LED lighting products are relatively new for the commercial market and as with any new product, they have to deal with doubt and negative comments from consumers’ side. There just is a lot of false information about LED lights that creates many misconceptions about them. So here are the greatest myths about LED lamps and also some facts that show how untrue these myths are.
By Arthur Smith
LED lighting lasts forever
It’s often speculated that LED bulbs last forever, and, if they are used correctly, you will never have to change them. But that is not quite true. Although LED bulbs really don’t burn out as quickly as fluorescent lamps or flood lights, they still degrade and dim over time. Usually, the diodes will become dimmer and less bright when they near the end of their lifespan. However, since the average life of a LED bulbs is about 50,000 hours of burn time, this will be a very slow process and you will still be able to use your LEDs a lot longer than other types of bulbs. And if you want to prolong the lifespan of LED bulb even further, avoid overheating them and use only appropriate light fixtures and dimmers with your LEDs, and you should be able to get away with using a single LED bulb for about two decades.
LEDs have low carbon footprint, because they are energy efficient
Many people think that LED lighting has very low or no carbon footprint at all. Actually if we compare the carbon footprint of LED bulbs and fluorescent or halogen bulbs, which are the main rivals for LEDs, then LED bulbs really do emit much less carbon dioxide, simply because they produce light by using less electricity. The issue, however, is that smaller electricity consumption and lower energy costs urge people to use more light, so ultimately the amount of CO2 emissions remain about the same. Add to that the fact, that the production of LED lamps haven’t become as efficient as it should be yet, so it also creates carbon dioxide as well as other pollution, and you can say that, although LEDs do have lower carbon footprint, it is nowhere near an eco-friendly level.
LED bulbs emit too much blue lighting
Another great misconception is that LED bulbs emit too much blue light. But that is not true. When LED bulbs first showed up on the commercial market, they did emit only blue light, so this is probably where this myth came from. But nowadays, manufacturers have come up with techniques that enable them to convert the blue-light emitting diodes to give out white or yellow-white light. So you can buy LEDs that won’t emit virtually any blue light, however, you can also sill buy cool-white LED bulbs, that will have blue illumination. Just check the color temperature of the bulbs when you are choosing your next LEDs, and you should be able to avoid having bulbs, that give out too much blue light.
All LED bulbs are the same, so I can just buy the cheapest ones
Very common myth about LED lighting is that all the LED bulbs have the same features and quality, so you can just buy the cheapest bulbs and call it a day. The truth is that there are many different LED bulb manufacturers and they are quite different from each other, which means that the quality of their bulbs differ to, therefore consumers always should pay attention to what they are buying. I would recommend to buy LED bulbs only from reputable companies that offer guarantees with their product. These companies invest in research and testing, to ensure highest quality for their products. Which means that you will have the best bulbs that you can have for the money you spend on them.
LED lamps might be efficient, but they are too expensive
Lastly, another myth that discourage many consumers from buying LED bulbs is that they are just way too expensive to be a valid light bulb alternative. It is true that LED bulbs are more expensive than traditional incandescent bulbs or halogen bulbs, but they will pay back in no-time. Mainly because LED bulbs not only lasts for a long time, but consumers will also be able to save a lot of money on electricity using LEDs as well. Switching to LED lights really requires for some investment, but it will be a lot cheaper in a long run.
Many people just assume that rumors, which they have heard somewhere about LED lighting, are true, so they don’t buy LED bulbs and opt for less efficient incandescent, halogen or fluorescent bulbs. But that is the wrong choice, because, even if you do your own research before switching to LEDs full time, you will only find more reasons to convert to LED lights and forget about all other options.
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Some funny notes on LEDs vs lighing… though I partially parted my ways with “bulbs” and “fixtures”.
1) if one designs some “custom” thing for self, just derate your LEDs to about 50% of their max current and ensure proper heatsinking. Then they will last “almost forever”, its mostly heat that causes LEDs to lose brightnes. “Bulb” design is crappy in this regard – bulbs were never meant to sink heat, to begin with. Interestingly, human eye perception of brightness is non-linear, as well as amount of light emitted by LED vs current. So if you chop half of current out, you’ll often barely notice any difference. Overall it would look like 80-90% of brightness, despite cutting power consumption by half. Pre-made bulbs try to extract all juice out of mediocre LEDs to save few pennies (big deal in mass production) – and crappy at heat sinking. So their life isn’t infinite, sure. If you design lighting for self, few pennies are far less of an issue – so one can do it much better than that. Including LED installations that last more or less “forever”.
2) As concrete example, only mount LED stripes in aluminum rail profile designed for these purposes. It both makes whole thing look reasonable, protects eyes from bright light spots sources that are hazardous to stare otherwise and provides good heat sink. Sure, aluminum rails targeting LED lighting could cost something, but overall worth of it. It solves several challenges at once. Compared to bulbs, this approach gives way more options on how to do lighting. As example, you could abandon hanging fixtures and rather put barely noticeable unobtrusive aluminum rails over perimeter of the room, so lighting is truly omnidirectional and unobtrusive. Sure, it is a big departure from “historic” ways. LEDs opened many new ways on how we do lighting, that were not feasible previously. Bulbs aren’t best option to use LEDs, to begin with.
3) For long-term general lighting LEDs should be 2700 to 4000K (“warm white” to “neutral white”). As Swagatam told, modern white leds work like this: powerful blue led chip emits blue light. Part of this light converted by phosphors into red and blue light, so overall it looks white. Yet not all LEDs are created equal! Some convert more blue light into red/green and some do less. So cheapest, blueish-color LEDs aka “cold white” (color temperature 5000K or more) emit way too much blue. It isn’t a major problem for short term. However, human eye got very weak sensitivity to blue, and therefore would underestimate strength of cold-white LEDs. Long-term exposure to conditions like this puts you at risk of burning retina – eye protective functions do not kick in to extent they are really meant to. That’s one of reasons why “cold white” LEDs are cheaper. When manufacturing LEDs, result could be “unknown” before process finished. When process is complete, LEDs are sorted/binned, “more suitable” bins are priced higher – for a reason. Saving pennies is at your own peril! But “cold white” could be ok for flashlights/cycle lights/etc, low-intensity lights, rarely used lights and so on. On positive side, cold-white LEDs tend to be a bit better at energy efficiency. This advantage partially offset by low sensitivity of eye to blue, but if one wants long-lasting and bright flashlight, “cold white” generally beats “warm white” a bit in terms of brightness vs power consumption assuming other conditions are equal. However long-term general lighting comes with different priorities in mind, including long-term exposure eyes safety.
4) About power efficiency… modern LEDs are good at it. When I parted my ways with incadescent lamps, electricity bills got cut by 30%!!! Quite a win for wallet and planet. Sure, one could afford more light this way. But at some point, it just too bright or you do not see improvement anymore. So overall it quite an improvement in energy consumption. Its possible to push further by installing, say, motion sensors. LEDs do not mind frequent power cycling, unlike CCFLs and incadescent – so switching them on and off as needed is an option. Doing so with incadescent lamps and CCFLs shortens their life a lot. LEDs are fine with it.
5) Even if your LEDs would last “forever” – what about power supply? After all, if your power supply fails, whole thing is out. Yet, derating trick works as well: if one uses power supply at 50% of its rated power or less, it would last far longer than if you go for maximum rated power. This consideration makes sense for LED stripes and somesuch, that are often use mere 12V or 24V DC. Note that halogen lamp transformers aren’t suitable for LED stripes “as is” since they output 12V as AC – lacking rectifier and filter parts. But if someone wants to save few $ by using skill and knowledge, its possible to convert halogen lamp 12V transformer into LED strip 12V transformer – by merely adding diodes bridge and (optionally) filter capacitor(s) to eliminate that pesky 2x(50 or 60Hz) blinking. Things to consider would be: bridge diodes should be of “fast” type, e.g. Schottky diodes used in SMPS (electronic transformer is kind of SMPS, running >20kHz so usual diodes wouldn’t do), also reasonable heatsink needed. If one goes for filter capacitors, keep in mind that 12V of halogen lamp transformer is 12V AC, its “effective” value. Peak value is almost 17V and with filter capacitor rectified voltage would get close to this point, giving a chance of excessive current through led stripe, possibly shortening its life. Yet one can drop couple of “excessive” volts by using relatively long and thin wires from power supply to LED stripe, for example. It slightly reduces efficiency though.
Thank you John, you’ve been providing some invaluable information through your comments, please keep up the good work
Yes sir it is a IC 555/4017 chaser circuit. The load of each channel is 1000w. Yes it is AC 220 V Bulb.
since it is 1000 watt load, your triacs might need more gate current, may be upto 30mA, you can put transistor stage in between IC output and triac gate to increase current.
use the following configuration with each IC otput
https://2.bp.blogspot.com/-SNrJNtauf1E/T5_bMrg8duI/AAAAAAAABOk/AK8hXbJP6bA/s1600/delay+timer+improved+circuit.png
ignore the 1000uF capacitor and the switch remove them, replace 2M2 with 10K, remove the LEd/resistor, and connect the collector of the PNP with the triac gate via a 1K resistor
Sir Please help to short out my problem, I had a 3 step running chaser fitted with 3 nos of 12 v relay. Sir now I have replace the relay by bt136 but now the problem is that 100k pot is not working. I have also tried 250k and 470k pot but not able to control the speed. But when I use relay then 100k pot is working. So please help me which pot will be suitable to control the speed if i use triac bt136.
Rajesh, please show me the schematic, is it a IC 555/4017 chaser circuit? and what is the load? is it AC 220V bulbs
sir i have connected 8 leds is series . 4 strings so 32 leds but too leds are getting heated
1) is led resistor is required for led driver circuit
2) the output voltage is from 23 to 36
yes resistor will be necessary, the voltage should be preferably constant.
if output voltage is not constant then use an average value in the formula
sir i am your regular reader . today i am facing a big problem i have got 50 led driver circuit of 8 to 12 watt with voltage 24 to 36 and 270mA of current . i want to drive 5630 smd led warm white its fv is 3.3 to 3.6 with 150mA of current . my question is how i should wire the leds in series of 3.3*8=24.6 . an i drive 2 series because of driver current is 270mA
Sameer, the input current is not relevant and can be ignored.
you can divide the 24V with 3.3V for getting the number of LEDs on each string
therefore 24/3.3 = 7 approximately.
Now you may calculate a series resistor for the above string using the following formula:
supply – total LED FWD / LED current
24 – (7×3.3) / 0.15 = 6 Ohm
wattage = 24 – (7×3.3) x 0.15 = 0.135 watts or 1/4 watt