Questions tagged [light]

Light is a tag about anything generates photons in the visible spectrum

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1answer
16 views

LCD prints black text on blue screen, but can print white on blue when bugged out

I am using the esp8266 which can supply 3.3V to power on an LCD 16x2. However, I am running into trouble regarding the visibility of the LCD's contents. The LCD prints black text on a blue background ...
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7answers
4k views

Is it possible to generate light with an antenna?

An antenna (e.g. a dipole) is able to radiate at a certain frequency thanks to the EM field generated by a current provided by a signal generator at such a frequency. So, for instance: Voltage source ...
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5answers
108 views

Alternating current frequency

An introductory discussion of alternating current in a primer I was taking left me thinking. We don't see a light bulb flicker because the alternating happens at 50-60 Hz. If it takes 1.28 seconds for ...
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0answers
14 views

Trailer Light Conversion Module Not Working

I have a module with the attached schematic that I'm testing. On the left is the "vehicle" and the right is the "trailer" I don't have a load on the left side just inputting ...
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1answer
18 views

VCSEL to project a 2D array of dots [closed]

Background Apple iPhone Face ID uses VCSEL inside its dot projector to project infrared dots into a person face. Then an infrared camera captures the pattern to be used in a structured light algorithm ...
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1answer
41 views

Transmitter & receiver circuit for high voltage lights

I want to control my room's lights by wireless circuit - like RF or whatever. In my country, the lamps and lights work on 220V AC. I'm still beginner, I have done this before and it worked, but by ...
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2answers
67 views

Red laser that has a higher power output at 400nm than 623nm?

I am doing experiments using a red (623nm) LED. However, when I measured the power output I noticed that it is higher at smaller wavelenghts. I did the measurements using two different power-meters ...
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1answer
56 views

Cleanest way to solar-power a string of outdoor bistro lights

I'm trying to hang some bistro lights on my balcony — specifically, the SVARTRÅ outdoor bistro lights from IKEA. There's just one issue: the balcony has no power outlets, and I'm not going to snake a ...
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1answer
34 views

Lightest possible USB solar charger with 5V 2A to 3A output?

I'm doing a lot of wilderness expeditions an needs the lightest gear possible. I want to make a solar charger (for my nitecore nb10000) that is as light as possible and has a USB output 5V and between ...
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2answers
46 views

Examples of using a circular polarizer filter for LED display

I was looking for ways to increase the contrast of a LED-based seven-segment display like this against indoor ambient light, and found this comment on EEVblog suggesting using circular polarizing ...
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0answers
19 views

Can 85V 35W ballast support a 85V 50W bulb

I am having PHILIPS MPXL DL50/740 85V 50W PX32D but not having a suitable ballast to test it. I am not able to find suitable ballast but ran into a 85V 35W ballast will it support? Is there any other ...
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1answer
131 views

Accuracy of manufactured photocells (LDR) with respect to light intensity

I was looking through photocell (photoresistors) datasheets, like for instance the NORPS-12, especially the graphic on resistance value versus light intensity. In no datasheet could I find information ...
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4answers
119 views

What is waving in light? [closed]

I've been building an AM transmitter and it's generated a lot of questions. At the top is the electromagnetic wave. It may seem simple but I've yet to find an answer. As far as I know, light is made ...
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5answers
134 views

Alternating green and red LEDs circuit

I tried to design this without much success so any help would be appreciated. A circuit where initially in a 3-pin Bi-Color LED (Common Cathode), the red led illuminates. Then it switches off and the ...
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0answers
70 views

IR beam break sensor

I want to make an "IR beam break sensor" as per attached schematic. I would also like to add some sort of “time delay” to the schematic. When the beam breaks and the relay gets activated, I ...
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2answers
94 views

How can there be voltage across resistors in series when circuit is open?

If you have a circuit containing 5 resistors, and one of them gets damaged such that current can't flow through it, I assumed no current would flow anywhere throughout the circuit, and that the ...
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1answer
2k views

Why is my 50-600V voltage tester able to detect 3V? [closed]

I used non-contact voltage tester to test burned out Christmas lights. It says it can only detect in the range of 50-600V. One of the strings has 40 bulbs in series and none of the lights are burned ...
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0answers
34 views

Coin cell UV pendant Q2 [duplicate]

I am a beginner with LED lights, but would like to use a 5mm 365nm UV LED diode to make a pendant with a small fluorescent crystal. I would like to create a very simple, very compact circuit with a ...
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4answers
48 views

Controlling a single lightbulb from multiple switches

It is quite common to have a single lightbulb in the home that has two switches to control it. It works so that whichever way the light is (on/off) you can change the state of either switch and it ...
2
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1answer
105 views

Coin cell to power a 5mm UV LED?

I am a beginner with LED lights, but would like to use a 5mm UV LED to make a pendant with a small fluorescent crystal. (This is what I purchased (https://www.amazon.com/uxcell-365-370nm-Ultraviolet-...
1
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1answer
71 views

What is the name of this item contact pin?

I am making a box with lights inside of it. These lights are UVC lights, which will sanitize any items put inside. I have attached a photo; I would like to know the name of this item. I know it is ...
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1answer
58 views

Difference between \$\epsilon\$ and \$\epsilon_0\$?

I have been given the following equation for the speed of light: \$V = \Large {1 \over {\sqrt {\mathstrut \epsilon \cdot \mu}}} = {1 \over \sqrt{\mathstrut \epsilon_0 \cdot \epsilon_r \cdot \mu_0 \...
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2answers
105 views

Would connecting multiple light socket splitters together decrease lumens

Sorry if this is a noob question. I'm trying to build a very bright light by combining multiple light bulbs together with socket splitters. My thinking is simply to take three 7 in 1 light socket ...
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2answers
213 views

How can electrons in a tungsten filament release infrared light photons?

I have a question regarding electric circuits, specifically when it comes to converting electromagnetic energy into light in a light bulb (tungsten)filament. How can an electron in a tungsten atom of ...
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0answers
43 views

Interfacing Arduino with TSL235 (light to frequency converter)

I am working on an Arduino based circuit that uses light to frequency converter (TSL235) to trigger a buzzer when there is an intensity change in the ambient light (for example when a car is pointing ...
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0answers
15 views

How to measure intensity (lumen) of a light source?

Let's say I have an x800 cree LED (which was supposed to be 4000lumen) and a cheap lux-meter (thinking of buying one like this). My question is, which is the physical setup to measure the true ...
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1answer
95 views

10cm tube light source (see photo) - what is it?

I'm just trying to work out what this is: Neither the tube nor the blue box has any markings whatsoever that I can see. The tube is about 10cm long and appears to be transparent plastic with white ...
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4answers
129 views

Light sensor detecting when the lights turns on AND when the light turns off

I would like to create a circuit using photodiode that detects when the lights turn on AND when the lights turn off. The output should look something like that: I want to create the simplest possible ...
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0answers
25 views

Finding a XT60 connector switch with indicator lights

I'm looking for an XT60 connector switch (e.g. https://www.amazon.com/gp/product/B07K33LRW2/r), but need one with an indicator light so I can visually verify whether a current is flowing through the ...
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2answers
122 views

I’m an electrical idiot - can you help me?

I have overhead doors at the back of my office building. I wanted to wire up a large red LED next to the light switch so that when employees leave, the light would be red indicating the doors are up. ...
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0answers
55 views

temperamental LED light

I have installed LED tubes in my kitchen ceiling light. They replaced the old fluorescent tubes. I removed the ballast and wired the fixtures according to instructions which essentially connected the ...
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2answers
54 views

Determining current through LED light

Not an electrical expert so please bear with me. I bought a no-name brand LED lamp that I would like to use with my 9V DC adapter as power source. The lamp uses 3 AA batteries in series. Batteries ...
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2answers
65 views

Which booster for a battery powered LED? [closed]

I have a 9,6V 2000mAh Ni-Mh battery (with charger) and I was wondering how to use it to build a portable spotlight (= flashlight for video.) I need 30 to 60 minutes of battery so if I remember my ...
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2answers
95 views

LED indicators intensity standards

I am trying to find any resources on the LED parameters (i.e. preferred intensity and luminosity ranges) that are used as indicators in various home appliances, such as Networked devices (i.e. routers)...
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1answer
72 views

Turning old floor fan into floor floor study light

I have turned a cheap floor fan into a floor study lamp; i.e. 30cm of 240V 5W a/c LED (under cupboard) strip light facing down on to the desk. These LED strip lights can be easily daisy chained in ...
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0answers
62 views

Trying to seal light from LEDs on PCB

I have a PCB I'm currently working on in Altium where the only thing on the bottom are some LEDs that I'd like to mount through a cutout on a sheet of plastic, with all of the other components on the ...
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2answers
97 views

Theoretical question: Could an incandescent light bulb be used as a temperature sensor?

Let's assume a plain old incandescent light bulb. It runs on a fixed (assuming an ideal supply grid) voltage and will regulate the current going through it as its resistance raises with the ...
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0answers
40 views

How to power a 17W T5 Germicidal UVC Lamp?

I recently bought a SBL 350T Germicidal Lamp from American Ultraviolet, but have been having some trouble finding out how to power the lamp since I do not have much experience in lighting and the base ...
2
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2answers
133 views

Burn hazard of IR LED Array Question

I am performing eye safety calculations on a device and I have hit a roadblock. To perform the calculations I have been following the IEC 62471 "Photobiological safety of lamps and lamp systems&...
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0answers
45 views

Should the LED be on the lens side of a light pipe, or the other way?

The image below is from a Bivar cutsheet. I'm trying to figure out which end the led should be on.
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0answers
127 views

What is this IC “30=N26” in Philips hue garden light

I'm hoping to identify the IC in this Philips Hue garden light controller, in order to replace it. Suggestions on how to identify what it is, would be greatly appreciated.
2
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1answer
172 views

Why does this part of an OLED filter light only when orientated correctly?

Note: The screen is an OLED screen. I had assumed it was LCD, therefore the post mentions it as such. I was disassembling a Samsung phone (GT-I9305) and was able to seperate the LCD into two sections....
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0answers
49 views

Do I need the old earth connector when replacing GU5.3 bulb fitting with GU10

I'm switching out a GU5.3 bulb fitting including the transformer with the newer GU10 fitting that no longer needs the transformer. On the old GU5.3 fitting there was a metal connector attached to a ...
0
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1answer
94 views

12V lighted rocker switch getting hot even without load

Is it normal that 12v lighted rocker switches get hot even when the load is not connected? Attached is the schematic and the PCB layout for such switch: https://lcsc.com/product-detail/Rocker-...
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1answer
76 views

How an animation is done with LEDs?

while(true) {   movePlayer('upright', '10 * Time.deltaTime'); } Here, an animation is done. No button or mouse click is done. Everything moves automatically. How ...
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2answers
358 views

Can light damage a monitor/screen

I was reading some posts about how light can damage a camera by heating it up its internal components? Link: Can camera sensors be damaged by light? If I shine a 150-lumen flashlight at a monitor or ...
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2answers
596 views

How do I drive a 5W low-pressure mercury UVC bulb?

How do I determine the voltage and necessary power supply for this bulb? This bulb is a UVC low-pressure mercury vapor bulb used in my air purifier. It fits in a G23 Socket; normally I would expect a ...
0
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2answers
50 views

How turn off lights automatically?

I am trying to make system where I want lights to turn off automatically. It should work like that if someone kept lights on by mistake then it should turn off automatically without any human ...
3
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6answers
3k views

How do I calculate resistance when I have the voltage drop?

This is my circuit: 3 volts in with a 1k ohm resistor in series with the LDR. I have the voltage drop across the LDR but I need to find the resistance.
0
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1answer
48 views

Problem with new bicycle front led light and old bulb back light

I had a problem with my front bulb light at my bicycle. So, I bought a new one (LED) for the front, but somehow, the back bulb does not work anymore. I have checked the wires for loose connection, so ...

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