DMX master is a DMX-enabled control panel (in this case it is wired). In the example below, all the DMX controllers are set to channel 1 – meaning they will be controlled uniformly as instructions are sent to channel 1.

Equally, where there is a DMX-enabled dimmer control panel in this example, you could have a DMX control board or DMX software on a PC.

As with the example above, you could have a remote control or smartphone application controlling the first DMX receiving controller and that one orchestrates the rest. The example below shows SR-2815 being controlled by a remote control and controlling multiple SR-2108EA DMX decoders.

I have shown some of the simpler installation options using RF controllers or wired DMX setups. These are relatively simple to install and get working, and to operate, but as you can imagine, if you want to orchestrate the lighting in a nightclub or on a TV game show set, the installation will become much more complicated and require more planning.

Dimming of LED neon flex and flexible strips

Many people seem unaware that 220V and 12V LED Neon Flex and LED flexible strips can be dimmed. Dimming a 220V incandescent, CFC or halogen lamp was simple : reduce the input AC voltage and the light would dim, generally linearly. As a general rule, LED luminaires can’t be dimmed in this way, and there are two main reasons behind this.

Firstly: LED bulbs or chips operate at what is known as a forward voltage – usually around 4V (give or take). At a lower voltage the LED will be dimmer, at a higher voltage the LED is likely to suffer permanent failure. The LED will not dim linearly since the relationship between the voltage and the amperage of an LED is an exponential curve. As the voltage increases, the amperage increases exponentially which means the brightness increases exponentially. Light dimming must be linear for an acceptable user experience.Equally problematic, is that the LED has a minimum voltage before it “turns on” – meaning it is not possible to use voltage regulation to control the brightness of an LED from 0% to 100% brightness.

Secondly: Most LED luminaires operate at a low voltage, and operate behind a power supply. The power supply will take a 220V AC input and deliver for example, a 12V output. If the input drops to 150V AC the output will remain a constant 12V. So no dimming will occur. Many power supplies have under-voltage protection so that if the input voltage drops below 110V the power supply will not deliver any output voltage. For input voltages under 110V AC there is no output voltage, for input voltages between 110V AC and around 250V AC the output voltage will be 12V and for any input voltage over 250V AC there will again be no output voltage. This is true for most non-dimming switching power supplies, or at least the better quality ones.

So how can you effectively dim an LED?
The only effective way of dimming an LED is via pulse width modulation (PWM) where the input voltage to an LED is turned on and off rapidly, in a sequence. The voltage is either on or off, nothing in-between. If the on and off pulses are equal in time, the LED will be at 50% brightness. If the on pulses are twice as long as the off pulses, the LED will be at 75% brightness.

As can be seen by the diagram above, the sequence of on and off pulses determine the apparent brightness of the LED. I say apparent brightness, since that is how the human eye will perceive it. The PWM pulses are consistent – if they were not consistent in their on and off durations, the LED would appear to flicker.

There are really only two ways of delivering PWM signals to an LED:

a. Via a dimming power supply
b. Via a dimming controller

A dimming power supply is a regular switching power supply with a built-in dimming controller. The dimming power supply will accept a dimming input from a dimming switch of some kind, and convert it to a PWM signal. As an example, a 12V dimming power supply will generate a sequence of 12v / 0V PWM signals. The diagram below shows a dimmable power supply receiving a dimming signal from a dimming switch which will pass a signal to the power supply, which in turn will send a PWM signal to the LED.

A dimming controller is installed in conjunction with a switching power supply, taking for example a 12V input from the power supply, as well as taking input from some form of dimming control or remote control, and output a sequence of 12v / 0V PWM signals.

 


The example above shows a 0-10V or 1-10V dimming controller, receiving an input signal from a dimmer unit, and input from a power supply. The dimming controller sends all voltage to the LED strip light – this will be a PWM signal.

Which LED luminaires cannot be dimmed?
220V luminaires which have a built-in power supply, for example 220V down light bulbs, cannot be dimmed, unless the luminaire was specifically designed to accept a dimming input signal.

Dimming protocols
There are a number of dimming protocols and it is essential that you plan well when deciding which protocol to use: 0-10V, 1-10V, Triac, DALI, 10V PWM, resistance, DMX. You need to match the protocol of the dimmer unit (the dimmer switch unit in the wall for example) with the protocol of the dimming power supply or the dimming controller. As an example, you cannot use a DALI dimmer unit with a Triac dimming controller. Triac and resistance dimmers are possibly the simplest to understand and install.

A DALI dimmer unit will send its dimming signal to a DALI control bus which in turn will send its signal to a DALI-compliant dimming controller or a DALI-compliant dimming power supply. As you can see in the diagram below, a DALI system is complex and is generally used in large, commercial installations where entire buildings need to have their lighting controlled.

LUMUL sells the Mean Well ELG range of dimming power supplies, which support :
i. 3-in-1 dimming (0-10V, 10V PWM and resistance)
ii. DALI dimming
iii. Smart timer dimming

LUMUL also sells a range of controllers, both RGB and single colour dimming controllers. We offer controllers which accept DMX inputs, which act as DMX masters, accept RF inputs from remote controls, inputs from SmartPhone or tablet applications, which accept DALI inputs but equally, which generate DALI signals, and many which dim LEDs directly via a PWM signal.

Call us on 083-349-8453 or email us on enquiries@lumul.co.za to discuss how best to dim your LED installation.

Technical drivers of quality of Neon Flex

Given you’re on our Neon Flex website reading this article, the odds are good that you’re either in the industry or looking to purchase Neon Flex. No doubt you’ve looked and found a few neon flex offerings available, and perhaps you’ve been left wondering what differentiates the different offerings apart from price. In this article, we’ll explore some of the important considerations you should make to help you decide on the product best suited to your needs.

At LUMUL we only focus on quality products – if you ask us to source a cheap and cheerful product for you, we’d politely decline, so we like to feel like we’re qualified to provide you with insights on quality.

LED Chip Type

It’s important to know what make of chip is inside your Neon Flex.

Did you know that there are really two types of LED Neon Flex available: DIP and SMD LED flex? The differences between the two are stark. You can guess that one uses DIP LEDs, those “old fashioned” LED bulbs, and the other uses SMD LED chips. DIP LEDs are old technology. Although invented in 1927 they entered mainstream use in the 1960’s and have not developed a heck of a lot since then. Fundamentally they remain the same today as in the 1960’s apart from possibly being smaller and brighter. SMD LEDs are a much more recent technology and as such they are much more efficient than DIP LEDs. Not only are they more efficient than DIPs but they last longer and generally have better CRI. LUMUL LED Neon Flex is always made with modern SMD LED chips.

But not all SMD LEDs are equal. there are a variety of SMD chips in the market, generally noted as different size chips. In actual fact it’s the “packaging” that’s a different size, that typically white body with a yellowish lens. It’s not always true that the larger the chip the brighter the chip or better the chip.

Different SMD LEDs consume different amounts of power, and different SMD LEDs emit a different amount of light. You cannot assume either based on the size, you need to look at the chip spec from the packager, as they can use different internals (epiwafers) and different phosphorous mixtures, which would affect the brightness and the power consumption. One ideally wants bright LEDs drawing little power.

If the above were not complex enough, you need to be very conscious of heat. Heat is the enemy of an LED and reduces the lifespan of the LED, basically reducing the brightness, so it’s essential that heat is dissipated away from the LED as effectively as possible. Newer SMD LED chips, like the 2835 chip, have better heat sinks and thus draw heat away more effectively than say on a 3528 chip. In terms of L*B they are the same size, however the 2835 can be brighter and far more efficient (lm/W). LUMUL LED Neon Flex is made from 2835 SMD chips for our single colour ranges, and SMD 5050 chips for the RGB offering.

The chip manufacturer is very important. There are quality chips and inferior chips, and the difference is stark. Quality chip manufacturers are able to manufacture chips which retain their brightness for years, can achieve high brightness and which offer great efficiency – names like Epistar, Bridgelux, Cree, Samsung, Nichia, Philips. Then there are many Chinese chip manufacturers whose LED chips are simply poor: poor brightness, poor colour accuracy, poor efficiency and importantly, high lumen decay. LUMUL Neon Flex contains Epistar SMD chips – the same brand used in all your LG LED televisions.

There is a real science behind mixing the phosphorous for the different colours of SMD LED chips. The light colour is a combination of the epiwafer and the phosphorous mix. Some companies will only use a high quality phospherous mixture, mixed by top chemists, whilst others use a cheap mixture. The difference is stark. the poor quality phospherous will result in poor CRI and inconsistent colour. LUMUL LED Neon Flex has a CRI of over 80Ra for our white colour Neon.

PVC Jackets

It is important to choose a Neon Flex with a PVC which is UV-resistant, especially here in South Africa with our harsh sun. It is important to remember that no Neon Flex will be impervious to the radiation from our sun, so all will over time start to lose their colour and perish. Good quality Neon Flex will last much longer in the sun as it will contain UV-inhibitors. the coloured jackets contain a dye, which the factory engineers mix. Skilled engineers will be able to mix colours consistently, so that your order of red today will be the same colour as your order of red in a year or two. Colour consistency is easier to attain with coloured LEDs with a milky white jacket neon flex than a coloured jacket neon flex. LUMUL LED Neon Flex always contains UV-inhibitors.

Flexible Strip

Inside each SMD Neon flex is an LED flexible strip. Heat dissipation again becomes important, given you have a strip of SMD chips on a copper FPC and the heat needs to go somewhere. The thickness of the copper FPC is important as the thicker it is the better the heat dissipation. Many Neon Flex manufacturers use a thin FPC as it’s cheaper,. LUMUL LED Neon Flex contains a minimum of 3oz copper FPC.

Running through the length of Neon Flex are two to four wires for power connection. Cheaper Neon Flex will contain a thinner, lower grade copper wire, and sometimes not even copper. Copper conducts electricity better than most other metal wires used, and the thicker the copper the better in terms of voltage drop. LUMUL LED Neon Flex contains copper wire.

Digital or analogue RGB?

Being able to control the colour of your Neon Flex to your customers’ very specific branding requirement can be the deciding factor in you getting the commission. Single colour Neon Flex comes in pre-determined colours: cold white, warm white, red, green, blue, yellow, orange, pink and purple. These colours are determined by the jacket colour (made from coloured PVC pellets) or LED colour and whilst these colours can be configured for a customer, it can only be done on large custom orders. It is also no guarantee that you will get your exact colour since mixing a custom PVC colour is more art than science, whilst the temperature of the LED chip colour is slightly reduced by the milky white PVC jacket.

With RGB Neon Flex you are generally able to produce exact colours which your customers demand.

LUMUL produce two ranges of RGB Neon Flex: analogue RGB (often referred to as 7 colour RGB) and digital RGB (often referred to as 16 million colour RGB). The difference between these two may confuse some people, and the terms 7 colour and 16 million colour are quite misleading.

Analogue RGB

LUMUL analogue RGB Neon Flex is made with Epistar tri-colour 5050 SMD chips. The chip packaging is square measuring 5mm by 5mm, and is quite special in that it contains three Epistar epi-wafers inside, one red, one green and one blue. Analogue RGB Neon Flex is recognisable by using connector pins with 4 pins : Red, Green, Blue and a common anode. The 5050 chips are wired together in a way that all the green LEDs are controlled together as one, all red as one and all blue as one. The result is that you can turn all green LEDs on at one time, all red on at one time and all blue on at one time. You can already guess that the Neon Flex can easily be red, green or blue, and by lighting a combination of these colours, can also be cyan, magenta, yellow or white.

Red+Green = Yellow

Green+Blue=Cyan

Red+Green+Blue=White

Red+Blue=Magenta

And this is where the term “7 colour RGB” comes from.

The cheaper RGB controllers with built-in programs often allow one of these 7 colours to be lit, sometimes with patterns and effects. What many people don’t realise is that these 7 colours are not a hard restriction. The current flowing through each colour chip can determine its brightness, and through that, a whole range of Neon Flex colours can be unlocked. To achieve these ranges of colours all you need to do is use a more sophisticated RGB controller. LUMUL offers a range of controllers (12V and 220V) which are able to intricately control the 5050 tri-colour chips unlocking a palette of millions of colours. In practise, the controllers use PWM to dim each colour rather than limiting the current, since LEDs actually stop responding when the current flow reaches a particular low threshold.

Summary: With analogue RGB Neon Flex you set a single colour for the entire length of Neon Flex, and using the right controller you can achieve almost any colour you require.

Digital RGB

Digital RGB gets its name because it contains IC (integrated circuit) chips for controlling the LED chips. Digital RGB is sometimes referred to as pixel-chasing because individual “pixels” on the RGB Neon Flex can be controlled through controllers and software. The colour and brightness of individual pixels can be controlled along the Neon Flex length creating stunning effects. The “pixels” can be either 1 LED or 3 LEDs together; LUMUL digital Neon Flex contains 3 LED chips per pixel. Single LED pixels are more expensive to produce and consist of a WS2811 controller per chip, either mounted on the FPC or mounted within the 5050 chip package (WS2812B for example).

Digital RGB is never available in 220V – only 24V, 12V or 5V which means only shorter runs are possible, generally up to a maximum of 10m.

Digital RGB Neon Flex is generally recognisable by the connector pins containing three pins: positive, negative and data. It is controlled through digital data signals which instruct each pixel. A stream of data is published to the Neon Flex followed by an instruction to “activate the stream”. For WS2801 IC chips, there would be 4 pins, for positive, negative, data and clock.

Controlling a data stream is actually quite simple and can even be done through a Raspberry PI or Arduino board, or equally using a more professional SPI controller such as those sold by LUMUL, even a DMX SPI controller. LUMUL offers  range of controllers for our 12V digital RGB Neon Flex.

Summary: With digital RGB Neon Flex you can control the colour and brightness of individual pixels, which are either 1 LED or 3 LEDs.

Digital RGB Neon Flex

Digital RGB Neon Flex

 

Protecting against electrical spikes and surges

It’s so important to realise that our electrical supply from Eskom, often distributed by the local municipalities, is not always “clean”. There are two problems we all need to accept may happen from time to time: electrical spikes, or surges in voltage, and polarity reversal. Both of these can have a catastrophic effect on electronics.

 

Polarity reversal is less common than electrical spikes but certainly happens, and when it does it can cause major damage to equipment designed to receive a particular polarity. Our view is that polarity reversal should not damage Neon Flex, neither 12V nor 220V.

 

Electrical spikes or surges are where a short burst of higher-than-normal voltage is delivered by Eskom or a municipality. Instead of being supplied between 220V and 230V AC – an accepted voltage range which most high voltage electrical items should be able to safely tolerate – you are supplied much more. Many electrical goods are not protected against power surges, for various reasons, whilst some are well-protected. Good power supplies, such as Meanwell power supplies, have over-voltage and under-current protection where the power supply will cut out if too much voltage is supplied, or too little current available, to prevent damage to the power supply and downstream electronics. If you had 12V Neon Flex connected to one of these power supplies, your Neon Flex would be protected from an electrical surge. 220V Neon Flex receives its power directly from the 220V mains, operating internally at 220V DC – with a small rectifier converting 220V AC to 220V DC. If the electricity supply surges to say 270V that entire voltage is transferred to the Neon Flex circuitry, which cannot handle more than around 225V to 230V.

 

Some insurance companies will cover damage by electrical surges or polarity reversal, and victims of such damage can lodge claims with Eskom for the damage, however it seems prudent to try protect against this rather than deal with the damage, in particular when one considers a large Neon Flex installation which may need to be re-installed. The cost and hassle factor might be high.

 

At LUMUL we strongly recommend customers purchase and install a power conditioner when installing 220V Neon Flex. There are various types of power conditioners available, electrical or servo switching, so it is important to ensure you install a power conditioner which can extremely quickly stop a spike over 225V / 230V. The best type of power conditioner will be a UPS, since it quite physically separates the input voltage from the output voltage via a battery and will always ensure a stable, constant clean voltage.

Generally 220V Neon Flex won’t draw much current – a 100m length will draw at most 6.5A which most consumer-grade power conditioners could safely handle.