Even cooler microscope bulbs than LED?
http://www.telegraph.co.uk/news/science ... -LEDs.html
Return of the incandescent bulb?
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apochronaut
- Posts: 6327
- Joined: Fri May 15, 2015 12:15 am
Re: Return of the incandescent bulb?
GE has been working on something along these lines as well. I actually heard this from a light bulb jobber about 10 years ago, before leds became popular and compact fluorescents were beginning to show their true colours, which is groan. I have to say, I hate compact fluorescent and while I tolerate leds, I have always found them not a great deal more attractive. I tolerate them because of the supposed benefits but when it comes to microscope lamps, especially for the difficult applications, leds basically aren't really there and I am really glad that we may be getting back to lighting that doesn't compromise.
This is a good time to post this, because it was in the back of my mind anyway.
Bulb care.
Many of us still use tungsten lamps and probably many more use halogen. There is a life curve related to voltage for each of these. With tungsten generally, the service life goes dramatically up with reducing voltage, whereas with halogen it does for a while , then starts to go the other way.
A 5% reduction in voltage , increases tungsten bulb life by about almost 100%, whereas a 5% increase shortens the life by about 45%.
A 10% reduction in voltage , increases tungsten bulb life by about 300%. A 10% increase and , where did I put that spare bulb?
Halogens also burn off tungsten vapour but the halides, capture it and recycle it back to the filament. The life expectancy of a halogen bulb, relies on an adequate temperature to effect this recycling of the tungsten. So, yes, reducing the voltage by 10 % increases the filament life dramatically but at a certain point( probably about a 15-20% drop in voltage), the temp. drops , the colour temp. gets off too much and the temp. threshold to efficiently create the recycling loop isn't met. The bulb carbons up the quartz envelope,with burnt tungsten, reducing illumination and evaporates the tungsten filament prematurely.
This is a good time to post this, because it was in the back of my mind anyway.
Bulb care.
Many of us still use tungsten lamps and probably many more use halogen. There is a life curve related to voltage for each of these. With tungsten generally, the service life goes dramatically up with reducing voltage, whereas with halogen it does for a while , then starts to go the other way.
A 5% reduction in voltage , increases tungsten bulb life by about almost 100%, whereas a 5% increase shortens the life by about 45%.
A 10% reduction in voltage , increases tungsten bulb life by about 300%. A 10% increase and , where did I put that spare bulb?
Halogens also burn off tungsten vapour but the halides, capture it and recycle it back to the filament. The life expectancy of a halogen bulb, relies on an adequate temperature to effect this recycling of the tungsten. So, yes, reducing the voltage by 10 % increases the filament life dramatically but at a certain point( probably about a 15-20% drop in voltage), the temp. drops , the colour temp. gets off too much and the temp. threshold to efficiently create the recycling loop isn't met. The bulb carbons up the quartz envelope,with burnt tungsten, reducing illumination and evaporates the tungsten filament prematurely.