{"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":30,"inventory_management":"shopify","inventory_policy":"continue","barcode":"","requires_selling_plan":false,"selling_plan_allocations":[],"quantity_rule":{"min":1,"max":null,"increment":1}}],"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"}