Loony Question for Today

Sno-o-o-ort! Old office fan with light fixture, one single 150W Halogen, 18 years old, fails. New weenie fixture made impotent by leftist rules takes 3 x 40W incandescent... strange, eh? I'm trying to get light output up. I may end up rolling my own LED... multiples on a round PCB to fit the "globe". ...Jim Thompson

Shove it, Larkin. I forgot nothing. (If you could read and comprehend, you'd know I was barbing John S, not you.) I just have no lab handy to measure thermals on incandescent versus Halogen. I thought Halogens might throw less heat... true, but not as much less as I hoped. I'll probably roll my own LED structure if I can't find something OTS to stuff in the globe from 1000bulbs.com ...Jim Thompson

What about the light, if it doesn't leave the room?

Ok, you're forgiven (this time only).

The eco-leftist commie liberal green rules are for your own good. It saves energy by requiring you to buy 3 times as many fixtures, 3 times as many lamps, and pay 3 times as much for them. You're going to save energy even if it costs you extra cash. Think of it as part of job creation.

By coincidence, I had a similar problem. I needed overhead illumination from a fixture known to trap heat and burn out CFL bulbs. CFL bulbs just didn't last running with the fluorescent tube heating the electronics. Taking a step backwards, I found myself illuminating the ceiling rather than the area below the lamp fixture. A screw type LED "bulb" repeated this mistake by also lighting the ceiling. I eventually found that three 45 degree LED flood lamps put most of the light in the desired area. With your arrangement, a similar arraignment might be suitable (unless you enjoy looking at an illuminated ceiling).

With 3 fixtures, you might look into "flood" type lighting. 45 degrees beam width is fairly common. 60 degrees can be found, but is more expensive:

However, that's too easy and rather boring. Since you have a ceiling fan, I think it would be cool to attach a row of LED's (LED tape) to each flan blade, for illumination. It won't be very bright, but it would be much more fun to build and watch:

Maybe some color?

I think these are LED's.

Maybe make it wind-powered ?:-)

...Jim Thompson

Only if you have a suitable source of rising hot air directly under the fan blades. However, without a ducted fan arrangement, it will be rather inefficient.

You might be thinking of an outdoor wind turbine. You could install it on a rooftop tower, run a speedometer cable to the indoor fan through the ceiling, and drive the indoor fan directly.

Powering the LED's on the fan blades is fairly easy. Attach iron core solenoid coils near the ends of the fan blades. Install a circular ring of magnets with alternating polarities around the circumference. Such a generator should provide sufficient capacity to run the LED's.

=A0 =A0...Jim Thompson

In winter I feel sorry for the neighbors who put chicken house turbines on their roofs, to exhaust hot air from the attic in summer. They don't cover them in winter, and you can see them merrily spin away, as their hard-earned heating money goes up and out into space.

I have my own loony idea. You all know how the Sonicare toothbrush charging circuit works, right? What if the primary of a similar transformer rotated with respect to the secondary, instead of being stationary? Then you could mount the primary coil assembly on the non moving light fixture part of the fan, with the secondary on the rotating fan assembly. Could there be enough coupling to drive some LEDs?

But everybody has heard about low-power halogn floor lamps falling over and starting fires, and their power is in the same common range of 40-100W. Those things do get hotter than incandescents, and not just because the heat is concentrated in a smaller bulb since the whole lamp head gets hot. This is just based on my sense of touch of course but they seem to run hotter.

Assuming you mean a ceiling fan with co-axial lumiere, try fittin the old lumiere to new fan, AIUI it's a standard thread.

More likely some designer decided that the three smaller globes would allow a more streamlined package, possibly this was a compromise after a T9 was ruled out on cost.

how about 60W T9? (ring shaped rluorescent tube) might fit in the existing package.

Assuming you mean a ceiling fan with co-axial lumiere, try fittin the old lumiere to new fan, AIUI it's a standard thread.

More likely some designer decided that the three smaller globes would allow a more streamlined package, possibly this was a compromise after a T9 was ruled out on cost.

how about 60W T9? (ring shaped fluorescent tube) might fit in the existing package.

There are two forms of heat involved here. Thermal radiation and warm air the relative proportions vary with the type of lamp.

You haven't defined what you mean by "heat" but taking it to be thermally damaging radiation capable of scorching lampshades.

The *peak* emission even of the quartz halogen lamp is still in the near infrared even for a halogen bulb run at 3300K so the flux of thermal IR from a quartz halogen is more likely to start fires. The small red hot envelope and tendency to explode adds to the excitement.

More short wave visible photons are emitted by the quartz halogen filament at a higher temperature but well over half of them are high temperature thermal IR (anything characteristic of 600K and above).

Has graphs of the BB radiation curves for 2500K through 3300K. This applet will let you plot some suitable curves as a function of temperature set Tmax=3300 (tungsten isn't quite a black body)

Mains quartz halogens come with a warning that they are unsuitable for desk lamps in part for this reason (they are double glass envelope).

Once it has thermalised in the room 40W total dissipation is 40W of heat ignoring any light that escapes out of the windows. You can feel the beam of heat radiation from a directional quartz halogen fitting.

More light and heat radiation is emitted from a quartz halogen lamp as a proportion of the electricity consumed and a higher percentage is at visible wavelengths but the peak emission is still around 900nm.

An ordinary filament lamp loses a larger proportion of its heat by convection of warm air from the physically larger but cooler glass envelope.

Well if you want to set fire to the lampshades and burn your house down go right ahead. I take it you flunked physics at MIT.

=A0 =A0 =A0 =A0...Jim Thompson

So he never learned any of it in the first place.

"Throw"? Where?

So why didn't he pose the question in terms of heat radiated, rather than using the portmanteau term "heat" which lumps together the radiative, conductive and convective routes?

In other words, radiated/convected heat is a problem - he still hasn't told us which or why.

This was the kind of half-baked unspecific question we get from dim newbies.

-- Bill Sloman, Nijmegen

and

eat

This

The whole point about halogen lamps is that they run hot enough - or a least the inner silica glass bulb does - that the tungsten vapour from the filament which deposits on the inside of the bulb is hot enough that the halogen gas inside the bulb with react with it to form tungsten halides which are volatile at the temperature of the inner bulb.

That's a lot hotter than the bulb of a regular incandescent lamp. The halogen lamps that I use put the silica inner bulb inside a regular soda glass outer bulb - so the hot inner bulb can't set anything on fire, and you can't put your sodium-rich finger-prints on the outside of the silica inner bulb to degrade to the silica.

-- Bill Sloman, Nijmegen

It eventually degrades to ambient heat, but it's spread fairly widely around the room so it doesn't usually matter.

Jim seems to be - correctly - worried about over-heating his light fitting. His original post didn't make that clear.

-- Bill Sloman, Nijmegen

Too close to call, what wattage, what type of halogen lamp, etc... The difference is so slight that it probably is not worth considering. (say a standard incandescent lamp is 2.5% efficient, and a quartz halogen is

Many are fooled by the smaller envelope size of a quartz halogen (which does get hotter) but once you move away from the lamp a fixed amount the heat values are probably equal.

Measurement would clearly show what's generated with a set of specific test lamps however. All needed is an insulated, fireproof box with a fixture and the ability to measure the box's internal temperature. Test each bulb for a fixed (equal) time period and measure the temperature rise in the box vs time.

=A0 =A0 =A0 ...Jim Thompson

=A0 =A0 =A0...Jim Thompson

a 40W lamp in a box that doesn't let light out will add exactly 40W to the box

the only thing you would be measuring is how well the box is insulated

-Lasse

The CAN be closed ff from inside the qttic & still spin.

That's a rotary transformer, like used in video tape machines. 60Hz would require a large core, but 100 KHz would be no problem if you can figore out a way to mount it that won't cause the minor vibration from grinding away the ferrite.

But do incandescents really create more heat, spread over a larger glass and conducting it to the air faster?

Jeez! At least in the North, you want to do the same in the Winter. The attic *should* remain cold so you don't get ice dams and mold. Attic ventilation is crucial year round.

Hey, I bet you could do a similar thing and power the fan, itself!