Sola Car With Micro:bit Controller

Hi everyone,

This solar panel car was made for an assessment for school, we had a certain criteria that we had to follow. Making sure that the car would work on multiple different surfaces and include such things as a breadboard, capacitor, etc.

For this solar panel car you will be needing:

• A 5V solar panel
• A micro:bit
• Driver expansion
• Solar power manager
• Capacitor
• Alligator clips
• Laser cutter
• 3D printer
• Resistor pack
• Breadboard
• Mat Board
• Bike Tyre/some type of rubber that can fit around the wheels
• Motor
• Cardboard plastic
• Axis
• Zip ties

I used onshape to create this design. I drew up with CAM software, then used CAD software then had laser cutted the file. If you do not have access to a laser cutter, you are able to use cardboard as an alternative which can be hand cut to desired shape. If not happy with the chassis or would like to make your own I have linked a tutorial on how to use onshape.

I then created the designs of the back wheels, motor holder and servo mount on onshape. You will then need to 3D print these designs using acrylic. I have uploaded the designs. There are also two different types of back wheels that you can use, you will also need to print two copies of the same wheel.

Alternatives:

For the wheels you can use some type of plastic or even plastic bottles/lids.

For the motor holder you can secure the motor to the chassis with zip ties, same thing for the servo mount.

For the front steering I used plastic wheels that have been already made but feel free to create your own wheels. I connected the wheel on the axis, make sure to cut a bit of cardboard plastic to fit the axis through, then add stoppers before attaching the wheels on either side so the cardboard plastic won't move up and down.

Screw on the servo holder to the front of the chassis to make sure it does not move, this can also be done with glue. The front of the chassis is the sharper point at one of the ends, make sure to screw it right at the top. Place the servo into the holder. Using the wheels that are attached to the axis, attach it onto the servo by adding a clip that can fit onto the servo.

Using the wheels that you have 3D printed or created, you want to attach a rubber tyre (or some type of rubber) to the outside of the wheels.

To do this, you wheel need to measure out how much of the rubber needs to be cut to fit the length and the width of the wheel. I used a sharpie to sketch out where I was going to cut. After cutting the correct size of rubber you will need to hot glue it around the outside of the wheel. For this process it may take a little while as you need to wait for it to dry to continue doing it all around the wheel. Do these steps for both back wheels.

To connect the motor to the wheels, slip in the motor into the holder that you created. Attach this to the back of chassis, in the middle, using zip ties. Then you can slip on the wheels to the axis' of the motor. If the wheels are falling off easily, you may need to screw them on.

You will now need to code the micro:bit so we can manage the energy from our power source. I have provided the code for this. You will need to connect your micro:bit to your laptop and download the code onto the micro:bit by dropping the file in it.

There is a lot of steps involved in this but I have inserted diagrams that will hopefully help more with this.

Step 1:

Firstly, you are going to want to connect the wires of your solar panel to the solar power manager, making sure that positives and negatives line up. You then want to connect the capacitor to the shorter side of the solar power manager. This is bringing power from the solar panel to the capacitor which stores all the energy.

Step 2:

Next using wires, you want to attach the expansion board to the capacitor making sure that positive is aligned with positive and negative aligned with negative. MAKE SURE POSITIVE AND NEGATIVE DO NOT TOUCH EACH OTHER, this could create the circuit to not work! The capacitor charges the expansion board.

Step 3:

Add the coded micro:bit into the expansion board making sure the a/b controls are facing the front. The micro:bit is coded to turn the motor off and on, as well as measuring voltage.

Step 4:

Next using a breadboard, attach three resistors to the board, at the front of the bread add a 330 resistor, to one of the sides then add a 47.0 and a 42.52 resistor making sure they do not touch. We use 330 and 86 (47.0 + 42.52) resistors because it helps divide the voltage.

Step 5:

Using alligator clips attach one of them to the gnd hole at the bottom of the micro:bit attaching it to the 330 resistor, attach another alligator clip to the Opin hole of the micro:bit and to the other side of the 330 resistor. The code on the micro:bit measures the voltage. Using one more alligator clip, attach it to the 47.0 resistor and then to the solar power manager.

Step 6:

Finally, wire the motor to the expansion board, making sure once again that the positives and negatives alline.

There you have it, that's all the wiring for the solar panel car.

Place all wiring on the chassis, making sure wires do not cross over and keeping it neat! You may need to use zip ties and blu tack to stick the components on.

Now since you have a chassis with all the components attached on top, you now need to position the solar panel onto the car making sure that enough sun will be able to reach it. You can do multiple things with this but I positioned the solar panel so that it was tilted onto the wiring in an upright layout using zip ties to attach it to the chassis.

There you have it, a solar panel car that you built from scratch!