Light Dependent Resistors (LDRs) are little light sensors, and this is a BIG pack of 5 of them! As the squiggly face is exposed to more light, the resistance goes down. When it's light, the resistance is about 5-10K ohms, when dark it goes up to 200K ohms. These are the same KLDRs we use in our popular Edukit #2 Sensors. To use, connect one side of the photocell (either one, it's symmetric) to power (for example 5V) and the other side to your microcontroller's analogue input pin. Then connect a 10K pull-down resistor from that analogue pin to ground. The voltage on the pin will be 2.5V or higher when it's light out, and near ground when it's dark. Specification * 5mm Diameter * Resistance Decreases as the Light on the Device Increases * Dark resistance: 1M ohm * Resistance @ 10 Lux: 10-20k ohm * Resistance @ 100 Lux: 2-4k ohm * Max. voltage: 150V peak AC or DC * Power dissipation: 100mW * Lead pitch: 3mm * Operating temperature: –30°C to +70°C https://elecena.pl/product/22717084/ldr-light-dependent-resistor-5-pack-discontinued 2023-03-07 https://elecena.pl/product/22717084/ldr-light-dependent-resistor-5-pack-discontinued 2023-12-27 https://elecena.pl/product/22717084/ldr-light-dependent-resistor-5-pack-discontinued 2024-09-19 https://elecena.pl/product/22717084/ldr-light-dependent-resistor-5-pack-discontinued 2024-11-29 https://elecena.pl/product/22717084/ldr-light-dependent-resistor-5-pack-discontinued 2024-11-30 https://elecena.pl/product/22717084/ldr-light-dependent-resistor-5-pack-discontinued 2025-11-28 https://elecena.pl/product/22717084/ldr-light-dependent-resistor-5-pack-discontinued 2025-11-29