Arduino Lab 7: Night Light

Background: Patients may need to get around their room at night, so having an automated nightlight system can be helpful.

Goal: Using a photocell, turn on an LED when it gets dark.

 

Circuit Setup

• Materials
  • 1x Arduino
  • 1x Photocell
  • 1x LED
  • 1x 220 Ohm resistor
  • 1x 10k Ohm resistor
• Setup
  • LED - connect the LED to digital pin 2 via 220 Ohm series resistor as we've done previously.
  • Connect photoresistor between 5V and A0.
  • Connect 10 kOhm resistor between A0 and GND.

 

Lab Instructions

• Detect the ambient brightness with a photocell. Turn on the night light (external LED) if it gets too dark.
• Use Serial.println() to print analogRead() values. Block the light and determine a good threshold value.
• Once the value is below the threshold, turn on the LED.
• Stretch Goal: Look up how to use analogWrite() to control the brightness of the LED in the components section.