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Registered Member #1822
Joined: Fri Nov 21 2008, 08:04PM
Location:
Posts: 300
I have decided to make a light bulb. I dont particularly care how much power it uses although a practical limit would be ~150Watts or how much light it puts out although, it should be more like a light bulb than a glowing piece of wire.
So far my ideas are thus, wind a very tight coil of mid gauge nichrome wire and place it in a low pressure chamber full of CO2.
I think that I should definetly place several coils within so that I can find voltage limits and over voltage one of them to ensure that all the O2 has been burnt or displaced.
Registered Member #103
Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845
on the secret life of machines (series 3, electric light) they made a light bulb using a milk bottle, and a pencil lead as the filament! It looked a bit temporary, the vacuum pump had to run all the time I think. Not very efficient but it worked!
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
The melting temperature of nichrome wire is about 1400 deg C, that means that you will get little visible light and very little blue light. So the efficiency will be awful and the colour balance terrible.
Tungsten has the highest melting point and is the most suitable material, for experiments graphite from a pencil is quite usable. If moisture is trapped in the graphite it might explode quite violently so watch out for your eyes.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
Planning how to get the current into the lamp would be a good starting point. With access to chem lab glass tubing, simple glassblowing would be a good project outcome. Thomas Edison, Chemist [American Chemical Society] 1971. is interesting.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
cduma wrote ... So far my ideas are thus, wind a very tight coil of mid gauge nichrome wire and place it in a low pressure chamber full of CO2. I think that I should definetly place several coils within so that I can find voltage limits and over voltage one of them to ensure that all the O2 has been burnt or displaced.
One reason nichrome is popular as a heating element for kilns, etc. is that it can be heated almost to its melting point, in ordinary air, and still have a usefully long lifetime. Think of it as a kind of stainless steel.
By pumping out the air you will increase the thermal resistance, so less power will be needed to reach a given incandescent temperature. I don't see how CO2 would be a significant improvement over air.
Registered Member #902
Joined: Sun Jul 15 2007, 08:17PM
Location: Pacific Northwest USA
Posts: 1042
try a different metal, maybe a bit of tungsten wire if you can get it, carbon electrodes, or possibly a carbonized fabric like edison originally used
but the main concern is making an inert atmosphere for whatever you use so that it doesn't just burn out instantly, use something like Argon which will displace air on it's own pretty easily.
popular science also had an article about doing this a couple of years ago. here
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
Not really my area but since by removing the bulb from the lamp of a domestic lightbulb, you would have a good start at practicing the vacuum/glass welding etc. ?
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Making an Incandescent Light Bulb
