Difference between 2 pins and 3 pins?

Hi, I am building a light sensitive interactive installation. I am following this tutorial which uses 3-pins sensor but I only have 2-pins. What is the difference? Is there anyway that I can still use the 2-pins on the breadboard? Please advise. Thank you so much in advance!

Yes, connect the LDR between the Arduino analog pin and ground and connect a 10K resistor between the pin and Vcc.

The LDR and the fixed 10K resistor together form a "voltage divider". This will feed the Arduino analog pin with a voltage somewhere between 0 and Vcc, depending on the light level.

Take look at this from https://maker.pro/arduino/tutorial/how-to-use-an-ldr-sensor-with-arduino

  • The LDR is in series with a resistor
  • One leg of the LDR connects to 5V - connection 1
  • One end of the resistor connects to GND - connection 2
  • The connection between the LDR and the resistor is connected to the Arduino pin - connection 3

Can you see how the two connections of the LDR are used and how the circuit uses 3 connections

The 3 pin module that you have posted an image of is wired the same way except on a PCB

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