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Author: bostjan

Fluorescent light and headache. Use LED… err…not so fast

Fluorescent light and headache. Use LED… err…not so fast

When talking about circadian rhythm we already discussed fluorescent lights. They are quite popular in public spaces (shopping centres, stores and also schools). But as stated in the publication – there is a dark side to the fluorescent light.

Fluorescentna cev

More technically inclined readers know that fluorescent light needs a ballast to work. To explain it simply: it’s a box with electronics that take care of voltage to power fluorescent light.

There are two main types of ballast: magnetic and electronic. The difference is a visible one: when you turn on the light – if it flashes, the magnetic ballast is used.

Such ballast is usually used in public spaces since it is cheaper and more reliable. The problem is obvious (visible) – it flashes during the power on.

But according to professor Arnold Wilkins blinking of the fluorescent light (with frequency of 100 to 200 Hz) affects people, especially young. There is an increased risk of anxiety, migraines, headaches and even dyslexia.

Although we save some energy by using fluorescent light we also create some problems.

So we will just use LED light and problem will be solved. Right?

 

Not really. You see – even with LED lighting the manufacturers are using switching power supplies which means there is a high frequency switching of power and we usually (and emphasis on usually) don’t see it.

But some people are affected by it and again – headaches, eye strains etc …

So what is really a solution.

The first one is obvious – test, if you can.

Otherwise – the power for LED does not really need to be switching. It is a direct current device and switching power supplies are used because they save some energy, money and are small, but the power supply can as well be created so the voltage powering the LED is changeless. According to manufacturers, such solutions are more expensive and are not long lasting.

The future will tell, which technology will prevail.

Use legal LED doping to get on the top

Use legal LED doping to get on the top

Jutranje sonce skozi oblake

Interesting article appeard on  lux review. According to the writer – German alpine skiers used glasses with embedded blue LEDs and they illuminated their eyes for 15 minutes. With this procedure the concentration and wakefulness was increased.

And since every hundredth of the second counts in top sports, the coaches pay attention to every detail to improve the result. Obviously they pay attention to not only physical condition, but mental as well.

But, why is such post on the page where we talk about LED lighting?

We already discussed circadian rhythm but let’s take a look how increased alertness affects human psyche. Let’s take a look at the article with title “Circadian Time of Morning Light Administration and Therapeutic Response in Winter Depression” published in a specialised magazine JAMA Psychiary on January 2001.

Authors researched the possibility of therapeutical usage of light as a anti depressive. They used a sample of 42 patients during depression and took samples of melatonin twice a day (in the morning and in the evening) and after 10 to 14 days of 30 minutes of daily usage of strong light. The result showed success with lowering the depression due to change of seasons. The final result also showed that it is better to use additional light in the morning.

Talking about sport and circadian rhythm: German and English experts published a study with the title  The Circadian Rhythm of Core Temperature: Origin and some Implications for Exercise Performance” in Chronobiology International. In the article they used circadian rhythm to lower possibilities of injuries in sports.

To conclude: is the manipulation of circadian rhythm a (currently) allowed doping? And is the protocol of German skiers enough to improve their results and maybe even get the title because of usage of blue light LEDs embedded in the glasses. For only 15 minutes?

Since quite a lot of money is involved in top sport I’m sure there will be extensive researches on the topic.

 

Powering LED strip – solutions that work

Powering LED strip – solutions that work

When buying a LED strip we usually don’t think about power supply. But when we want to use it we find out that 12V power supply is needed and we don’t know how to power the strip. Not to mention we need a switch to turn the strip on and off. So let’s take a look at powering LED strip.

What now?

One of the possibilities is that the switch is already a part of the power supply and we just connect LED strip wires to it. Like you can see it on the image.

 

Stikalo vezano na napajalnik

And since the LED strip needs direct current we need to pay attention to where plus and minus are on the power supply. That’s the reason there is a small + sign on the switch. With this solution you just put the wires in the connectors and use screws to tighten them. Try to pull the wires after you are  done, just to be sure the wires are fixed.

You can now test the strip if it is working and put the whole thing where you need it.

The second possible solution is a power jack at the end of the LED strip, like the one on the image.

power jack

In that case you use a power supply that already has a male part of the power jack. And if needed you can still insert a switch in between jack and power supply. Obviously the switch needs to have proper connectors installed. Again – pay attention to polarity (where is plus and where is a minus connection).

Stikalo, ki ga priklopiš na napajalnik

There is a caveat with this solution – a pull on either side will break the connection so you really need to pay attention to fixing the wires on both ends.

Last but not least: don’t let the power supply hanging. It should be fixed somewhere or at least on the flat surface. If you leave the power supply hanging the tensions in the cable appear and it can break the connection.

How to select power supply to power LED strip

How to select power supply to power LED strip

Some time ago a customer asked us to create a constant source of current to power LED strip.

napajalnik za LED svetila
LED strip power supply

Since the current is used to regulate the lightness of LED strip (with constant voltage) we immediately had some questions regarding power of LEDs on the strip.

 

moder LED trak
blue LED strip

The customer didn’t know what kind of LEDs are on the strip, only that she has 60 diodes per meter and that brightness of 240lm is needed.

After that we came to the conclusion that LED strip with power of 14.4W/m will do and for 4m of such strip, the customer will need 60W power supply.

Since the voltage need for the strip was 12V we need to take the power supply that can handle at least 5A of current, but the customer insisted to use a power supply with maximal current of 1A. Unfortunately – this does not go well with the idea of having brightness of 240lm.

So how do we select a proper power supply?

First you need to check the LED strip data. As said previously: we have 60 LEDs/m and power needed for such LEDs in 14.4W/m. Besides that – the important information is that the strip need 12V of power supply.

We have to pay attention to to the voltage of power supply. It has to be the same (or lower) otherwise we might burn the strip.

Since we selected 4m of strip we can calculate the power needed by multiplying 14.4W/m with 4m and we get needed power: 57.6W so we can look for a power supply which can produce at least 57.6W of power. Although – power supply that can produce power close to the calculated one might get overheated especially if it is enclosed somewhere, so it doesn’t hurt to go higher (but your wallet will be happy if you don’t exaggerate).

And if we are interested in value of current going through the diodes on the strip, we have to divide power with voltage (since the formula for power is voltage multiplied with current) – so 60W divided with 12V and we get 5A.

To conclude: we need power supply with at least 60W of power (or 12V/5A). It doesn’t hurt if higher currents are allowed – you only have to pay attention to the voltage. It needs to be 12V.

 

Selecting power of LED bulbs and other LED lighting

Selecting power of LED bulbs and other LED lighting

Incandescent light bulbs are very old and we got used to selecting them by power.

It was simple: you need really bright room? Select 100W bulb. 60W for smaller rooms etc.

The (mental) list is not really as old as a light bulb, but we got so used to it, that we don’t question it anymore.

But the list of selecting the power changed when the fluorescent lighting arrived on the market. They consumed less power, but gave similar light as light bulbs, so we had to adapt.  And since fluorescent light has its own problems (needing additional electronics, the light needs time to turn to 100% of lighting, not really environmental friendly…) the LED lighting came as a solution to many problems of fluorescent light.

With the arrival of LED lighting the selection of light according to power changed again. The LED bulbs are even more energy efficient, so the power of the bulb was lower for the same brightness.

The best thing would be to create a new mental list of bulb powers that is adapted to LED bulbs especially since LED light comes in all shapes and sizes (panels, strips and of course bulbs).

To make things easier we will concentrate only on the white light and see how we can select them in comparison to regular incandescent light bulbs. We prepared a small infographic with the list of powers of LED bulb in comparison to regular (incandescent) light bulbs.

The numbers on the list are a bit simplified since we use only one value for the brightness although you can see a range when buying a LED bulb. It’s just an estimation, since there are some other factors involved in the brightness of the LED light.

infographics led bulbs selection

We can now select the LED bulb according to our needs.

 

Circadian rhythm, blue light and how it affects sleeping patterns

Circadian rhythm, blue light and how it affects sleeping patterns

What is this  circadian rhythm thing? What it has to do with LED light and why LED light?

The important thing with LED light is that we can change the temperature of the light and affect how much blue light is part of the light.

The circadian rhythm is based on the idea that blue part of the white light gives human body a feeling “it is a day and we have to rise and start working”. A lot of blue part of the white light is produced by electronic devices e.g. computer monitors, smart phones, tablets etc. And if we use such devices during the night and especially before sleep, the blue part of the light shines at us and gives the body information that it is a day and you need to wake up.

So the body wakes, but we wan’t to go to sleep. Unfortunately, quality of sleep is affected and we wake up (in the morning) more tired than when we went to sleep.

To mitigate this effect it is better to read something before sleeping. And by reading I mean paper version of the book, magazine etc. And preferable under the light without blue part of the spectrum – e.g. LED bulb with warm white colour.

The effect of the blue part of the light is used in hospitals so the patients have a proper rhythm of day and night with a usage of LED light.

Development of the LED light also gives us a possibility to select temperature of the light in different parts of building and if we stay in hospital environment we can see that with different temperatures of white light we can separate spaces and select the temperature of the white light in the rooms with patients in a care.

Fluorescentna cev

We can find interesting quote in the above linked article: “Fluorescent lighting may increase UV-related eye diseases by up to 12%”.

So even though fluorescent light is energy efficient it can still cause problems due to colour spectrum of the light it emits.

To be really honest – you need to pay attention to colour spectrum with LED light also.

But since we can replace fluorescent light even with LED strips I really don’t see any reason to use them.

Temperature of the light – How to select it?

Temperature of the light – How to select it?

We are not talking if you get hot under the LED light. We are talking about the temperature of the light.

For example: regular (good old) lightbulb has a temperature of light somewhere between 2700 and 3000K. Which means a bit yellowish glow and this is the light most people are used to.

On the other hand, LED light is usually perceived as cold white light with a temperature of 4000K on. The cold white gives you a feel of more brightness, but some people don’t like the cold look of the light.

basic LED light spectrum

And there is also an issue with blue light. When checking the spectrum of cold white light we can see that blue part of spectrum is dominant.

The problem with blue part of the light is especially visible during the night by the time you want to hit the bed. Why?

Because blue part of the light tells your body: “Oh, it’s morning. Time to wake up.” and you want to go to sleep. Not a great combination.

So – no cold white light in the bedroom.

You can experiment with different LED lights though and see what suits you. You can always use cold white LED in rooms you don’t frequent much, if you find out that the light is a problem.

One of the more interesting takes on light are also stores. What do you want to achieve?

More homey look? Maybe use warm light.

Modern techno feel? Use cold light.

Obviously, you need to talk to designers who can advise you on selection of the light and their brightness. There are also solutions that save energy and turn on (or are more bright) when somebody comes near the display window (at the store). With such setup you can save even more energy for the light and (just a thought) use sensor to start something else too (e.g. video on the screen etc.).

LED strip protection and brightness level

LED strip protection and brightness level

LED strips are being used in different settings: if you need to add light, as a sole light source, just for decoration etc. They come in all shapes and sizes (especially LEDs on the strips). Different versions of white LEDs are used, different colours and you can even get a strip with RGB LEDs.

Another needed information is their power need. They usually need 12V power supply, but you can get strips that need 24V or even 5V.  There are also versions of RGB strips where you select which colour is turned on so you can even play with mixing colours (with some additional hardware).

But since we are talking about light – the most important thing is, how bright we can get a room with LED strip installed. One of the important features is number of LEDs per meter.

My opinion is that 60 LEDs per meter strip gives you the best value for your money.

Next information you need to pay attention to is how that strip was made e.g. is it dust proof and water proof.

For example: rating IP20 (IP: ingress protection) means you don’t get any protection against the elements.  Here is a nice list.

Stripes IP ratings list

Strips can have other ratings e.g. IP65, IP67, IP68 … according to the chart this one has dust protection and with second number the strip is protected against water jets (5), temporary submersion in water (7) or permanent water submersion (8).

And last but not least – power of the LEDs or their size. For example 5050.

list of LEDs

Basically – higher number, more light, but as you can see from the chart. The number is really talking about the size of the LED in millimetres.

Another information is how bright one LED is. By using more LEDs per meter on the strip and larger ones, you get higher brightness. No surprises here.

 

LED store