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{"id":4333705625718,"title":"Adafruit Photo cell (CdS photoresistor)","handle":"adafruit-photo-cell-cds-photoresistor","description":"\u003cp\u003eCdS 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.\u003c\/p\u003e\u003cp\u003eTo 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 the pin will be 2.5V or higher when its light out and near ground when its dark.\u003c\/p\u003e\u003cp\u003eCdS photocells are not RoHS compliant, so if you need something equivalent but RoHS compiant, check out the photo transistor.\u003c\/p\u003e\u003cp\u003eFor a full tutorial with wiring diagrams, code examples and project ideas, please \u003ca href=\"http:\/\/learn.adafruit.com\/photocells\" target=\"_blank\"\u003eread the photocell tutorial page\u003c\/a\u003e!\u003c\/p\u003e","published_at":"2020-04-27T20:21:49-04:00","created_at":"2019-11-05T15:36:59-05:00","vendor":"Adafruit","type":"Adafruit","tags":[],"price":90,"price_min":90,"price_max":90,"available":true,"price_varies":false,"compare_at_price":95,"compare_at_price_min":95,"compare_at_price_max":95,"compare_at_price_varies":false,"variants":[{"id":31088793911414,"title":"Default Title","option1":"Default Title","option2":null,"option3":null,"sku":"K479","requires_shipping":true,"taxable":true,"featured_image":null,"available":true,"name":"Adafruit Photo cell (CdS photoresistor)","public_title":null,"options":["Default Title"],"price":90,"weight":0,"compare_at_price":95,"inventory_quantity":15,"inventory_management":"shopify","inventory_policy":"continue","barcode":"","requires_selling_plan":false,"selling_plan_allocations":[]}],"images":["\/\/cdn.shopify.com\/s\/files\/1\/1749\/9663\/products\/161-00.jpg?v=1572986219"],"featured_image":"\/\/cdn.shopify.com\/s\/files\/1\/1749\/9663\/products\/161-00.jpg?v=1572986219","options":["Title"],"media":[{"alt":null,"id":5545439428726,"position":1,"preview_image":{"aspect_ratio":1.332,"height":728,"width":970,"src":"https:\/\/cdn.shopify.com\/s\/files\/1\/1749\/9663\/products\/161-00.jpg?v=1572986219"},"aspect_ratio":1.332,"height":728,"media_type":"image","src":"https:\/\/cdn.shopify.com\/s\/files\/1\/1749\/9663\/products\/161-00.jpg?v=1572986219","width":970}],"requires_selling_plan":false,"selling_plan_groups":[],"content":"\u003cp\u003eCdS 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.\u003c\/p\u003e\u003cp\u003eTo 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 the pin will be 2.5V or higher when its light out and near ground when its dark.\u003c\/p\u003e\u003cp\u003eCdS photocells are not RoHS compliant, so if you need something equivalent but RoHS compiant, check out the photo transistor.\u003c\/p\u003e\u003cp\u003eFor a full tutorial with wiring diagrams, code examples and project ideas, please \u003ca href=\"http:\/\/learn.adafruit.com\/photocells\" target=\"_blank\"\u003eread the photocell tutorial page\u003c\/a\u003e!\u003c\/p\u003e"}

Adafruit Photo cell (CdS photoresistor)

Product Description

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 the pin will be 2.5V or higher when its light out and near ground when its dark.

CdS photocells are not RoHS compliant, so if you need something equivalent but RoHS compiant, check out the photo transistor.

For a full tutorial with wiring diagrams, code examples and project ideas, please read the photocell tutorial page!

SKU: K479
$0.90 $0.95
Maximum quantity available reached.

Dimensions:

  • Length: 4.46mm/0.18in
  • Width: 5mm/0.20in
  • Height: 2.09mm/0.08in
  • Weight: 0.25g/0.01oz

Revision History:

  • As of Dec 15, 2019 the resistance range has changed to 1K-10K