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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5answers
845 views

Thin wall to block LED light from hitting photodiode?

I'm designing a small heart rate sensor using green smd LEDs and a photodiode. The photodiode needs to measure the reflected light, and not direct light from the LEDs. The LEDs are near the perimeter ...
0
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1answer
39 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 ...
3
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1answer
99 views

555 timer delay circuit + light sensor?

I am quite new to electronics and I would like to combine these 2 circuits together so that during complete darkness on the LDR, the LED would turn on instantly and when light falls on the LDR there ...
0
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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 ...
2
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1answer
61 views

Ultraviolet sensor response curve

I did a search on "ultraviolet sensors" in this forum, and came up with only three results, so, it appears, that this has not been asked before. I have a hand-held ultraviolet light sensor from ...
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3answers
473 views

How to build a light sensor for PWM dimmed light (for comparison against CC dimmed light)?

I am working on a project in which I need to find a PWM duty cycle to dim an LED to the same brightness level as an LED being dimmed with CCR. Initially, I was considering using a camera for this: I ...
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2answers
545 views

ESP8266 detect LED flash with photoresistor Schmitt trigger?

I made some experiments with ESP8266 to detect when an external LED is on or off (I need to log this activity). This is the test-circuit I used till now: simulate this circuit – Schematic ...
0
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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 ...
2
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2answers
81 views

Light sensors sensitive enough to detect for PWM from CF and LEDs?

I have an extreme sensitivity to PWM light sources such as computer screens and light bulbs. This can make it very challenging to make a purchase as I end up having to do lots of guesswork with ...
2
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2answers
106 views

Very low current (<10 microamps) darkness detector circuit that turns off in light

I've made a device that lights an LED at a very low current (<10 microamps) as a very dim indicator for use in the dark. At its simplest, the circuit is a 3V coin battery + resistor (300K-1M ...
0
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1answer
927 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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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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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. ...
0
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1answer
25 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 ...
0
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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 ...
0
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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
83 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 ...
3
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4answers
933 views

How to tell how sensitive a photodiode is?

I am looking to buy some new photodiodes for a project. Currently, I have been using expensive photodiodes with a picosecond level rise and fall time and a very small area to pick up light. The ...
20
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7answers
1k views

Any better way to determine source of light by analyzing the electromagnectic spectrum of the light

Project overview I am tasked to develop a microprocessor based device that when shown a light upon, can determine the source of the light (Natural light, Flourescent Bulbs, LED Bulbs, Incandescent ...
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2answers
74 views

Photodiode in photoconductive vs photovolatic configuration

I want to use a photodiode to measure light intensity, but I am not sure if the photodiode should be used in photoconductive or photovoltaic mode. From my understanding the photovoltaic ...
1
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2answers
163 views

VL6180X ALS values soo small

I have bought VL6180X proximity sensor on breakout (Aliexpress) originally designed for use with arduino. I have tried it use with Raspberry Pi and STM32 (on STM32F429 discovery board). Sensor is in ...
4
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2answers
485 views

Are light dependent resistors stable wrt time?

This question specifically concerns my issues with an ORP12 like:- I've read the data sheet and I see that resistance changes wrt short time (15 sec). Also note 1 mentions 16 hours. But what happens ...
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3answers
401 views

How fast can we measure using IR sensors

Supposing I have an repeatedly object passing through IR sensors and I am looking at the output waveform. What is the maximum frequency the output waveform can have? I think this maybe related to the ...
1
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1answer
204 views

Sensor to distinguish between daylight and artificial light in a room?

is there a way to distinguish between daylight and artificial light in a room? I'm thinking my options are a light intensity sensor or a color temperature sensor. The sunlight is supposed to be much ...
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1answer
259 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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2answers
17k views

LED light bulbs flicker when switched off - where does the energy come from?

Outside my house, at the front, I have a set-up of 3 lights attached to the wall. These lights can be switched on using a switch inside the house. Furtermore, they are attached to an infra-red sensor ...
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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 ...
0
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1answer
92 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 ...
0
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2answers
68 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.
0
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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, ...
18
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2answers
17k views

High frequency blinking LEDs and sensor for that

I want to make LEDs blink rapidly. (more than 1000 blinks/sec., faster is better) First, I am curious that the common off-the-shelf LEDs have a capability of blinking with such a high frequency. ...
4
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1answer
7k views

What Colors or wavelengths are Photoresistors sensitive to?

Using a LDR or Photoresistor, are they more sensitive to one color or wavelength compared to another? Or are they consistent with any light? Why?
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3answers
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
260 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 ...
-1
votes
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 ...
3
votes
2answers
152 views

Switch triggered by flashing light

I'd like a simple switch that triggers when a flashing light is detected. Purpose is to open gate by flashing car headlights (say 3 times). I have looked at comparators and photoresistors and ...
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2answers
63 views

Simulating a pyroelectric sensor

I am building test rigs and need to trigger motion detectors remotely. I would also like to avoid using a light source. The devices I've encountered all use an Excelitas 968 pyroelectric sensor (http:/...
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1answer
449 views

Is Deuterium arc lamp a AC or DC light source?

I have created a prototype photo-detector circuit to use in spectroscopy. The micro-controller code take 120 A/D readings and then returns average. I have noticed that when I use visible light (...
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3answers
3k views

Designing a Light/Dark Sensor for motors, using Transistor and and LDR

I am working on some project for which I need to turn off a motor whenever it's dark. I looked around and found some light/dark sensing circuits. However, most of these circuits use an LED that ...
0
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3answers
111 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 ...
2
votes
4answers
555 views

Long range directional light sensing

For an outdoor system I'm designing, I'm looking for a sensor able to detect a signal light from a distance of 50-150 metres and provide an output to a low-end microcontroller (i.e. not enough ...
1
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2answers
1k views

Dark sensor using relay

Trying to develop a dark sensor. Have successfully made it but with a major problem. As you can see the circuit here: When the LDR is covered the LED lights up using the relay NO terminal. However ...
0
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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 ...
1
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2answers
1k views

Photoresistor LDR in parallel

I need to sense light in 50 different points, but i can only arrange them in parallel because i need to use only 2 wires (this is limited by the application constrains). I only need to know if any ...
2
votes
1answer
96 views

Will I detect any signal if I apply laser light on one of the two light sensors placed in a sunlight?

I am trying to make a counter which should work in a solar light. I am thinking to use two ambient light sensors placed close to each other and use a differential amplifier. One sensor receives a RED ...
0
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4answers
284 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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5answers
668 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 ...
0
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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 ...
0
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4answers
438 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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2answers
2k views

Confusing dark sensor circuit diagram

I recently bought a set of four "light-control sensor switch" from ebay (link). Circuit diagram below. I put the circuit together (it was a DIY kit) and connected a protected LED at the output. The ...