Introduction: Crossing With Traffic Lights for Kids
Today I want to show you my recent project - small crossing with traffic lights for kids. It must be designed for play with little cars and additionally help to learn basic rules of traffic lights. One of main assumptions of project is that this project has limited budget. So I tried to use as many parts I have on hand. Some of them are used, some of them are new. I didn’t pay attention on details, sometimes you’ll find this project a little bit messy. But remember that this is not important. Key thing is to have fun and create something from scratch.
So let's get started!
Step 1: Materials
Most of parts for this you can find in your house or buy in a local hardware store. Electronics stuff was purchased on Aliexpress.
List of materials:
- plywood sheet 40x40 cm (or more), thickness 1 cm,
- plastic tube fi 12 mm
- wood stick half round
- wood stick rectangular
- plexi sheet 3 mm thickness
- alu profile ramp shaped
- hot glue
- universal glue
- black paint
- white paint
- blue or any other color (different than black :))
- duct tape
- arduino mini pro
- addressable LEDs strip (WS2812b) - 60 LEDs/m type of strip
- rocker switch ON-OFF
- 3 x toggle switches
- 3 x 470 Ohm resistors
- 4 x 10k or 15k resistors
- some piece of bread board
- wooden box
- plastic cover
- 6 wire cable
- ribbon cable (different colors)
Step 2: Building the Raw Crossing
Draw on plywood crossing draft with a pen. Depending on plywood size you’ll need to cut rectangular wood strip into smaller parts which together will make a big cross. They will be crossing curbs. Sand them with sandpaper. Paint them with white color. Let them dry.
Cut ramp alu profile according to your road width. In my case it was around 12 cm. Grind all sharp edges.
Mark on plywood where you want to drill holes for tiny traffic lights. I used 12 mm round plastic pipe so hole should also be 12 mm fi. There will be 4 holes and additional. Drill additional hole for wires. In my case it has "bean shape".
Step 3: Building Traffic Lights
Now we need to prepare the lights. Get WS2812b LED strip and cut 3 LEDs segments. Solder wires to the end which has arrow pointed inwards. In my case I had some old wires but all were gray, so I additionally marked its opposite ends with appropriates signs to know where is plus, minus and digital. If you have colored wires there is no need to do it.
Light need to be diffused a little bit so I’ve cut small plexi rectangles (5 x 2 cm) and sand them with at sandpaper. You should use micro grit sand paper minimum P400. In my case it was P500.
Cut plastic pipe in 8 cm sections. Cut half-round wood stick in 12 cm sections. Sand endings of pipes and wood sticks with sand paper. We don’t want to hurt children playing with sharp edge.
Stick LED strip onto half-round wood stick, pull wires through plastic pipe and put stick inside.
Protect solder pads with hot glue, add some glue inside the pipe in both ends. Apply plexi rectangle on LED side of stick and add some hot glue from the back. Your traffic light sign is almost ready.
Step 4: Wiring Traffic Lights
Cut prototype pcb, solder 4 resistors 470 Ohms. To each resistor solder digital wire. Now solder all plus and all minus wires to prototype pcb. Cut 1 m of 6 wires cable and solder wires to plus, minus and 4 other wires to another resistor ends. Protect PCB with hot glue. I connected it to Arduino just to check if ever light is working. It was done with test program which blinks every LED with 1 s frequency.
All wires which are on the bottom side were protected with duct tape.
Step 5: Painting, Installing Lights
Paint plywood with black color (street) and another color (corner fields). In my case it was blue. Let it dry, if necessary put another layer of paint.
Stick round adhesive paper on traffic light signs to cover area of LED and protect it against paint. Next paint with black color traffic light signs. Let them dry and install them on plywood. You can add a little bit universal strong glue inside holes.
Drill or cut hole in the little enclosure. Install it on plywood and put resistor pcb inside.
Stick white curbs on crossing. Last step is to paint with white color road surface marking. You can use for that protecting painters tape.
Install alu ramp profile with screws. Before that I put some hot glue on sides to seal empty space, and paint its ends with white color.
Step 6: Building Control Box
Control Box will contain switches which will do different functions. I will describe them later on. So I used wooden box which I bought in hardware store. I drilled 3 holes (6 mm) on the top and 1 on the side (around 15 mm). I painted box with blue. You can choose different color if you want.
Next I installed all switches – 3 toggle switches for changing modes and 1 rocker – power supply on/off. One switch of the top has fancy cover plate. This will be special switch. I soldered pull down resistors to connectors and plus and minus lines (according to schematic). Resistors are protected with insulation shrink tube.
Now it is time to connect everything to Arduino. I used to control LEDs outputs 6,7,8,9. Inputs form switches will be 2,3,4. Details are on schematic. We need to have power supply. For this 3 AA batteries will be ok. So I hot glued battery holders. Because I have two of them I needed to connect them in series. After soldering check output voltage to make sure that you connected everything in a good way. Power on/off switch will break plus line so I soldered plus wire.
Step 7: Programming Arduino
To program Arduino Mini Pro I use USB RS232 FT232RL converter. You connect those device in the way shown below:
You can find program attached to this project. All wiring and connections are on the schematic. Note that I used 3 batteries AA to get 4,5 V power supply voltage. Although Arduino can be powered with higher voltage f.ex. 6 V (4 AA batteries), addressable LEDs WS2812b can be damaged with voltage higher than 5,3 V. Keep it in mind if you want to use different source of energy.
Step 8: Functionality
Let me describe the functionality or Control Box.
Witch switch no 1 you can change automatic mode to manual mode.
Automatic mode means that lights are changing continuously with programmed routine. We have 4 basic states of lights: green (you can go), red (you need to stop), yellow (you're about to stop), red-yellow (you're about to go). And all lights are working automatically. This is exactly European light cycle.
Manual mode means that user can control which road will have green or red light. For this you can use switch no 2. So you can keep lane 1 to have green or red light as long as you want or change it to have opposite light in lane 2. Of course during the changes you have interim state of yellow and red-yellow lights.
There is switch no 3 which will put all lights in crazy light mode. This is special option for kids if they are bored with regular lights or want to have disco lights in their room.
Step 9: Summary
I hope you like this project. I had a lot of fun building this crossing. In the future I plan to add pedestrian crossing which will be triggered with micro switch. This will require interrupts implementation. Arduino Mini Pro has only 2 pins able to handle external interrupts, so 2 pedestrian crossings will be possible.
I wait for feedback from kids which will be playing with this crossing. In case there will be some remarks I'll share it with you.
If you have some questions let me know.
Keep creating and have a nice day!