CdS cells are little light sensors. As the squiggly face is exposed to more light, the resistance goes down. When its light, the resistance is about ~1KΩ, when dark it goes up to ~10KΩ. To use, connect one side of the photo cell (either one, its symmetric) to power (for example 5V) and the other side to your microcontroller's analog input pin. Then connect a 10K pull-down resistor from that analog pin to ground. The voltage on...

When the future is dazzlingly-bright, this ultra-high-range luminosity sensor will help you measure it. The TSL2591 luminosity sensor is an advanced digital light sensor, ideal for use in a wide range of light situations. Compared to low cost CdS cells, this sensor is more precise, allowing for exact lux calculations and can be configured for different gain/timing ranges to detect light ranges from 188 uLux up to 88,000 Lux on the fly. The best...

This Photo Transistor Light Sensor  is a simple sensor that detects ambient light. It's kind of the opposite of an LED - when light hits the little chip inside, it induces current to flow from the long pin to the short pin. This sensor has a built-in optical filter (probably IR filter) so it'll do a fair job of simulating light levels as the human eye does.  To use, connect the pin connected to the 'thicker' part...

Your electronics can now see in dazzling color with this lovely color light sensor. We found the best color sensor on the market, the TCS34725, which has RGB and Clear light sensing elements. An IR blocking filter, integrated on-chip and localized to the color sensing photodiodes, minimizes the IR spectral component of the incoming light and allows color measurements to be made accurately. The filter means you'll get much truer color than...

Vishay has a lot of light sensors out there, and this is a nice simple lux sensor that's easy to add to any microcontoller. Most light sensors just give you a number for brighter/darker ambient lighting. The VEML7700 makes your life easier by calculating the lux, which is an SI unit for light. You'll get more consistent readings between multiple sensors because you aren't dealing with some unit-less values. The sensor has 16-bit...

This T-Slot Photo Interrupter with Cable is a simple plastic sensor with two elements - an IR LED and an IR photo-transistor, situated across a U-shaped gap. You can control the IR LED and turn it on to transmit IR light across the gap, to the detector on the other side. This makes it perfect for detecting when something is in the slot. When there's something blocking the light, the sensor turns off, when the object goes away, the sensor...

The LTR390 is one of the few low-cost UV sensors available, and it's a pretty nice one! With both ambient light and UVA sensing with a peak spectral response between 300 and 350nm. You can use it for measuring  how much sun you can get before needing to covering up. Unlike the Si1145, this sensor will not give you UV Index readings. However, the Si1145 does UV Index approximations based on light level not true UV sensing. The LTR-390,...

This is the BH1750 16-bit Ambient Light Sensor from Rohm. Because of how important it is to humans and most other living things, sensing the amount of light in an environment is a common place to get started when learning to work with microcontrollers and sensors. Should we turn up the brightness of our display or dim it to save power? Which direction should your robot move to stay in an area with the most light? Is it day or night? All of these...

Extend your light-sensing spectrum with this analog UV sensor module. It uses a UV photodiode, which can detect the 240-370nm range of light (which covers UVB and most of UVA spectrum). The signal level from the photodiode is very small, in the nano-ampere level, so we tossed on an opamp to amplify the signal to a more manageable volt-level. This sensor is much simpler than our Si1145 breakout, it only does one thing and gives an analog voltage...

The VCNL4040 is a handy two-in-one sensor, with a proximity sensor that works from 0 to 200mm (about 7.5 inches) and light sensor with range of 0.0125 to 6553 lux. We've all been there. That thing is  close but  how close? When you need to measure a small distance with reasonable accuracy, such as the rough height of particularly calm bumble bee, the VCNL4040 Proximity Sensor from Vishay can do that for you. If perchance you also...

The Adafruit AS7341 10-Channel Light / Color Sensor Breakout is a multi-channel spectrometer, which is a special type of light sensor that is able to detect not only the amount of light present but also the amounts of light within different wavelengths. This means that you can use it to detect much better than the human eye is capable of, what color or colors of light is present. The AS7341 packs within its 3x2mm footprint 16 different...

Add a teeny analog light sensor, the  ALS PT19  analog light sensor is a great way to upgrade a project that uses a photocell and needs RoHS compliance. Due to the high rejection ratio of infrared radiation, the spectral response of the ambient light sensor is close to that of human eyes. It's a pretty simple sensor - connect - to ground, + to 2.5V-5.5V or so to power it. Now measure the analog voltage on the OUT pin. That's...

The VCNL4010 sensor is a nice way to add a small-distance proximity sensor to your microcontroller project. For longer distances (in the range of cm, you can use a SHARP IR distance sensor, but those are only good if the object is over 10 cm away. The VCNL4010 is designed for much shorter distances, no more than 200mm (about 7.5") and under our experimentation we found it worked best at distances of about 10-150mm. It would be good for say...

The colors of the rainbow, so pretty in the sky Are also in this sensor, controlled by you and I! Detect trees of green, and red roses too with the new  Adafruit AS7262 6-Channel Visible Light / Color Sensor Breakout . This sensor from AMS has 6 integrated visible light sensing channels for red, orange, yellow, green, blue, and violet. These channels can be read via the I2C bus as either raw 16-bit values or calibrated floating-point...

IR sensor tuned to 38KHz, perfect for receiving commands from a TV remote control. Runs at 3V to 5V so it's great for any microcontroller. To use, connect pin 3 (all the way to the right) to 5V power, pin 2 (middle) to ground and listen on pin 1. It doesn't do any decoding of the signal, just passes the 'raw data' along. Check the TSOP38238 datasheet for more details We have a detailed tutorial with example Arduino &...

This breakout is chock full o' sensors! Add basic gesture sensing, RGB color sensing, proximity sensing, or ambient light sensing to your project with the  Adafruit APDS9960 Proximity, Light, RGB, and Gesture Sensor . When connected to your microcontroller (running our library code) it can detect simple gestures (left to right, right to left, up to down, down to up are currently supported), return the amount of red, blue, green, and...

Remember when you were a kid and there was a birthday party at the pool and your parents totally embarrassed you by slathering you all over with sunscreen and you were all "MOM I HAVE ENOUGH SUNSCREEN" and she wouldn't listen? Well, if you had this UV Index sensor connected up to an Arduino you could have said "According to this calibrated SI1145 sensor from SiLabs, the UV index right now is 4.5 which means I do not need more...

This T-Slot Photo Interrupter  is a simple plastic sensor with two elements - an IR LED and an IR photo-transistor, situated across a U-shaped gap. You can control the IR LED and turn it on to transmit IR light across the gap, to the detector on the other side. This makes it perfect for detecting when something is in the slot - when there's something blocking the light, the sensor turns off, when the object goes away, the sensor...

This little sensor is a great way to add UV light sensing to any microcontroller project. The VEML6070 from Vishay has a true UV A light sensor and an I2C-controlled ADC that will take readings and integrate them for you over ~60ms to 500ms. Unlike the Si1145, this sensor will not give you UV Index readings. However, the Si1145 does UV Index approximations based on light level not true UV sensing. The VEML6070 in contrast does have a real light...

This Reflective IR Sensor is a simple plastic casing with two elements - an IR LED and an IR phototransistor. You can control the IR LED and turn it on to bounce IR off objects to determine their reflectivity. White & light colored stuff will bounce the light, so  you can detect it. Black & dark colored stuff will absorb the IR light so that it isn't detected. Likewise, if something isn't in the way of the sensor, it...

This Reflective IR Sensor is a simple plastic casing with two elements - an IR LED and an IR phototransistor. You can control the IR LED and turn it on to bounce IR off objects to determine their reflectivity. White & light colored stuff will bounce the light, so  you can detect it. Black & dark colored stuff will absorb the IR light so that it isn't detected. Likewise, if something isn't in the way of the sensor, it...

The TSL2561 luminosity sensor is an advanced digital light sensor, ideal for use in a wide range of light situations. Compared to low cost CdS cells, this sensor is more precise, allowing for exact lux calculations and can be configured for different gain/timing ranges to detect light ranges from up to 0.1 - 40,000+ Lux on the fly. The best part of this sensor is that it contains both infrared and full spectrum diodes ! That means you can...

Discontinued - you can grab Adafruit VEML7700 Lux Sensor - I2C Light Sensor or Adafruit ALS-PT19 Analog Light Sensor Breakout instead!    Upgrade a project that uses a photocell with the GA1A12S202 analog light sensor. Like a CdS photo-cell, the sensor does not require a microcontroller, the analog voltage output increases with the amount of light shining on the sensor face. This sensor has a lot of improvements that make it...

This little sensor is a great way to add UVA and UVB light sensing to any microcontroller project. The VEML6075 from Vishay has both true UVA and UVB band light sensors and an I2C-controlled ADC that will take readings and integrate them. The sensor also comes with calibration registers so you can easily convert the UVA/UVB readings into the UV Index. Compared to our other UV sensors, this one actually does a pretty good job of getting accurate...

The pIRkey adds an IR remote receiver to any computer, laptop, tablet...any computer or device with a USB port that can use a keyboard. This little board slides into any USB A port, and shows up as an every-day USB keyboard. The onboard ATSAMD21 microcontroller listens for IR remote signals and converts them to keypresses, mouse movements, or even USB serial output. Infrared is our favorite wireless protocol - no antennas, certifications,...

New from Adafruit, we are taking our most popular sensors and making them easier than ever to use! This is the Adafruit STEMMA TSL2561 which takes our favorite lux sensor and gives you two ways to play: you can use alligator clips to connect the sensor to your Flora, Gemma or Circuit Playground, or plug-n-play with STEMMA cables or Seeed Grove cables Each STEMMA board has level-shifting and protection circuitry on the power supply and data lines...