How to Make a Self-Lighting LED Circuit + Create a Housing

I made a circuit that activates whenever there is no light present to help with my room lighting and also with a switch in case I don't want to waste power. In addition, I created a 3D printed 'car' housing to house my circuit mainly for aesthetics.

Circuit Board Supplies

1. (07cm*09cm) perf board
2. 1k Ω resistor
3. 100k Ω resistor
4. LDR photoresistor
5. Electric cable rolls
6. 4x AA batteries(total power - 6v)
7. Battery Pack, (no bigger than 5.75*6cm)
8. Slide switch
9. Electric cable roll (different colours would be great to help with identifying positive(usually red) and negative(usually black) charges.)
10. 5mm Yellow LED (any colour is fine, I chose yellow because it changed car aesthetics from normal taillights)
11. BC108 Transistor
12. Breadboard (to test circuit without permanence IRL, not necessary)

Tools

1. Wire cutters
2. Insulation Tape
3. Wire strippers
4. Solder
5. Soldering iron
6. Soldering iron holder
7. Soldering Helping Hands (helps hold your circuit while soldering)
8. Safety Gear (Eye Protection, Closed Shoes)
9. Sponge to remove excess solder from the iron

3D Printer

1. Adventurer 5M Pro or any other 3D printer
2. Plastic or other materials e.g. resin for 3D Printing. PLA, ABS, PETG, PLA-CF, and PETG-CF are all accepted by Adventurer 5M Pro

Software

1. Autodesk Fusion 360 (to design circuit housing)
2. FlashPrint 5 (to send to 3d printer and further customization)
3. Tinkercad (to test the circuit online to see if it works)

Below are explanations for the parts within my product.

100k Resistor - Used to resist the voltage that is coming from the photoresistor to the light bulb to resist the voltage enough so that it doesn't exceed the capacity of the LED. 

1k Resistor - Used to provide resistance for the photoresistor to function so that there is no excess voltage that can damage it

BC108 Transistor - This is used to amplify the electrical current that is coming from the battery

Wires - Used for transferring electrical conduction within different components and is essential for the circuit. Covered with insulation to prevent electricity from leaking to other components through unwanted contact.

Battery pack - It is a 4*1.5V (AA) battery to provides a final V of 6V and is the power source of the whole circuit

LED - Is the output of the circuit and lights up when there is no light detected on the photoresistor, and diminished when there is light detected.

LDR - This detects when light is present or not present to make a closed or open circuit. When there is low light detected, the LDR decreases its resistance to the current flowing and therefore the current can flow through the circuit to the LED, lighting it up; when there is a bright light the LDR increases the resistance so that the current cannot flow to the LED, leaving it dim.

Slide Switch - When it is slid to one side, the electrical flow flows from the battery, through the switch and into the circuit, which powers the circuit. However, when it is switched to the other side, the circuit becomes open because the connection is broken, resulting in no current provided to power the switch. The battery connects to the outermost wire of the slide switch and the wire connected to the middle lane of the slide switch connects to the area in the circuit where the positive side of the batteries were supposed to connect to.

Modelling the circuit in Tinkercad before performing it in real life can be essential because it can ensure that the circuit will work properly and that mistakes can be avoided in real life that can be harder or more time-consuming to reverse, e.g. soldering, or dangerous, like unintended short circuits. The software is useful for me as, for the ideation design I chose, it showed me every time my light bulb was lighting up and the photoresistor was manipulating the light, and whenever it didn't I could be sure that there was a flaw in my component or wire layout and fixed it. It also showed me when there was a short circuit by illustrating the light bulb exploding signifying excess current so that I can modify the resistance or power travelling through the circuit accordingly. 

1. This test was done on an online simulation of a breadboard to make sure that the initial design of the circuit would work.
2. It was successful because the LED turned on with the correct resistance provided by the circuit and it was sensitive to changes in the photoresistor.
3. It initiated me to perform the next test on the breadboard. I used this as a layout reference for the rest of this project.

I had both 1k and 100k resistors needed, so I had a resistor that had bands of brown, black, black, brown, brown for a product of 1k ohms and another resistor with bands of brown, black, yellow and gold for a product of 100k ohms of resistance. The polarity of these resistors does not matter within the circuit.

For wiring, I used an electric cable roll to supply me with wires to use. The wires were cut using a wire cutter, and the rubber was chipped off at the ends of the wire using another tool called the wire stripper (some of which have a wire cutter included.) The wire should not be too long so that it doesn't make a mess in the circuit, but it should be short enough to reach the distance of two connected components. For breadboards, I simply connected a wire in a column and another wire in the same column on the next row to electrically connect these two wires as guided by my tinkercad design. For the perf board, however, I used solder to connect these wires(explained later), since it is more durable and provides a strong, permanent connection.

Using my online recreation of the Using the breadboard first allowed me to confirm further that my circuit would work before recreating it on a perf board. This is because, in real life, more problems can occur that can alter the flow of electricity in a physical circuit that aren't present in an online simulation, this includes the limits and capabilities of components like the light bulb and transistors as some may be worn out or built for different conditions. Wiring is also cleaner in the online simulation. In contrast, in a 3D environment, it can consume a lot more space and one can get an idea of how to design housing or manage the wires based on initial testing using a breadboard. The breadboard is better than using a perf board for testing because components and wires don't need to be soldered to connect, instead they are all connected through the interior of the breadboard and one needs to simply push the wire into a hole in the breadboard to lock it in place and connect it to the circuit and pull with minimal force to remove it. This can save time because the use of soldering and the reversal of soldered items using a perf board are a lot more time-consuming compared to the use of the breadboard, making it much more practical for testing.

1. This was done on the breadboard to ensure that all the components would work as intended in real-life
2. It worked as intended and prompted me to add a final permanence to the circuit by using a perf board.

Put on safety goggles and wear closed-toed shoes. On a flat surface, Connect your soldering iron and place it on a holder. Wet a sponge and keep it by the side. Grab solder and use wire cutters to cut it into small pieces to use, in addition, keep the wire cutter aside in case it needs to be used to chip off excess wire. Put the Helping Hands on a flat surface to support your circuit and then you can start soldering. To solder, heat the wire connection of multiple wires with the soldering iron and touch the solder to the iron until a ball is formed on the connection. Use the sponge to remove excess solder on the soldering iron. Finally, on connections that you think may be exposed to other metallic parts, use insulation tape to cover them in order to make sure that they don't connect unwanted currents together.

After testing the circuit on the breadboard and ensuring that it works, I connected each wire and those of each component to each hole of the perf board by soldering each hole to the wire under the perf board using a soldering iron and solder. This ensured permanence in the circuit while being strongly connected as the use of solder hardens to stay stronger than a breadboard and cannot be simply pulled away, all while providing an electrical connection between components since the solder that connects these components is electrically conductive. I soldered using a soldering iron to mould the solder onto the wire and its connected hole.

I followed the initial design I made in tinkercad exactly to map out onto this perf board and create it.

This was done on the final perf board to showcase that the circuit does work when connected with the solder and to show certain quality-of-life improvements such as the slide switch and soldered battery.

This test also worked, showing that I was able to create a circuit that matched my initial aim in the introduction

Here are some of the specifications that I could have used to create this car housing:

5.75 x 6.1 is for the battery pack 

9.05 x 6.9 is for the perf board 

Attached is an annotated diagram of all the measurements(in mm) I have used to create this housing. The design itself can be created in any way, however, if you want to get inspiration from my design you can use the exact measurements above. The only important things needed within this car housing present for all designs are the following:

1. It must have two holes/areas that can fit the perf board circuit and the battery pack in the car (9x7cm and 5.75*6cm respectively). Or, if your perf board and battery pack dimensions, account for those specific dimensions in your design.

The next step will include essential techniques I used in 3D Design to create my design. I used AutoDesk Fusion to create this 3D Design. There are many more tools in auto desk fusion that I did not use, however, if you want to elevate your model accuracy, you can research more on these.

At the top left of the screen, the icon above means to start a new sketch. It will prompt you to select a plane depending on which angle you want the sketch to be in. Also attached are a variety of shapes that you can create as a 2D drawing. These will be used to, in the future, transform into 3D objects for our model. These shapes can also be manipulated further which are also mentioned in future steps. Once finished with the sketch, click 'finish sketch'

Select the attached icon and then select your sketch to extrude it and give it height, making it 3D. This essentially creates a prism of any sketch.

Using the same extrude method, you can extrude a sketch into an existing 3D model to carve the sketch into that model. An illustration of this is attached.

An effective way to make certain models look more realistic is using the fillet feature. This takes any sharp edge and turns it into a rounded corner. This helped in making my car model look more realistic. Click the attached icon above which is located at the top of your screen and then select the edge you want to fillet.

On the top bar of your screen, click file and press export to export the model. Select the 3mf file name in the export menu since FlashPrint 5 supports this file type. In addition, you can also name the file however you want

Open FlashPrint 5, and on the bottom left of the screen, click the icon and select machine type - Adventurer 5m pro (or whichever printer you are using)

On the top of your screen press 'File' and 'Load File'. This will display the file in the grid. Make sure the file fits inside the grid so that it can be fully printed.

Next, we have to add supports to make sure the structures stay intact and don't fall apart. On the right of your screen, click the 'supports' icon (image attached), and click on 'auto supports' to add supports to the structure. In addition, you can mess with settings like pillar size, support type, etc. to change the layout of supports.

Click the 'Start Slicing' button, and click 'Slice' on the menu that appears. This translates the 3D Design into G-codes that the 3D Printer can understand. Connect to a specific Wi-fi connection that your printer has to be on its same network. Then click on the icon for connecting to the printer on the top of your screen(image attached) and enter your printer's IP address or scan a printer to connect to it. Click the connect button when done.

Finally, select the 'Send Gcode' button to send the file to the 3D printer to print. It should start printing at this stage.

Finally, with the 3D Print, use wire cutters to remove some of the supports that block the key designs of the model, e.g. for me it was the base and the window of the car.

Then I put the circuit in its designated area within the housing and tested it a final time.

Test: link