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LDR 20 mm (Photoresistor)

LDR 20 mm (Photoresistor)

🌙 20 mm LDR (Photoresistor) – Large Surface Light Sensor

A larger 20 mm CdS photoresistor that offers improved sensitivity thanks to its increased sensing area. Excellent for light detection in robotics, automation, smart lighting, and educational electronics.

📊 Technical Specifications

ParameterValue
Diameter20 mm amazon.com+13microohm-eg.com+13goldsupplier.com+13
Spectral Peak~560 nm (green light sensitivity)
Light Resistance10–20 kΩ at ~10 lux
Dark Resistance≈2 kΩ (visible light), several MΩ in total darkness
Max Voltage500 V DC
Max Power500 mW
Response Time~30 ms rise/fall
Operating Temp. Range–30 °C to +70 °C
ConstructionEpoxy-coated, through-hole package
Model ExamplesGL20528, GL20537, GL20516 series

🔧 Key Features

  • Large sensing area (20 mm) for better light detection performance

  • Fast response and high sensitivity

  • Durable epoxy coating and stable spectral sensitivity

  • Multifunctional: perfect for night lights, streetlight controls, automatic doors, flame detection, smoke alarms, etc. amazon.com+13compoindia.com+13robotrybd.com+13

📡 Arduino Wiring Guide

Use LDR in a voltage divider:


CopyEdit
5 V ── LDR ── A0 ── 10 kΩ ── GND

Sample Arduino Code:

cpp
CopyEdit
const int LDRpin = A0;
void setup() {
  Serial.begin(9600);
}
void loop() {
  int val = analogRead(LDRpin);
  Serial.println(val);
  delay(500);
}

This setup helps create light meters, auto LED switches, and other light-based systems roboticsdna.in+14microohm-eg.com+14reddit.com+14.

📱 App & Project Ideas

Combine with an ESP8266/ESP32 or HC-05 to:

  • Send light data to Blynk or MIT App Inventor

  • Build IoT dashboards showing ambient light levels

  • Trigger smart lights or notifications remotely

▶️ YouTube Tutorial (copy-friendly)

https://www.youtube.com/watch?v=XwJQJnY6iUs

(Arduino & LDR Lesson #27: wiring, code, serial monitor) reddit.com+1protosupplies.com+1igelectronics.com+14microohm-eg.com+14compoindia.com+14

📄 Datasheet & References

Detailed datasheet for measurements and performance characteristics:

20 mm GL20528 (and related) LDR Datasheet en.wikipedia.org+13protosupplies.com+13goldsupplier.com+13

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LDR resistor