Lamp anomaly

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I tested a 75W Osram clear lamp & a 70W No Frills  halogen (claims
100W equivalent)  -  the Osram measured 54ohms and the halogen 56ohms.

On 240V, the Osram drew 325mA and the halogen 302mA.

The resistance rises are 13.7 times and 14.2 times  =  essentially the same
filament temps.

However, the filament in the Osram is longer by about 40% plus the wire is
also slightly thicker.

Now, light output is proportional to surface area for equal temps, so the  
MUST  deliver more light.

Putting each lamp inside a white, 15cm spherical ceiling fitting and using a
DSE lux meter  -  I found the Osram put out fairly even light in all  
while the halogen is uneven and quite poor in the downward direction.

Dunno which is brighter overall - SFA in it really.

Except one is banned and the other is legal ......

...   Phil

Re: Lamp anomaly
On 02/10/13 14:06, Phil Allison wrote:
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Pretty interesting, Phil. Is it possible that different filament composition
could mean that the filaments are not actually at similar temps though?

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They're double coils aren't they (a coiled coil)? Can you actually see this?
My eyes aren't good enough to pick it, but with enough magnification it's

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Is all the emission from the metal surface, or does some come from a partial
plasma around the surface? Because the extent of that plasma would change
the effective surface area.

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Hmm, right where you're most likely to want light. That's pretty crap.

Clifford Heath.

Re: Lamp anomaly

"Clifford Heath"
 Phil Allison wrote:

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** The colour of the two lamps looks very close, the halogen is a tad  

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**  Nope -  simple coils that look identical.

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** The gas ( ie nitrogen or iodine) would be convecting rapidly near the  
filament and AFAIK does not ionise.

   A longer coil at the same temp must deliver more light.

....   Phil

Re: Lamp anomaly
On 2/10/2013 2:06 PM, Phil Allison wrote:
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**Another good reason why I always avoid dodgy lamps and stick to decent  
manufacturers. The worst I've seen are those Mirabella crap.

On a related matter, I recently purchased an Ecogem S9041 WW (Warm  
White) 11 Watt LED downlight. Not only does it deliver respectable light  
output (680 Lumen), but the spread of light is similarly impressive (it  
is fitted with a nice diffuser). It is supplied with an electronic  
'transformer' that is suitable for use with dimmers.

Anyway, a friend is fitting her new home with LED downlights and I  
suggested she examine the Ecogem. Naturally, she reacted with horror at  
the price $46.00 wholesale) and elected to use some $20.00 ones she  
found. Sadly, she finds that she needs more than twice as many to do the  
same job as the Ecogems. More holes, more electricians' time.........  
Reliability is unknown.

A fool and her money............

Trevor Wilson

Re: Lamp anomaly
On 11-February-2013 10:16 AM, Trevor Wilson wrote:
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I've had those incandescents literally explode off the ceiling and  
shatter on the floor!

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Re: Lamp anomaly


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** Errr -  like this:

 See half way down the page.


The other two CFLs were ready to go the exact same way.

Woolworths  " ESSENTIALS "   brand  20 watt and 22 watt.

....   Phil  

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