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Patrick Francis
Frequent User
Username: jackpot

Post Number: 94
Registered: 11-2016
Posted on Thursday, 27 April, 2017 - 03:15 am:   Edit PostDelete PostView Post/Check IP

Hi All
I just thought I would share an intresting discovery of mine.
I have been playing around with LED substitute bulbs for my various cars including the Shadow 1.
Although I have managed to get very close to ideal, I always thought there was something lacking in the clarity of the dials with LEDs.

I have just been renovating my apartment, and my wife has quite ethnic taste, and so chose quite an elaborate hand constructed lamp which is metal with cut out designs.

I installed it, and chose a warm (2700K) LED bulb for it to give a comfortable glow. When I switched it on, she looked at it and said "this isn't the effect that I wanted at all, it throws no interesting shadows".

So I found an incandescent bulb and installed it: Bingo! the whole room had the shadow of the lamp design!

LEDs do not cast shadows?? Is this why incadescents maybe give a sharper light and effect.

I have not experimented any further, but would be interested to hear if anyone has had the same experience?
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Graham Watson
Experienced User
Username: graham508

Post Number: 44
Registered: 3-2016
Posted on Thursday, 27 April, 2017 - 03:50 am:   Edit PostDelete PostView Post/Check IP

Hi Patrick,
It may be the beam pattern of the particular LED bulb you used. I don't know a lot about LED vs incandescent but I do know that there are various degrees of beam patterns with LED bulbs. Just a thought.
I am using LEDs for the semaphores, dash, etc. for my MKVI.
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John Beech
Grand Master
Username: jbeech

Post Number: 361
Registered: 10-2016
Posted on Friday, 28 April, 2017 - 02:13 am:   Edit PostDelete PostView Post/Check IP

Graham, are semaphores what I call warning lights?
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Jonas TRACHSEL
Prolific User
Username: jonas_trachsel

Post Number: 129
Registered: 2-2005
Posted on Friday, 28 April, 2017 - 03:36 am:   Edit PostDelete PostView Post/Check IP

John
Semaphores are these swing-out illuminated arms for directional signalling. about 6" long.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1300
Registered: 9-2004
Posted on Friday, 28 April, 2017 - 05:48 am:   Edit PostDelete PostView Post/Check IP

Traficators is the other term!
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 1497
Registered: 4-2016
Posted on Friday, 28 April, 2017 - 07:33 am:   Edit PostDelete PostView Post/Check IP

Like these John,
https://www.youtube.com/watch?v=-n5ReqKpZdA

They have a habit of not working when they should like at Concours judging time LOL

Originally most did not flash, they just illuminated.
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John Beech
Grand Master
Username: jbeech

Post Number: 363
Registered: 10-2016
Posted on Saturday, 29 April, 2017 - 06:49 pm:   Edit PostDelete PostView Post/Check IP

One of my local television stations broadcasts an Australian television series called Dr. Blake Mysteries, which I especially enjoy for the car spotting. I've noticed some cars sport semaphores but have never observed them in action. Thanks for educating me about their function.

Meanwhile, back to the lamp your enthnical-taste wife procured. Would you kindly share photos of shadows and no shadows being cast, please? Perhaps even include a photo of the lamp itself. I am keenly interested in this effect you've noticed.

One thing to take into account is the incandescent bulb is a filament, which is held some distance off the surface and as it glows uniformly (e.g. 360), some portion of the light energy is being captured and focused by reflection off a parabolic reflective surface to cast light. In the case of headlamps, a lot of effort is put into placing the glowing element at the locus of the parabola. Or in the case of an interior-type light bulb, is covered by a frosted globe so as to softly illuminate evenly via diffusion (the point being to minimize shadows). Conversely, an LED is a point source light originating from a flat plane. By definition it cannot illuminate behind itself the way a glowing element does so the form the energy manipulation takes is also going to be different. For example, some are fitted with a miniature Fresnel-type lens (very short focal length) to permit being seen over a greater distance (think lighthouses). And in the automotive world, a new type actually aims the light backward at the existing reflective surface. Those fitted with lens are, in effect, almost functioning like a collimated light source (parallel beams of light). For a diffuse light effect, a strip of LEDs in a frosted tube of glass give the effect of a shadowless tube of light like a fluorescent light tube - speaking of which, I retrofitted my shop and warehouse with these and love them because, unlike genuine fluorescent tubes, these come on instantly even when it's cold, but I digress!

My point being, could this be the reason for the effect you've observed? Photos would help. Especially if you're willing to sacrifice the bulb integrity by removing the covering to show the arrangement of the LEDs themselves within the globe. I bet this leads us to case-and-effect.
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Patrick Francis
Frequent User
Username: jackpot

Post Number: 97
Registered: 11-2016
Posted on Sunday, 30 April, 2017 - 12:43 am:   Edit PostDelete PostView Post/Check IP

Hi John
I returned the LED bulb that I bought for that lamp, but I have used an LED bulb from another room and taken comparison photos. Interestingly, this LED bulb does have a slight shadow effect - more than the returned one - but you can still see the notable difference.

Both LED bulbs were frosted which, as you say, possibly contributes to the lack of shadows:







*
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1305
Registered: 9-2004
Posted on Sunday, 30 April, 2017 - 06:52 am:   Edit PostDelete PostView Post/Check IP

The caption for flashers!
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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 79
Registered: 2-2016
Posted on Wednesday, 03 May, 2017 - 06:19 pm:   Edit PostDelete PostView Post/Check IP

Regarding the ceiling lamp and 'casting interesting shadows", I suspect that that LED globe actually has multiple light sources, thus there are many shadows which all overlap so the lit area from one individual light source illuminates the shadow from the others.

The incandescent globe, with its single light source only casts one shadow, thus the much sharper pattern.
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John Beech
Grand Master
Username: jbeech

Post Number: 373
Registered: 10-2016
Posted on Wednesday, 03 May, 2017 - 08:44 pm:   Edit PostDelete PostView Post/Check IP

Jeff, I believe you hit the nail on the head. Multiple weaker sources casting multiple shadows. Explains it neatly. Well thought out and explained!

Patrick F, the shadows cast are fantastic. I congratulate you on your wife's superb eclectic taste!
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Patrick Francis
Prolific User
Username: jackpot

Post Number: 103
Registered: 11-2016
Posted on Wednesday, 03 May, 2017 - 10:48 pm:   Edit PostDelete PostView Post/Check IP

Thanks Jeff for your explanation and John for your kind comments.

How might this affect the look of our instruments, I wonder?
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Jeff Cheng
Frequent User
Username: makeshift

Post Number: 80
Registered: 2-2016
Posted on Sunday, 07 May, 2017 - 04:11 am:   Edit PostDelete PostView Post/Check IP

Understanding the difference between LED and incandescent globes.

An incandescent globe has a single point of origin light source in all directions with uniform brightness (by angle only, further away= dimmer, obviously).
An LED is directional by design. The primitive 'nipple' diodes focus light into a comparatively narrow beam, with the latest 'surface mount diodes' producing mostly uniform light, but only up to a hemisphere and the board that the diode is 'surface mounted' to means it can't light up behind itself. Modern developments pair these SMD's back-to-back, which give a close pattern to an incandescent globe.

Now that that's out of the way, lets look at what we want in an automotive setting:

For warning lights, you want something bright pointing straight at your eyes to get your attention. Cheaper directional LED's are fine for this application, and almost better, as most warning light housings don't have a reflector anyway to maximise a 360* output.

For gauge backlighting, you want a uniform lighting, so there are no hotspots where once part of the scale is brighter than the rest. This is where the incandescent globe is best, with it's 360* even output. Engineers design gauges around this, so that you never see the globe directly, and the globes are positioned so that the illuminated areas are equidistant from them, to give the effect of even lighting, despite the natural physics of "close=bright, far=dim".

Globe life is another consideration. A 3watt incandescent dash globe will last decades assuming your electrical system is up to scratch. The only LEDs certified/guaranteed for a similar life are almost 10x the cost of the same incandescent globe (Phillips/Osram). The cheap eBay globes WILL fail sooner. As an example, I run cheap eBay LED's for parking lamps in my daily driver. I my driving habits would be 'normal', but they usually fail after a year.
Whether the extra cost to NOT change your dash globes yearly by buying the $35 LED's is justified is up to you.

Similar brightness LED's consume much less power for the same output (or produce more light for similar power draw). A 5w incandescent can be replaced with a 1w LED. So assuming you replace the following with a 1w LED:
6 x external lamps (5w)
5 x dash globes (3w)
your wattage draw goes from 45w to 11w. Dividing the 34w difference by 12v gives an amps REDUCTION of 2.8A in current draw.
Those are the numbers, but only you can decide whether it's worthwhile. Keep in mind that a HVAC blower motor can draw 5-10amps, so running the fan unnecessarily easily outweighs any elecrical 'savings'. Again, your $0.50 5w filament globes will last decades.
Grand scheme of things and all.

One last point, LEDs come in many 'white' colors ranging from warm yellow all the way to cold blue, so you can change the backlighting to suit what you like. Some like the cold blue/white, I prefer a warm glow, especially in a classic car.

Personally; I replaced my interior overhead lights with brighter LED globes in the original 'warm' color to illuminate the cabin, same with my side marker lamps for safety. I won't touch my original dash globes until they fail, at which point I'll probably just replace them with incandescent replacements, since pulling dash panels yearly to save a few dollars is not my idea of fun.

That worked out WAY longer than I intended when I started typing... Sorry...
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 1519
Registered: 4-2016
Posted on Sunday, 07 May, 2017 - 08:47 am:   Edit PostDelete PostView Post/Check IP

Great post Jeff, and a very interesting read.

Your wrap up is exactly my thoughts and what I have said on another thread.
Lights, gauges and fittings designed for incandescent globes work and illuminate best with incandescent globes.
LED's don't throw the light as you clearly explained in the directions and angles required by the manufacturer of the said light.
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Patrick Francis
Prolific User
Username: jackpot

Post Number: 105
Registered: 11-2016
Posted on Monday, 08 May, 2017 - 07:14 am:   Edit PostDelete PostView Post/Check IP

Jeff
Comprehensive explanation, yet simple to understand.
Many thanks for you wise advice.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1327
Registered: 9-2004
Posted on Tuesday, 09 May, 2017 - 06:15 am:   Edit PostDelete PostView Post/Check IP

Some day time 12v led driveing lights that I made up useing the old bulb holder.
These were polarity sensitive.


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John Beech
Grand Master
Username: jbeech

Post Number: 378
Registered: 10-2016
Posted on Wednesday, 10 May, 2017 - 10:02 pm:   Edit PostDelete PostView Post/Check IP

Jeff, thanks for the well thought out reasoning vice LEDs versus incandescent bulbs, especially in the dash/instruments.

I'm leaning toward LEDs tail lamps largely for reasons having to do with safety. E.g. they illuminate more quickly and may be brighter. Investigation continues.
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Patrick Francis
Prolific User
Username: jackpot

Post Number: 110
Registered: 11-2016
Posted on Wednesday, 10 May, 2017 - 11:42 pm:   Edit PostDelete PostView Post/Check IP

Talking about lights, does anyone know if it is true that the Rolls indicators were designed to flash slightly slower than normal to give a more "regal" look. This was done by adjusting the bi- metallic strip in the flasher unit - apparently.
Also the very slight delay that an incandescent takes to illuminate(as John notes with LEDs above) adds to that effect.
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Michael Carr
Experienced User
Username: carsie

Post Number: 28
Registered: 7-2016
Posted on Thursday, 11 May, 2017 - 12:46 am:   Edit PostDelete PostView Post/Check IP

Patrick - liked your PostCard :-) - no-one else commented - Anyone dropped these?

Glasses

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