Easy to Make LED Light Sensor

In this tutorial, I will give you a guide to how to make a simple LED light sensor. Whether your a beginner in electronics or already have general knowledge, this project will give you a hands on experience to expand your knowledge. By the end of this tutorial you will have a working LED which varies in brightness based off of detected light. Enjoy!

Materials list:

1. Potentiometer - 100k Ω
2. LDR
3. Resistor - 470 Ω
4. LED - 5mm
5. Transistor - 2n2222
6. Resistor - 1000 Ω
7. Circuit/Matrix Board
8. Power Supply - 6V

The photo above is a design I made in Tinkercad for the layout of the circuit which you can follow. once you understand it you can move on to actually making the design.

How the parts work:

LDR (Light Dependent Resistor):

The LDR changes its resistance based on the light level. If the light is bright, its resistance is lower while if the light is darker the resistance is higher.

Potentiometer:

The potentiometer is used to adjust the sensitivity of the circuit. By turning the knob, you can change the resistance, which changes the point at which the LED will turn on or off based off the light detected by the LDR.

Resistors:

Reistors limit the current going through the circuit to protect components like the LED and the transistor from getting too much electricity passing through them and short circuiting.

Transistor:

The transistor acts as a gate. It controls the current flowing into the LED. If the LDR detects low light (high resistance), the transistor is turned on, allowing current to go through the LED lighthing it up. When the LDR a detects bright light, the transistor stays off, and the LED remains off.

LED:

The LED lights up when the circuit is activated by the transistor, which is controlled by the light levels detected by the LDR.

Before starting to assemble make sure you have your workspace setup this should include:

1. A Soldering station (Flat even surface, Soldering Iron Holder)
2. Helping hands tool
3. Components and tools (Wire Stripper, Wire Cutter, Materials List)
4. Safety gear (Eye Protection, Closed Toe Shoes)
5. Power supply
6. Workspace cleanliness

Once you get all this set up your ready to start the circuit!

When you put your components in place you should also have 2 single threaded wires running down each side as shown in the video above. These will act as positive and negative sides. After that just put the components in place as shown in my photos. Make sure your components touch each other otherwise the charge will not go through.

Soldering your components is one of the most important parts of creating your circuit. When soldering make sure your in a clean workspace with the proper safety equipment present. It is important that you are precise while soldering as having a dry joint (components not touching) could ruin the entire circuit.

You also need to make sure you have your positive and negative wires running down the board. You can use a single thread wire which is where you connect your positive and negatives to the power source.

After you have finished your soldering, you can test your circuit! connect it to a power source and check if it works. the LED should get dimmer when you shine your light on it as shown in the video. If it does not work try checking for some of these problems:

1. Dry joints. (parts not touching eachother)
2. Turn the potentiometer.
3. Make sure the positive and negative sides are correctly placed.
4. Make sure the resistance levels are correct.