Light up in the dark

Why it’s here

Lower the light reading across the threshold and watch the lamp turn on.

How it works

Use an LDR divider and a threshold to switch a desk lamp. Only for the divider orientation used here. Reversing the divider reverses the direction. This guided model targets the original ESP32 and Arduino-ESP32 3.x; radio, acoustics, loads and mechanics are simplified.

Try it

1. Open this experiment
2. Lower the light reading across the threshold and watch the lamp turn on.

Connections

• GPIO 34 — LDR + 10kΩ divider, 3V3/GND
• GPIO 2 — Lamp LED through resistor

Example sketch

void setup() {
  pinMode(2, OUTPUT);
  Serial.begin(115200);
  analogReadResolution(12);
}

void loop() {
  int light = analogRead(34);
  digitalWrite(2, light < 1000);
  Serial.println(light);
  delay(50);
}

Check your understanding

Does a lower reading always mean darker?