Questions tagged [light]

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

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How do seven segment displays show black numbers?

Usually, seven-segment displays emit red coloured light, which is understandable. But in digital watches, the common colour used for the numbers displayed is black. But black light itself can't be ...
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1 vote
1 answer
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IR LED Safety: Subtend Angle and Retinal Exposure Limit

The relevant formulas from OSRAM AN090 "Eye safety of IREDs used in lamp applications" with slight modifications : $$ Z = (l + w)/2 $$ $$ \alpha = Z/d $$ $$ L_{ir} \approx \frac{I_e R(\...
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35 views

How to change the wavelength of LEDs in Proteus?

I have a problem in designing a circuit for my project. Can anyone explain how to simulate an LED with 940, 1550, and 1650 nm in Proteus software? Dors the emission coefficient of LEDs in Proteus help ...
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1 vote
1 answer
78 views

How to calculate the total power of a LED using solid angle?

I have a LED with the max power of 130mW/sr and an opening angle of +-10° (so approx. around 20°). I conducted an experiment using this LED, the LED shines light to an un-doped silicon semiconductor ...
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1 vote
3 answers
113 views

Why are metal halide bulbs always ~130V?

I noticed that - even though the local voltage is 240V - metal halide bulbs are always sold as 130V bulbs, and their product sheets list the maximum voltage as 130V. Do perhaps all flood lights that ...
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1 vote
0 answers
45 views

Incandescent light bulb in proteus

How to create a simulation model of The incandescent light bulb in Proteus?
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1 vote
1 answer
111 views

What is this through-hole component holder used on aluminum PCBs?

I've been buying these cheaps LED lightbulbs and tore them down to see how the LEDs are driven. On all of them I have found this surface mount component that allows a through hole component (here a ...
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0 answers
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Creating ZigBee RGB Compatible Light - Raspberry Pi

I currently have a Rasberry Pi hooked up to a 64x32 LED matrix. It runs some custom Python scripts to control the colour and display of the matrix, which works great and lets me adjust the settings ...
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3 votes
5 answers
671 views

What is the mathematical relationship between the resistance of an LDR and light intensity in lux?

I have been surfing the internet and my physics books for the relationship between the resistance of an LDR and light intensity (a formula), and so far I have found nothing. If any of you have a ...
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4 votes
7 answers
869 views

Is it possible to control the frequency of light?

I mean, controlling directly in the source, not filtering the light or arranging density of the medium. For example, brightness can be controlled by current or voltage directly. However, when I came ...
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0 votes
1 answer
43 views

Photo Diode Receiver

I have designed a 5KHz Photo Diode Receiver circuit that Consists of a number of blocks. first stage of this circuit is a TIA. I have problem with DC IR Light (Like SUN Light), when sun light shine on ...
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2 votes
3 answers
991 views

Why did this fog lamp turn on with either configuration of power/ground? [closed]

My friend and I were replacing a burnt out fog lamp on his car. When it was time to make the connection, I wanted to make sure which wire was power and ground, so we don’t cause a short to the new ...
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1 vote
1 answer
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Antiparallel LED Fairy Lights Hack

I have this string of USB powered LED fairy lights that came with an IR remote. I had initially planned to plug these into a smart outlet, using a phone charger adapter, in a place that isn't easily ...
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-7 votes
1 answer
90 views

I have to build an LED lamp with a lithium battery [closed]

I don't understand much about electronics, I just know that the battery is very dangerous. These are the links of the components that I will use: BATTERY 3.7V 4400mAh LED 11,9V 1050mA STEP UP BOOST ...
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0 votes
1 answer
56 views

light LED panel symbole meaning

Please if anyone know what does mean this symbole.
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0 votes
8 answers
247 views

Using 110 Vac incandescent light bulb at 220 Vac with a series diode

I have a 110 Vac incandescent light bulb but I need to use it in 220 Vac. If I add a diode in series with the bulb, the RMS power is the same as before but the peak value of voltage and current is ...
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0 votes
3 answers
119 views

NAAAILTAC: Not another "add an indicator light to a circuit' question

There's quite a few places online where you can find out "how to add an indicator light into an existing circuit," but I can't find any that tell WHY the light needs to be added in a certain ...
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2 votes
3 answers
409 views

Help identify IC

This is an LED light from AI, PRIME 16HD model. I have identified the IC that seems to be burned; it looks like it's some kind of voltage regulator. I think the markings are: BN0D 18. Maybe someone ...
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0 votes
4 answers
107 views

How can a lidar achieve cm-level resolution?

In order to achieve cm-level resolution, it seems like a lidar would need to have extremely high sampling rates. Here's my thinking: Light travels at roughly 3·108 m/s, or 3·1010 cm/s. We need to ...
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4 votes
2 answers
768 views

How do the non-circuit old Christmas lights flash?

I have a 80's Christmas incandescent light string without any kind of electronics. They are static until you replace one normal bulb with one marked bulb. It seems to be that the marked bulb (that ...
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0 votes
0 answers
32 views

Transparent displays that allow UV light/sunlight to pass through them?

Is there a type of digital display that can work to let sun through it, so that the dark pixels block the UV, and transparent pixels let the UV through? I'm aware of monochrome LCDs for a resin ...
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1 vote
0 answers
51 views

What is the possible reason that cause the failure (burnt) of PTC in an electronic ballast?

What is the possible reason that might cause the failure (burnt) of PTC in an electronic ballast? I have been using this VOSSLOH SCHWABE brand electronic ballast and recently it has been burning up ...
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1 vote
1 answer
105 views

Can I make an LED turn OFF when current ON, and ON when current OFF?

Im an electronics noob so this may be a stupid question....but here's some context to my problem. I am rebuilding a motorcycle and have swapped out the dash. There is a wire coming off the bike to ...
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0 votes
1 answer
88 views

Finding the PPF and PPFD using a LED data sheet

I would like to design my own grow lights to grow indoor plants like strawberries, herbs, etc. But I have a problem that I need some help to work out: How many LEDs do I need to light up an area of 0....
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2 votes
0 answers
99 views

Help to understand the circuit function for me to repair - 30W LED ceiling light

I have a 30W LED ceiling light that has an adjustable LED temperature and is dimmable. It has a center lower power night light. It is controlled via an IR remote. I need advice on how to repair the ...
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0 answers
110 views

Stray voltage on light fixture

I have installed a led panel on a previously existing light pole in my house. It has the feature of switching light colors if you flip the switch quickly. If the switch is left off for some time and ...
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-3 votes
2 answers
72 views

What LED color temperature should I choose? [closed]

I am planning to start a new company, but I don't have much funds. I am thinking about what led light should I choose as the light in the office area. Can it achieve the two conditions of being cheap ...
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0 votes
1 answer
69 views

Need help on solar light auto on off dawn to dusk

I have 36 Ah battery. I will charge it through solar change controller or through inverter. I want to connect this battery to two 9 watt DC LED garden lights which will turn on and off automatically ...
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0 votes
1 answer
56 views

My "Sun up" circuit is malfunctioning in circuit, but works fine on USB test bench

I am trying to build a circuit to use the Arduino Uno R3 as a switch for a relay which makes a connection only during daylight. I don't know much about my LDR, pretty sure it is a 10K. I am dividing ...
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0 votes
2 answers
241 views

Glass of microwave oven

From a user who "doesn't know" anything about Maxwell's equations. How to explain simply the behavior of a transparent glass of a microwave oven? Lets the light pass ... but blocks the "...
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0 votes
2 answers
57 views

Trying to measure solution's color intensity. Is there any way to stop voltage variations?

I am trying to build a spectrometer to measure the color intensity of a solution. By chemistry I can make up a solution that has exactly 1 mg of gold in it and another that has 5 mg of gold in it. If ...
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0 votes
2 answers
102 views

Adjustable Sensitivity in a Light Sensor Circuit

I've designed the following circuit for detecting light and darkness and it seems to be working fine. I want to be able to set both LEDs to be off at a particular light sensitivity and to only come on ...
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0 votes
1 answer
76 views

I Need Help Making a Weird Custom Flashlight

As said in the title, I am trying to make a homemade flashlight. I have no experience when it comes to electrical engineering and I have a very basic understanding of this stuff. What I am trying to ...
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0 votes
0 answers
53 views

Parallel light failed to work, one light get's blow other remains good. How to get it working?

I'm using a mobile battery (4V) to power the two (each takes 3.0V) light in parallel since series circuit won't work with one battery. After connecting the wire, for a short time it did work. Then one ...
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0 votes
2 answers
80 views

How good are Time-Of-Fligt (light) sensors for measuring small objects?

I found this sensor VCNL4040 and it has the emitter angle and the sensor angle. Question: How good is a Time-Of-Flight (light) sensor to measure small objects that are 100mm away and about 20x20mm in ...
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0 votes
1 answer
42 views

How wide is IR-led light from VCNL4040?

I have an issue to solve. I'm going to measure an object that looks like this. My question is if the sensor VCNL4040 have a very wide spread light or very "laser-like" light that ...
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0 votes
1 answer
38 views

Changing a homemade LED light (14V Battery Pack) to run off mains?

I've got a wee challenge on my hands. My ex-girlfriend gave me this light as a b-day present 3D printed. I've been told that the LED is a 10mm Ultrabrite LED. See the picture attached for the battery ...
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0 votes
2 answers
49 views

Need help with configuration of a touch sensing lamp project! [closed]

I am currently a design student in university, and am attempting to configure a large scale project for my final. The idea is that there would be a lamp, with one person holding onto either (wire? ...
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0 votes
1 answer
121 views

What is a single-flash transistor-and-capacitor circuit actually called?

The internet is awash with diagrams where two lights alternately flash with the aid of transistors and capacitors. However, I remember at school being shown an introductory circuit in which one light ...
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0 votes
1 answer
137 views

Backfeeding MCU gate output bad?

I am trying to modify a work light (1S3P 18650 3,6V) that is controlled by an 8 pin PADUK type micro. An output from the micro goes through a 100 Ohm resistor straight to the MOSFET gate. It has the ...
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2 votes
1 answer
86 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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26 votes
7 answers
5k 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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-1 votes
5 answers
123 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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0 votes
1 answer
63 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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-1 votes
1 answer
45 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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0 votes
2 answers
74 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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0 votes
1 answer
96 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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0 votes
1 answer
130 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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0 votes
2 answers
239 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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2 votes
1 answer
472 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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