Dimming 500W incandescent bulbs for art project

coffeedragon

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I picked up a case of assorted 500w incandescent bulbs at a local thrift shop for a few bucks with the intent to turn some of them into an interesting/artistic lighting fixture. The bulbs are a bunch of different shapes, some with reflectors and some just giant clear globes. The problem is they're all 500W and if I hook them to 120VAC they damn near blind me.

Before trying anything crazy, I figured I'd check in here to see what folks think about instead hooking them to something like a 12vdc supply. I've got a lot of them laying around from other projects, ranging from 500mA to 5A. I'd rather power them straight from a supply than using a dimmer since it will be more efficient and give off a lot less heat. I just don't know what would happen if I hooked up one of these monsters to a 12vdc supply since they're 500w 120vac.

Any ideas to light them up at significantly less than their full power would be greatly appreciated.
 

CoveAxe

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Yes, you can run it from 12V, but they will be extremely dim and inefficient. You are much better off running it off of a dimmer which is actually designed to work with these.
 

Megatrowned

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Most standard household dimmers are rated for 600 watts, so one bulb per dimmer. However, you can find 1000 watt dimmers as well.
 

FRITZHID

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If you hook those up to the smaller power supplies, they will work but for a limited time. The supplies will eventually cook.
Connecting them in series will dim them significantly.
They used to use variacs (autotransformers) in some cases, combined with several different standard transformers you could get a wide variety.
 

SemiMan

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I picked up a case of assorted 500w incandescent bulbs at a local thrift shop for a few bucks with the intent to turn some of them into an interesting/artistic lighting fixture. The bulbs are a bunch of different shapes, some with reflectors and some just giant clear globes. The problem is they're all 500W and if I hook them to 120VAC they damn near blind me.

Before trying anything crazy, I figured I'd check in here to see what folks think about instead hooking them to something like a 12vdc supply. I've got a lot of them laying around from other projects, ranging from 500mA to 5A. I'd rather power them straight from a supply than using a dimmer since it will be more efficient and give off a lot less heat. I just don't know what would happen if I hooked up one of these monsters to a 12vdc supply since they're 500w 120vac.

Any ideas to light them up at significantly less than their full power would be greatly appreciated.


12V into a 120VAC incandescent bulb is called a heater. There would be no light. Light output is proportional to about V^3.4, power about V^1.6

So at 12VAC, no light, just a 12.5W heater. This is highly approximate due to the large voltage change, but close enough for concept. Power is not = V^2 because the resistance drops as it heats up.

Semiman
 

Anders Hoveland

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If you wire two of the bulbs in series, they will each consume 125 watts. The light will be very dull and orange-tinted.

(because the filament will only be a dull orange-white hot, the amount of light will be much less (maybe by about half) than a regular 125 watt light bulb)
 

SemiMan

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If you wire two of the bulbs in series, they will each consume 125 watts. The light will be very dull and orange-tinted.

(because the filament will only be a dull orange-white hot, the amount of light will be much less (maybe by about half) than a regular 125 watt light bulb)

The amount of light per bulb will be about 9% of what it at 120VAC. That is per bulb, so 18%. Visually, it would appear to be higher. Total power will be about 65% of one bulb, or 325 watts.
 
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