UK theme parks from another point of view!

 
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TheOutpatient
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LED lighting

Sun Oct 20, 2013 5:51 pm

I lifted to the bottom of my optical mouse up a minute ago
and what I can see is that the LED is flickering very fast. The light looks "digital" so it made me wonder about LED lighting in the park(s). I don't know if this happens with every LED lamp but it happens with my star cloth when it in slow fade more.

I've seen you can now get LED profile spots - so the whole light market is probably having a bash at it. I'm not 100% sure but I think because of the way LEDs are dimmed -using pulse width modulation-, that causes the flicker - I don't know if the more expensive lanterns are better?

Sub Terra has a lot of LEDs and for the most part I think looks pretty good. The light that fades in and out INSIDE the egg goes in steps but it doesn't really offend me, -however- I can see that with my star cloth in slow fade mode, the fading is much smoother,
But like I said I have no issue with it including because LEDs use waaaay less power than halogen/similar lights. The strobes there are also LED so good on AT. I think the environment is a good priority to have.

I guess one way to make LED cans fade more softly is to use an LCD or mesh or a rolling (darkening) gel on front of it but that does waste a lot of light energy.

What do you think about LED lights?
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PeteB
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Re: LED lighting

Mon Oct 21, 2013 9:58 pm

In terms of production lighting - i.e. professional products, LED lighting is all the rage now and not many tungsten or halogen lamps are used. We use nearly all LED lights at the company I work for and they can be dimmed, colour mixed etc to your hearts content and don't flicker.

LED's flicker because diodes only allow current to pass in one direction, which means that they need DC voltage. In the UK, AC voltage changes direction 50 times per second (50Hz) which means when LED's are hooked up without additional circuitry you effectively only get 25 "flashes" from the diode. This is only just noticeable so they can get away with making LED lights like this.  The problem is made worse though when you try to dim them with pulse width modulation, which is why you see a more noticeable and "stepped" type flicker as the LED fades down.

LED's in star clothes tend to be basically Christmas tree lights. Which are cheap. Unless you buy a really expensive star cloth.

In more expense lighting products (like pars, profiles, spots, washes, moving heads), the additional circuitry will include a DC Rectifier which inverts the reversing part of AC current and so you get your 50Hz back. They may also be dimmed by voltage rather than pulse width to get smoother dimming.

As for your mouse however, it's likely that the LED flickers because it is sending out a timed signal, which is then bounced back off the surface and picked up by something like an optotransister or optoisolater. If you changed the LED in your TV remote to one which emits visible light (as opposed to infrared) then you would see a similar "pulse code" being sent out when you press the buttons.
Last edited by PeteB on Mon Oct 21, 2013 10:01 pm, edited 1 time in total.
 
Wildboy
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Re: LED lighting

Tue Oct 22, 2013 9:32 am

I work for an energy company and I spend most of my time persuading people to change from halogen GU10s to LED and most people have no clue yet as to what an LED is or the benefits of using them yet they will undoubtedly be the main type of lighting in the home within the next few years. They enable me to cycle to work with a bike light that's brighter than a car headlight and smaller than a conventional lamp. Even streetlamps are now being fitted with LED lamps. You can even control the mood and colour of lighting in the home by phone app if you want to.
I use LED in my disco lighting equipment for my LED screen, uplighting and some of my moving heads and I initially had an aversion to them but the benefits make them a no brainer.

All we need is greater awareness of the benefits and then the cost will come down dramatically.
Last edited by Wildboy on Tue Oct 22, 2013 11:08 am, edited 1 time in total.
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TheOutpatient
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Re: LED lighting

Tue Oct 22, 2013 9:47 am

I really thought they would be more popular by now. They use like 2 or 5 watts (compared to normal bulbs: 100 watts and compact fluorescent which use 11 watts)
The other big benefit is they bulbs last decades. I bought  LED golf ball for my bedroom in 2010 I think it was - its still going strong.
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Vladimir Bobinski
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Re: LED lighting

Tue Oct 22, 2013 2:34 pm

LED lighting has a lot of applications, the main delay has been the cost along with the constant improvements in efficiency, colour temperate replication, etc.  The Seat Leon was the first car I believe to have complete LED lighting with no type of discharge bulb being used. 

Another recent application was the Queensway/Chad's tunnel refurbishment in Birmingham that has replaced all it's lighting, another benefit of LED is that it's car more consistent and uniform, creating a consistent level of intensity.

However, it's not a complete replacement for traditional HID.  Concerts for example, the main place LED has come in, well first it was the video aspect which has reduced the size of and weight of panels, meaning it's easier to put a bigger show on without out more trucks, more power, more weight allowance etc, along with maintaining a great pixel spacing & resolution for audiences.  With lighting, they are mainly being used as alternative to stage washes.  Washes don't need to be focused, or to controlled.  But they need to change quickly and be controllable, which they are. 

What they haven't replaced is traditional intelligent spot lights, you can't put a sharp edge on traditional lighting, make it pencil thin or suddenly make it a fat star effect.  Just an example, Muse's recent arena tour.

http://www.eventindustrynews.co.uk/wp-c ... C_0149.jpg

The bottom lighting providing the red wash are all Mac Aura LED Fixtures, everything coming are traditional luminaires, MAC Viper's I believe, which are recent new product.

I'm not familiar with the exact specs or LED/HID lumiaries, the power used, the colour temperature ranges, the lumens, etc.  But I know in most cases, IE architectual lighting among other applications, there is a strong case for LED.
 
Tryst
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Re: LED lighting

Tue Oct 22, 2013 3:55 pm

Cheap, mains operated stuff may flicker at 50Hz, but that's typically only found on cheap'n'nasty stuff where they've not bothered to either rectify, or smooth the rectified current.

On LED lighting with dims and fades, the PWM frequency has a big role in perceived flicker. The higher the frequency, the less flicker you will notice.

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