Questions tagged [light-sensor]

The Light Sensor is a passive devices that convert this “light energy” whether visible or in the infra-red parts of the spectrum into an electrical signal output.

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Calculate distance between two vehicles without using GPS

I am trying to understand if there is any way to measure the distance between two vehicles, possibly moving, without the aid of GPS. I want to measure a distance of more than 50 meters but less than ...
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2answers
209 views

Photodiode robust enough for laser?

I want to detect a laser using a normal photodiode (Datasheet), but I am not sure whether it is robust enough, as laser (lower than 5mW) emits high energy photons. Can I shine on such a photo diode ...
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4answers
444 views

Is there a light sensor that varies output with wavelength?

What components are sensitive to the wavelength (energy) of impinging light? I am wondering if there are any that have a reliable and detectable response to wavelength instead of just intensity. For ...
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136 views

Do flat distance lasers exist?

In short, I want to create a flat laser plane that knows where it's being penetrated. If flat distance lasers do not exist, what other options do? I considered using several regular distance lasers ...
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3answers
176 views

Reference for color sensor [closed]

I am trying to make a colorimeter using TCS3200 sensor and white LED light source. After weeks of research and understanding on how different white light sources work and what are the algorithms ...
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3answers
570 views

How to avoid LDR controlled light self-latching?

I am planning on using an LDR to turn on a LED light (700 lunes warm white fixtures), when the main light in the room gets turned on. But this LED light is pretty bright on its own. I think I will end ...
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4k views

What are the limitations of using a LDR sensor?

I have to explain limitations for a photoresistor/LDR . I've read the book, and searched online but find nothing. Can I get help with this ? Are things that the sensor can NOT do, which other tools ...
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3answers
112 views

Lux sensors with max. operating temperature of 90-100 deg C?

For my project, I need to observe the lux inside a double-pane window. Last time, I used 'Adafruit TSL2561 Digital Luminosity/Lux/Light Sensor Breakout'* but its recommended maximum operating ...
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4answers
285 views

LM393: Electronic Fry Counter

We're using an LM393 Light sensor and a laser transmitter used for counting the fry that will enter into our machine. The machine counts properly when we use an object like a pen or a stick in front ...
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2answers
1k views

How to stop a motor when car approaches wall - phototransistor?

In a school competition for my son, he wants to make a toy car that will stop before it hits a wall (before, not making an impact). It can go as slow as it likes and cannot be remote controlled. I ...
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1answer
501 views

Why would any smartphone need an ambient light sensor if it already has a front-facing camera?

Why would any smartphone (e.g. the Samsung Galaxy S5) need an ambient light sensor if it already has a front-facing camera? Surely it requires time and money for the engineers to design an ambient ...
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3answers
82 views

dc voltage control for LED lights?

I'm looking for a little bit of help on a project I'm working on. I need to find some way to make led light bars (18w and 120w) to automatically start out dim and gradually brighten to full ...
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2answers
69 views

How to measure body temprature and HBR with just one IR transmitter and receiver

I want to measure body temperature and heartbeat rate only with a IR receiver and transmitter. How could I do that? Is it an accurate method? Or I have to use IR temperature sensor for this.
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743 views

Can I use the IR break beam sensor outdoor/indoor for 4-5 meters range?

I need a sensor which can count a fast moving object. I am thinking to use IR beam break sensor. But, I think there will be a problem with the sunlight as the Tx-Rx will be 4-5 meters apart. I also ...
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1answer
160 views

BH1750 Sensor ICs - Block Diagram - Why it has capacitor connect output to input of OpAmp?

The image from BH1750FVI datasheet. http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1750fvi-e.pdf (page 4) I don't know why it has the capacitor connect output and input of ...
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2k views

Choosing resistance in series with a photoresistor for best light-measurement resolution

simulate this circuit – Schematic created using CircuitLab I have a photoresistor, R1, and as a voltage divider a fixed resistance, R2. There is a voltage of 5V over these two, and the voltage ...
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1answer
933 views

I need help with a simple IR circuit to control electromagnets

I have a project , I know what I want it to do but don’t know how or the components needed. I want this IR beam-break trigger to control two of these 12v magnets (.33A each). When the beam is broken, ...
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1answer
41 views

IR Light Transmission Delay Error

The following circuit consists of two IR (Infra-Red) LED diodes; one as light transmitter (IR1) and other as light receiver (IR2). They are spaced for approximately 4 cm, so distance is not the issue ...
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1answer
57 views

How to filter out certain wavelengths of light [closed]

I am trying to filter out certain wavelengths of light and I was wondering if there is a way that you can filter them out. I am using Silicon Photomultipliers (Linked below) and I only want to detect ...
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1answer
26 views

Phototransistor and Photodiodes capacitances when some in an array sense light

I'm using phototransistors to sense low speed data (about 7 bits a second). With one phototransistor and a 300K resistor, I found my sweet spot and can transmit correct data with lazer. I find if the ...
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1answer
67 views

Need a sensor for detecting the presence of someone like a door sensor we have in lifts/elevators

Door sensors used in elevators/lifts are very expensive and my budget is not that much. But I need a similar mechanism or solution to detect the presence of someone if he/she is standing in the given ...
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1answer
168 views

Kid's night light

I would like to make a more reliable nightlight for my daughter. I was using cheap solar string lights but they just don't last long enough or get enough sun on that side of the house. So I've ...
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5answers
676 views

What's causing a bad response time of a phototransistor at 100 Hz

I am working on a project that involves communicating with LEDs. I need to be able to detect the state of a light source that is flashing at about 100 Hz. I am using the phototransistor that comes ...
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1answer
77 views

How do I build a micro controller based laser detector

I want to build a laser detector using a photoresistor and a pen laser. Ideally, I would like to increase the surface area that detects the laser beam, perhaps through refraction or diffusion. I'm ...
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1answer
51 views

What material should be used for large-scale electron emission?

Photocathodes, to my knowledge, are usually used for precise and fast light-detection. But would they also be suited for the sole objective of ionizing the surrounding air? If no, what materials would ...
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1answer
294 views

Laser detector parts

I have been trying to find laser level detector components. I took apart one on hand, see what looks like basic photodiodes and a light tube. Note the 3 photodiodes visible in the center part. ...
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2answers
745 views

Sensing directional light

I am looking to detect the amount of light coming from a specific direction that lands in a specific area on a PCB. In my research, I have only found ambient light sensors and never any kind of ...
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1answer
407 views

Light Detector/Identifier circuit using photodiodes

I'm currently completing my final year project and am currently stuck going round in circles as how to complete it. To summarise: I need to design a circuit which is capable of IDENTIFYING a light ...
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1answer
92 views

Help Interpreting “Max light exposure” rating for TSL1406R

I've purchased a TSL1406 Linear Sensor Array to read the position of a laser dot. The "Absolute Maximum Ratings" section in the datasheet specifies "Maximum light exposure at 638nm" as 5 mJ/cm^2. ...
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2answers
82 views

Photoresistors detection

If I have a 2cm*2cm square and drill a really small hole in the middle thats barely visible for the human eye, and I place a photoresistor below , will the photoresistor be able to detect any light ...
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2answers
335 views

PIR sensor based LED light controller

I have a PIR sensor module based on BIS00001 IC. I am using the 3.3 VDC output signal of the sensor module to trigger an LED matrix using a low side NPN transistor and a current limiting resistor. ...
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1answer
101 views

photodiode, ldr and light source

I need to measure the red or green or blue component of a light source. Are there any resistor or diode with this specific capability? I found some diode with rgb filter, but i'd want to know if there ...
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2answers
68 views

Detecting object Water Reservoir

You have this large water reservoir, for example, a bathtub. How can you detect when an object is thrown (rock, etc) into a big water reservoir? Vibrating sensor, ultrasonic etc?
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1answer
937 views

Laser activated switch using a photo-transistor

I would like to make a laser activated switch using a photo-transistor or an LDR, by which I can switch off the lights in a room from a long distance. I just have to point the laser and it will detect ...
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0answers
42 views

How to deal with specular reflections from ultrasonic distance sensors

I am currently challenged with the following problem: I am given an autonomous robot which uses the HC-SR04 ultrasonic distance sensor to determine its distance to the robot driving in front. ...
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0answers
32 views

Choosing a camera for near-infra-red illumination analysis

Which parameters are important to look for in camera specs./data-sheets if it will be used for irradiance pattern analysis from near infra-red sources. Typical spectra range of interest is from ~700nm ...
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1answer
93 views

Relative responisivity of the VEML6040

I'm currently working a project involving the VEML6040 color sensor (Link to application note). I am reading through the application note and stumbled on the graph depicted below. As far as i ...
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1answer
56 views

How can you figure out what encoded signal my IR emitter should put out to register a hit on a laser tag gun?

I am using a 38kHz IR emitter, I've taken out the IR receivers on these guns and experimented to see if I am able to transmit a signal, it's working fine, however when I connect the IR sensor back in, ...
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2answers
75 views

Is it possible to detect specific UVB wavelength ranges using just a UVM-30A UV sensor or similar

Is it possible to detect specific UVB wavelength ranges using just a UVM-30A UV sensor or similar. The spec sheet for sensor GUVA-S12SD. Seems to indicate that it generates a specific current level ...
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1answer
64 views

Building a Meter to Measure UVB Radiation

I need to build this instrument for a science experiment related to vitamin D production. I understand that it is necessary to use a photo-diode that responds to UVB wavelengths only and that I need ...
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1answer
2k views

TSL2591 sensor value calculation

I bought an TSL2591 breakout board and wanted to write driver for my board. After looking at the documentation, i found that i cannot calculate the illuminance value (in Lux) as their was algorithm ...
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3answers
450 views

Ideas required to detect object position

I am trying to figure out the possible solutions for detecting the position of the object in the container. the below image is to describe the scenario. Object: spherical diameter: 5 - 7mm Type: ...
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3answers
264 views

How to control the brightness of an AC light bulb with the instant level of noise nearby

The device I want to make is simple to describe: a big red lightbulb, connected to the AC 110 / 220 V, stays dark when it's quiet in the room, starts lighting up somewhat if there's a moderate level ...
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1answer
50 views

Day-Light Sensing LED Light [closed]

I am looking for an example of a day-light sensing LED light, similar to https://www.evilmadscientist.com/2007/a-simple-and-cheap-dark-detecting-led-circuit/ but instead of turning on when dark, I ...
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1answer
267 views

Which one is better to build lux meter, either LDR or photodiode?

I want to add the lux meter to my application. My controller works with 3.3V and ADC max reading voltage is 1.2Vref. I tried with LDR but I'm not able to get accurate values and the values also not ...
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1answer
78 views

Why popular line detection use Infrared(IR) based sensor? [closed]

Popular line sensor use IR LED as transmitter and IR photodiode as receiver to distinguish reflective color such as white and less reflective color like black. Consider that infrared LED is hard to ...
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1answer
117 views

How do I build a Circut to create temperature changes in LEDs? Looking for a range of 3000 to 6,000 for photography? [closed]

I see commercial lights for photography that can change color in the range of 3-6,000 or tungsten to daylight values. These are not arrays of three RGB lights but rather single LEDs and the ...
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1answer
88 views

How to connect a 2 pin photodiode?

Initially, I have used 3 pin photodiodes, where the anode is connected to the resistor and has a wire which goes to group and the other goes to an analogue input to read the voltage. The cathode is ...
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1answer
393 views

opt 101P photodiode for light communication [closed]

The following is the circuit for Light communication using opt 101P photodiode. Connections are COM pin (pin 8), and pin 3(-V) are grounded. Input volatge(pin 1) Vcc = 9 V . OPT 101 has a photodiode ...