This post introduces the GL5537 LDR Photo Sensitive Resistor unit that can be used to detect the intensity of light. It will be updated from time to time when I stumble upon more relevant information. If you stumbled upon more relevant information, see mistakes or doesn’t understand anything, please feel free to comment at the end.
While I was busy upgrading my motion detection operated desk lamp project I was looking for something to add that can be used to determine the ambient light sensitivity in order to prevent the lamp from being triggered during the day. Now there seems to be many development modules available on the internet, but because I was looking for something small, fairly cheap and was already using an Arduino for the project, I had to go for something that can be easily incorporated. The GL5537 LDR Photo Sensitive Resistor unit was it!
It must also be said that there are many equivalents out there on the market. I chose the GL5537 LDR Photo Sensitive Resistor not only because of its availability and price, but also as a starting point to get some consistency when using it in my projects.
What is a photo sensitive resistor?
Photo sensitive resistors are also referred to as light-dependent resistors (LDR), photoresistors or photocells. A photo sensitive resistor is a light-controlled variable resistor where the resistance decreases with increasing light intensity and vice versa. In the field of microelectronics, the difference or the value of the resistance can be recorded and be used for output logic.
Photo sensitive resistors are widely used in toys, lamps, cameras and other industries, but are also perfect to use by microelectronic hobbyist and engineers.
What makes the GL5537 LDR Photo Sensitive Resistor so special?
GL5537 LDR Photo Sensitive Resistors are fairly cheap and easy obtainable. The can be bought in bulk. I got 20 from eBay with free delivery for about R18 (early 2016). You can also buy a bunch with together with other requirements (mentioned below) from Banggood.
They are a breeze to connect to a microcontroller such as the Arduino using an analog pin.
GL5537 LDR Photo Sensitive Resistor specifications
Max input voltage: 150 V DC
Max Wattage: 100 mW
Operating temperature: -30 ~ 70 °C
Spectral peak: 540 nm
Bright resistance (10 Lux) (KΩ): 20 – 230
Dark resistance: 2 MΩ
Response time: 20 ms (rise), 30 ms (fall)
Resistance illumination: 4
Breadboard friendly: yes
Pin size: male
- GL5537 LDR Photo Sensitive Resistors (get 10 here)
- 10 K ohm resisters (get 50 here)
- At least 1 additional (mini) solderless developing breadboard (or sommer get five)
- Some additional breadboard wiring (Arduino and Raspberry Pi compatible)
- Functional Arduino connected to a serial monitor. I’ll be using an Arduino Nano (buy one Arduino Nano V3 w/ cable | buy one Arduino Nano V3 w/o cable | buy 5 Arduino Nanos w/o cable).
To get started with GL5537 LDR Photo Sensitive Resistor related projects you will also need some resisters. I also recommended to get some 10-20k ohm resistors (higher values gives higher/(more sensitive?) readings. Readings can be soft edited.