Questions tagged [light]
Light is a tag about anything generates photons in the visible spectrum
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Calculating the wattage of a speaker protection light bulb
I have a very old musician's singing system in my hobby room. Yesterday one of the speakers broke down. In search of the cause, I finally opened the speaker box and found two light bulbs inside. One ...
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What quantity remains fixed when the voltage changes? [closed]
Suppose I have an electric lamp that is designed to be connected to a 220 volt network.
Then I take it to a country with a 110 volt network, and connect it using an appropriate voltage converter. I ...
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Is it safe to charge a 4v lead battery with 5v charger and a diode?
I have bought this Chinese SMD charger light that comes with 5v usb charging port.
I have just opened it to see how it charges with a 5v charger. After opening it I have been very surprised to see ...
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Radioshack LEDs triggered by computer HDD light: how do I trigger these multi colored LEDs to change color. Grounding 3rd lead triggers them
I have purchased Radioshack LEDs, catalog 276-0016. These are a 3-lead LED package with GND, VDD and a MODE pin. Each grounding the MODE pin changes the color or operation mode of the LED. I want to ...
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A circuit to dim an LED whenever it gets dark
I want to make a circuit to automatically control the brightness of an LED.
I want the LED to be at its brightest when it is brightest outside, and to start dimming as it becomes dark outside.
I was ...
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Interference from ceiling fan light with my wire FM radio antenna
When I turn on my ceiling fan LED light it interferes with my FM radio wire antenna, so I used normal copper wire soldered to the wire antenna and extended to my window about 1meter long. It was ...
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Why does my LED bulb light up dimly when I touch it? [closed]
I have a "Corn" LED light bulb very similar to this one on my bedside lamp:
It is one of these salt crystal lamps:
As you can see it has the salt crystal on top, then a part made of wood, ...
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Why does TCS3200 lose accuracy when the light source is too bright?
I have a custom proof-of-concept project to detect fluid color within a PVC tube coming out of a patient's brain and turbidity (a reduction in light passing through) using an Arduino micro, a TCS3200 ...
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What is the laser power and nm required to cut a row of paper with these specifications? [closed]
Here are my specifics. I am looking at quickly cutting a wet-paper-like material approximately 0.2 inches thick. The material stands up on its own and is separated approximately 0.33 inches apart each....
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Can a photon be modeled using AC driven electron and AC driven wire loop?
Can a photon ("electromagnetic wave packet") be simulated in software as an electron bouncing up and down (for the oscillating E field) and a loop of electrons with neutralized electrostatic ...
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Automatic on and off light strip [duplicate]
I am trying to make an led strip turn on and off automatically based on sunlight. So when it is dark the lights will be on full brightness and when it is daytime the lights would be off. The led strip ...
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Can someone help me with a LED light fixture puzzlement? [closed]
I have been buying and using LED bulbs from the Dollar Tree for many years.
I have never had an issue with them in the past. Just the occasional burn out in my home office fixture because it stays on ...
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What is the name of these old colored indicator bulbs and are they still manufactured?
As an electronics project, I would like to create a PCB that generates random blinking lights similar to the computer panel props featured in late 60s/70s era television series:
The scale is possibly ...
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Designing a DIY low level light therapy device (LLLT)
I am designing a low level light therapy (LLLT) device similar to the one in this video.
Mine will be smaller using twenty each (for a total of 40) of two kinds of 3W LEDs:
2.4V 0.6A -- 660Nm red
1....
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Can I use a handheld spectrophotometer to calibrate my TCS3200-based fluid color assessment system?
I'm trying to build a system that measures color and turbidity within the tube that exits a patient's brain. Using a TCS3200 sensor and an Arduino micro, and a custom-made housing to ensure a dark ...
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What component is missing?
I have an address sign that is supposed to light when it gets dark outside. The issue is the photodiode (assume that's what the part is) is broken and has broken off the board. I have tried connecting ...
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How supply an outdoor string light with 10 LED bulbs 0.8W?
I currently have a outdoor string light with 10 LED bulbs 0.8W powered by a 3.7V lithium battery and recharged by a solar panel (5.5V 295mA).
Over time the battery discharges and no longer works. I've ...
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How to bright up LED when it's dark without wasting battery energy?
I am trying to design night light LED that brights up when it's dark. I know a solution using transistor that "drains" current so LED has not enough to light up.
A current flow through ...
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Dimming light idea
I have this idea to dim a light. The problem is that my EBS simulation software won't allow me to see the actual result of the dimming. The only way to test it out is to physically construct the ...
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Error Indicator Light on Heater
I have a heater with a neon bulb wired in parallel with a safety cutoff switch. The full current of the heater goes through the safety switch. If the switch trips, wouldn’t the full current just go ...
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Usability of COB LED filaments as replacement for traditional filaments
COB LED filament household lightbulbs are a thing now. Can someone explain to me what limitations there are to using these COB filaments in car headlights? They emit a very similar light pattern if ...
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How open this Christmas light plug to change fuse? [closed]
I'm trying to get to the fuse in this plug (pictured below) and it looks like I'm going to break it instead. All the videos and instructions I've found show a different plug that it is very easy to ...
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NE555 + CD4017 Airplane Strobe Light with LDR
Engineers! I have built a simple airplane strobe light using NE555 and CD4017 in order to flash two LED in a different pattern. I have added an LDR resistor with a transistor in order to switch OFF ...
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Adding PPF/PPFD / Scaling
When considering PPF or PPFD, can you multiply the PPF of the light source by a factor (for example x100) and divide the calculated PPFD value by it to obtain the same results? In another way - is PPF ...
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Can someone help me to identify this 6-pin SMD IC?
Is anyone able to help me identify this 6-pin SMD IC, or know what it does? I've been googling for it but I'm unable to find it or figure out what it is from the markings on it.
As seen in the ...
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What is this white component in this emergency light?
I have an emergency light, which I opened up. I see there is a yellow cable going to that sot of electronic component (by 'L+'). Is this a light sensor?
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Replacing three-wire timed switch with a microcontroller
The building is surrounded by 6 lights and 4 buttons, 3 of which are illuminated.
Right now the circuit is managed by a Perry 1IT 1051. Here are the official schematics:
While I'm happy with the ...
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Making a flashlight watch
My son has a rare genetic disorder (nyctalopia) in which the rods in his eyes don't work and so he can't see anything in dim light. I've seen him very confused and scared in environments where I can ...
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What are LCD subpixels made of?
Just curious. I don't really need to know this level of granular detail for my job (AV technician) but in courses/articles about color LCD displays they explain everything... except what the red, ...
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Conversion of portable fluorescent to UV-C lamp
I am modifying an off-the-shelf portable fluorescent light to a UV-C light for use in field illumination. I found a 13W UV-C 4-pin bulb that is the same physically as the OEM fluorescent, so thought I ...
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OPT3001 - Read before Conversion in complete
What will happen if Light Sensor - OPT3001 conversion time field is set to 800ms but read request is set every 100ms. Unable to find/locate the info in Datasheet.
Additions Info:
Transparent hystersis ...
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RGB LED Selection and Perceived Brightness
I'm trying to design a smart light with 800-1000 lm white LED strings (warm+cool) and RGB, but I'm having a hard time comparing the luminous intensity or sometimes mcd ratings.
How can I select red, ...
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What is this light sensor part?
This light sensor off of my lincoln town car stopped working. It is supposed to turn on/off my headlights when it is bright enough outside. I don't know what this part would be and would love some ...
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How to add delay to circuit
I have this circuit where a switch is used to toggle between the blue and red LED.
How can I add a delay so that when an ON switch is tuned OFF the RED LED doesn't turn on immediately
If the switch ...
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LED limit to short pulse and high power
I’m studying the viability of a small footprint distance detector that relies on a LED, a photodetector and some lenses. It’s meant for a distance above 150m, where the light beam travel time is ...
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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 ...
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How does one dim very high LED loads with PWM?
Suppose we take a LED source that can be dimmed using PWM (i.e., by turning power on and off at high frequency). Dimmers exist for these sources up to, say, 5A at 24V. But what if I want to dim 10x ...
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Why don't these LED's work in parallel?
noobie here as will be obvious in the next few sentences :)
I have this strip of LED's Amazon LEDs. I thought/hoped that since each led has its own resistor that this would mean i could cut off ...
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IR LED Safety: Where does this OSRAM App note (AN090) formula come from?
The formula is from OSRAM application note AN090 "Eye safety of IREDs used in lamp applications":
$$ L_{ir} \approx \frac{I_e R(\lambda)}{Z^2} $$
In the app note, they don't give a reference ...
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What is the reason for some flashlights emitting light in a square shape?
Here's an image of a flashlight that produces light in a "square" shape:
What is the purpose of this square light pattern, and why was it designed as a square as opposed to the traditional ...
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How to replace TCRT5000 IR sensor with TCRT1000 IR sensor
I've got a pulse sensing circuit based on the TCRT5000 IR sensor. Its working fine and I can easily see the pulse when finger is placed. But I tried replacing it with the TCRT1000 but there is ...
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Which of these wires is positive and which is negative?
I know that in DC circuits the colour code is often (but not always) that red is positive and black is negative.
On this AC mains wiring the wires are blue and brown. Does anyone know which is which? ...
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What is the name of this connector and where can I find it?
Any ideas on where I can locate this connector? It is from a bike light and connected directly to 18650 battery. 3mm x 2mm with 4 holes, but 2 wires from the battery. On the motherboard the connector ...
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Christmas lights glow for hours despite being unplugged
I have a set of Christmas lights (the LEDs are red, green, blue and yellow) that I unplugged last night, and in the morning the bulbs continued to glow dimly but noticeably.
It seems like it's been ...
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Dry film PCB yellow light
I print out a negative on acetate paper, I stick it on a copper plate with dry film, and I press it with an iron. While doing these operations, we have to be in yellow light, what is the content of ...
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What powers an LED across an open switch?
Honestly, I just can’t seem to figure out how this switch works.
I have a light switch that incorporates an LED that is on when the light is off. The neutral is not connected to the switch. The switch ...
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Minimum light bulb wattage for solar simulator
I am trying to design a simple homemade solar simulator. I have picked metal-halide lamps as my light source.
To achieve an irradiance of 1000 W/m2, I don't know what wattage of light bulbs are needed....
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Light bulb as limit, to what is current limited to?
I was wondering, if I use a light bulb as a current limiter when working with some electronic device, in case of a short circuit - what determines the current that is allowed to pass to the electronic ...
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Powering 12 LED tea lights with recycled power adapter?
I have 12 tea lights that are each powered by a C2030 3 V battery.
Like many of us I have a box of various chargers and whatnot.
Is this as simple as finding one outputting 3 V and splitting it 12 ...
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Will 500 THz frequency glow antenna while radiating?
I read 700 nm wavelength is visible light, for which frequency is 429 THz. If we produce that frequency, whether antenna will be radiating visible light?
Correct me if wrong.
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