Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [lamp]

132 questions
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What are the little bits of metal that come out of light bulb filaments and why do they stick to only one terminal?

Recently I changed the headlights in my car and took a few micrographs of the filaments. A couple composite photos of old bulbs: For reference, here's a new bulb filament: On the left wire in the images of the old bulbs, there are many metal…
rsaxvc
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Does turning a lighbulb on and off repeatedly use more energy than just leaving it on for hours?

Let's say I have a 60W bulb in a lamp in my bedroom. If I kept the lamp on for 2 hours straight but the next day, I switched it on and off 10 times in intervals of 5 minutes. Which scenario would use more energy?
Christopher Chipps
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Will repeatedly turning a light bulb on and off damage it?

I have been hearing a common saying that if one keeps switching the lights on and off you will probably damage the light bulb itself, since every time you close the switch there would be a sudden rush of current through the circuit. Given that we…
Derek 朕會功夫
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Why does a neon lamp indicator on a power strip switch flicker in the dark?

Neon lamp indicators embedded in power strip switches indicate whether the switch is ON or OFF. When the neon lamp is ON in a dark environment (lights of the room are off), the lamp begins flickering and it sometimes goes off for a few seconds. When…
Hamid Rouhani
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What explains this bulb/motor behavior?

My son was building circuits with a hobby kit. He tried connecting a small DC motor and incandescent bulb in series with two batteries. The motor is not marked, probably is rated at no more than 6V. The lamp is marked 3V. The motor shaft spun,…
nuggethead
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Neon lamp symbol

I am new to neon lamps: I just discovered its electronic symbol: I am a little bit confused, What does the dot in the symbol mean? It looks like the neon lamp is polarized. How do I know what lead of the neon lamp corresponds to the dot? I have…
Dau
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Why did a spark occur between my HDMI cable and metal lamp base?

Edit: Update 1/2/22 @ 2:27 UTC: outlet tester shows that all outlets and power strip outlets being used were normal. Update 1/2/22 @ 21:07 UTC: performed various continuity tests which suggest to me that the monitor, HDMI cord, and PC are normal,…
dfncrbl
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What's the problem in designing a bright enough LED lamp?

So far the most powerful household LED lamp I've seen had consumption of 2.1 Watts and gave light equivalent to maybe 15-25 Watts incandescent lamp. That's maybe good for illuminating a Christmas tree, but totally unusable for using as usual…
sharptooth
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Lighting metal halide lamp

I want to use some metal halide lamps (5-7*150W) to get some decent lighting in my room. Unfortunately, inductors for these lamps have weight about 2kg each. I cannot accept 10kg of metal hanging near the ceiling :-) So I must go with electronic…
BarsMonster
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Why plug is polarized in the US? What are the benefits?

I could not get a good hold of it, I searched online quite a bit. This must have to do with safety but then non-polarized switches are used through out the world with no issues are risks, so my question why use polarized socket where one blade…
TheTechGuy
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Driving 12V halogen lamps (downlights)

12V halogen lamps, do they need any special driving? I have seen on some transformers that they output Half-wave rectification to the 12V halogen lamps. Is this how they should be driven or can they be used with DC or AC as well?
Max Kielland
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Uniformly illuminate an array of LEDs: how to get the most homogeneous output?

Please note: this question refers to the electrical engineering part of the design, optical configuration is not request (advices are however welcome) I'm trying to design a LEDs lamp with an homogeneous output for a radiometric experiment (so I…
G M
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I need to test multiple lights that turn on individually using a single switch. I don't understand the use of diodes in this diagram

I have the diagram below. Wire 4 has a phase of 120VAC and N is the neutral. I need to test several lights that turn on individually each one using different contactors that are activated by sensors (simply switches) using a single switch called…
Eduardo Vieira
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Can I use a single LED from a 220V LED light bulb to repair my 1.5V LED flashlight?

Update: I couldn't desolder any LEDs from the donor board without destroying them. They simply refuse to come off. This raises the question for me: Are they even soldered there or manufactured as they are together, and cannot be desoldered? My…
NerdyNerdie
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Calculating parallel resistance of a rated bulb

I have a bulb rated 110 V, 60 W and is in series with another bulb which is 110 V, 110 W. It's being powered with a 220 V source. Now, what would be the resistance of the resistor to be added in parallel to the first bulb so that each bulb will get…
vvavepacket
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