Questions tagged [ldr]

A light dependent resistor (LDR) is a resistor where the resistance decreases with increasing light intensity.

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2answers
62 views

NE555 LDR threshold voltage

The problem is that when I set the LDR on my car and stop for a short time near street lighting my headlights from the car are switched off. I made a circuit simulation, when I click 4 times for the ...
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1answer
126 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 ...
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1answer
56 views

LPC1768 - Green LED when LDR sees light, Red LED when LDR is covered

I have been trying to achieve a task I am working on and I believe I am almost there. It successfully changes colors whenever I cover it but when it does, the red LED keeps blinking instead of it ...
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1answer
50 views

LDR breaks over time what to do?

http://cactus.io/hookups/sensors/light/ldr/hookup-arduino-to-ldr-sensor I have the following circuit which was running for a long time but at one point something broke and it started producing high ...
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1answer
94 views

NE555 and LDR circuit diagram

I have modified a schematic for my project with the following image: Instead of a 20K potentiometer, I use 100K for more precise adjustment. Do I need to add a disk capacitor of 10nf or 100nf to Pin ...
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1answer
57 views

How to find the best way to fade in/out?

I have a bunch of these PAR lights below. They work with DMX and have per LED PAR 3 red, 3 green, 3 blue and 3 white LEDs. I can set the value for the red, green, blue and white lights independently (...
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1answer
75 views

Voltage divider for ADC

Can anyone tell me why we use a voltage divider circuit with an LDR for an LDR robot? For example, why can't we directly take the LDR output and feed it to the ADC port in an ATmega controller? Why ...
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2answers
100 views

Calculating resistor values for a Schmitt Trigger and LDR circuit

I am trying to make a light sensing circuit which has hysteresis. I want an op-amp (LM358) to output logic 1 (12v) when the light level rises above 250 lux, and output logic 0 (0v) when the light ...
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1answer
35 views

Energia/MSP-EXP432 Issue: Analog In Pin removing voltage from Voltage Divider

In the circuit below, I want to measure the voltage going to the ADC (output from the voltage divider consisting of a fixed resistor and photoresistor) using an MSP-EXP432; however, the MSP-EXP432 "...
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1answer
63 views

MSP-EXP432 “Analog In” pin taking voltage from circuit [duplicate]

I am building a circuit consisting of a voltage divider (with a fixed resistor and a LDR or photoresistor) outputting voltage to an ADC. I want to measure the voltage going to the ADC using an MSP-...
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1answer
34 views

The 7-segment LED display is too dark when connect to a auto dimming circuit

I'm using the below circuit to build a auto dimming circuit. I was fine when I only use one 7-segment led, but when I connect more 7-segment led (parallel to L1) the light intensity is very low. How ...
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2answers
69 views

Device that transmits signal to computer [closed]

How would I be able to send a notification or email/msg of some sort to my computer after an event has taken place from elsewhere. To be more specific, when a tripwire is tripped, (LDR/Laser beam) how ...
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1answer
2k views

Please help me understand the following light-controlled relay circuit

I used the following circuit to control the outdoor light, and it works as I wanted. I am trying to understand the circuit and it looks like a comparator circuit, but I don't understand the use of ...
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2answers
84 views

Measure laser with photoresistor (LDR)?

I want to make a simple setum, where I can measure the opacity of air. I want to use a simple laserbeam, which I shoot across the room, and on the other side I want to measure how much is blocked/...
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0answers
124 views

How to identify different LDR photoresistors that have been mixed together?

I purchased a variety pack of LDR photoresistors from eBay which includes GL5506, GL5516, GL5528, GL5537, GL5539. The problem is that they all came in the same little bag and are visually identical. ...
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1answer
298 views

How to use multiple LDR to trigger a led? [duplicate]

Whats the best way to use multiple LDRs to power up an LED? Currently I’m using one LDR which turns on an LED when it senses light. But now I want to use three LDRs (at different locations) to trigger ...
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2answers
75 views

Light-activating a motor [duplicate]

I have an LDR and it reads higher than 17K ohm when the lighting conditions meet my requirements. I wish to be able to activate a vibrator motor (coin type 3 Volts) when the LDR has a resistance ...
1
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1answer
139 views

Arduino and car's 12V switch

I'm trying to control my headlights with my Arduino and a LDR. For this I will use the Arduino as a middle man between the lights switch and the actual lights. The switch has three positions OFF / ...
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2answers
267 views

Chicken coop door opener circuit

I'm designing a circuit that will open a chicken coop when the sun comes up. I've attached a bungee cord to the door which opens the door when a pin is released. This pin is released by a car door ...
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2answers
172 views

LDR issue interfacing with ADC [closed]

simulate this circuit – Schematic created using CircuitLab I want to read the voltage values of LDR (0-5V)but my desire range is less ( 1-3V) through ADC of 10-bit,but i am getting Clipped ...
0
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1answer
74 views

Understanding the circuit

I am a beginner electronic student and I know this might sound a bit easy for most of you, but I would like to understand the role of the components used in this circuit - it's an LDR-Controlled DC ...
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4answers
489 views

How does this LDR controlled light work?

Consider: The circuit here works based on the resistance of the LDR. I don't understand how it exactly works. It's said when the resistance in the LDR is high, current flows through R2 and the base ...
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2answers
172 views

Draw a circuit with a voltage divider, two comparator ICs, LDR sensors

I got this last question to practice for my exam and I got stuck. The question is draw a circuit with a voltage divider circuit, two Comparator ICs, LDR(Light Dependent Resistor) sensor Outputs: ...
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1answer
305 views

Use of transistor for switching the led

I have been trying a lot to get my circuit work. I want the led to light up when the LDR receives no light and vice versa. I have found that the LDR offers the resistance of approximately 6k ohms when ...
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2answers
307 views

Can I use a capacitor to power an Arduino for 5 minutes after the power has been cut?

I'm working on a simple setup using an Arduino Nano to automate the switching of my car headlights when it gets dark. I am happy with how to program the Arduino & LDR use and coding, it will be ...
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1answer
32 views

Photoresistor Night Switch

I have a problem regarding the schematic from the link below. I made the schematic from this link, at figure 5:http://www.nutsvolts.com/magazine/article/light-sensitive-circuits The problem is that ...
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0answers
164 views

Combining Dark Activated Circuit and Time Delay Off using 555 Timer

I'm currently working on a project. My project is a museum laser security system. In this circuit, if a thief touches a laser, the DAC will be activated because the laser that is hitting the LDR will ...
0
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1answer
343 views

Light Activated Switch Circuit with delay

In reference to this circuit: Photoresistor snap-on/off switch. If I wanted to add a small delay so that the circuit doesn't immediately turn then and off if the ambient light temporarily dips below ...
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1answer
541 views

Can LDR be affected by temperature?

I have an outdoor setup with arduino monitoring light sensitivity to turn on and off some lamps. https://diyhacking.com/arduino-ldr-sensor/ This started misbehaving couple of weeks ago and I wonder ...
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1answer
155 views

How to allow current over a certain voltage

I am new on electronics and i was practicing on transistors. I have a working circuit below. The LDR I use allows current and letting LED smoothly based up to amount of darkness. The Voltage after 2.3 ...
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1answer
293 views

How to make my automatic night light circuit dimming?

I am working on a project named as automatic night light.The idea is simple; LEDs are on when there is dark then LEDs turn off when the circuit detects light. However I have constructed the circuit I ...
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1answer
3k views

Light Dependent Resistor Photoresistor LDR: gl5516 vs gl5506

What is the difference between gl5516 and gl5506? (in a SIMPLE way)
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2answers
83 views

LDR Photoresistive Track

I completely understand the working principle of light dependent resistor. But there is one thing I am bothered about: Does the LDRs surface has to be equaly illuminated upon all its surface/upon all ...
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1answer
669 views

Arduino analog pin doesn't read correctly without connecting to gnd and Vcc of arduino

I'm using an LDR (photoresistor) with arduino and i have the following two cases: Case 1: I connect the input of LDR to Vcc of the arduino, The ground of the LDR to the ground of the arduino and the ...
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3answers
1k views

measuring time between extremely fast laser beam breakage using LDRs

I am conducting a scientific experiment to approximately measure the entering velocity and the leaving velocity of a magnet through an electromagnetic coil. Beside the coil are two lasers and two ...
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2answers
182 views

How to replace an LED with a diode and stop LED after timer ends?

So I have been working on this circuit that basically will activate an LED when the lux levels drop low enough. The time that the LED will remain active for is determined by VR4. I'm having two issues ...
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3answers
80 views

Can I expect SMD components from a same manufacturer to be identical?

I'm working on a project which requires at-least 2,000 ambient light sensors, and instead of using a microcontroler to manage and monitor the whole system I just want to amplify the output of sensors ...
3
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1answer
510 views

Help identifying two lead component with glass cover and serpentine trace under it

I ordered an IR pair of components from Amazon and received this which I do not think is an IR emitter or receiver. Does anyone have any ideas to what this component is? I could not find anything by ...
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2answers
224 views

Photo Resistor to Complete Circuit in Light

I am trying to create a very simple circuit using a CDS photo resistor. The situation is simple, I need a circuit to be connected when its light, disconnected when its dark. The photocell will sit ...
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1answer
292 views

LDR / photoresistor issue: resistance is constant in different light conditions

I have installation with Controllino mini, it's essentially an ATmega328, and with 6 LDRs and 6 lasers, creating laser rays/barriers. The system acts as a lasers labyrinth for entertainment purposes, ...
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2answers
360 views

Dark sensor - need 500mA output

Here is my dark sensor circuit (below). However, my output current is very low. I get a maximum of 150mA to drive my strip LED. But I require atleast 450mA of output current. I have tried many ...
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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 ...
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0answers
437 views

Reading an LDR array with a Raspberry Pi

I am trying to repurpose a replica GPO 746 using a Raspberry Pi, however the rotary mechanism is rather different to that in an original 746. The circuit has 12 LDRs arranged in an array (3 columns, 4 ...
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1answer
228 views

Does an LDR age?

I have had a twilight switch lying in my basement for 5 years after it was used in my garden for about 5 years. This week I took it apart to convert it for (solar) use from 230VAC to 12VDC. What is ...
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3answers
301 views

LDR working differently than usual

I observed something different in LDR (Light Dependent Resistor) today. I made a "magic" LED circuit such that when lights are off, the LED glows, else when the lights are on, LDR creates resistance ...
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3answers
3k views

What's the role of the transistor in this circuit? [closed]

So I have made this circuit for my project. (Instead of that variable resistor, I have used a single 1k ohm resistor) I know that a transistor can work as a switch and amplifier, but in this circuit, ...
0
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1answer
629 views

How to make the LM339 IC source current on its output pins instead of sinking current?

I know that the LM339 Comparator IC has a current sinking output. I made a small night lamp with the help of a LDR and an LM339 comparator IC. It worked properly. The LDR connected to the inverting ...
4
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3answers
1k views

LM339 Comparator IC is not responding to any input

I came into Electronics through Arduino, so pardon me if my knowledge about non-Arduino circuits is somewhat silly. I am preparing a small electronics project for my school with LDRs to detect light ...
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3answers
328 views

Light Sensitive One Pulse Activated Switch

Hello I planned a light sensitive one pulse activated switch to know when water tank is completely filled and to turn the water pump off using a relay until I reset the circuit using its N/C Switch. ...
0
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1answer
2k views

How to calculate the value of the fixed resistor in a light dependent voltage divider?

I have made, what I thought would be a simple circuit, an LED night light. The power source is 5V@1A. The schematic is below: simulate this circuit – Schematic created using CircuitLab The ...