My kids love when we make little homemade “robots” that move and wiggle around. I’ve been wanting to make something more car or rover-like with wheels for awhile, but I wasn’t exactly sure how to connect the motor to the wheels. This little propeller car kind of feels like cheating, since the spinning of the motor is not directly connected to the spinning wheels, but it still works. Most important, my kids thought it was cool.
This little car makes a great first electronics project for kids since they get to put together a simple circuit. Fortunately, it’s not very expensive, since we mostly used free, recycled parts like our deli meat container and bottle caps. Next I want to try to make something powered by solar panels from the 99 cent store instead of batteries. (Sign up for my newsletter to stay up to date.)
You can watch a video of our car in action below. Note that the way I hooked up the circuit, the fan pulled the car instead of pushed it. To get the car to move the opposite direction, you would just need to switch the leads on the motor. (Or you could make the car even more awesome by using a DPDT (double pole double throw) switch instead of the simple ON/OFF switch that we used. That would allow you to toggle the direction the car moved depending on which way you flipped the switch.)
Recommended Age Range: Kindergarten, Elementary, Middle School (younger kids will need adult supervision and assistance since this project uses hot glue)Time Required: ~30 minutes
Cost: Around $10 in used supplies (The propeller is the most expensive component. I bought 4 of the one listed below for $16 total though the price fluctuates. It was $3.10 per propeller plus around $3 shipping and handling for all 4, so there is definitely a benefit to buying in bulk. A different, less expensive propeller could be used as long as it has a 2 mm shaft hole diameter.)
- Lightweight car body (we used a deli meat container, but you could also use a block of foam)
- 4 bottle lids for wheels
- 2 straws
- 2 skewers
- 1 popsicle stick (for mounting motor, not needed if you used a block of foam or something flat)
- 2 AAA battery holder
- 2 AAA batteries
- 1.5-3 V DC Motor
- Short piece of wire (I used 22 gauge, but it’s not really important)
(If the one I used is out of stock, these should work as well.)
Supplies & Tools:
- Wire cutters
- Wire strippers
- Needle nose pliers
- Hot glue gun
- First, cut the two straws so that you can attach the wheels to the bottom of the container. The length should be a little bit more than the length of the bottom of the container plus the width of the 2 wheels as shown. If you cut the straws too short, then the wheels might hit the container, which is not a major problem.
- Hot glue the straws onto the bottom of the container.
- Cut the skewers so that that they are slightly longer than the straws.
- Hot glue a “wheel” onto one end of each skewer.
- Thread the wheel plus skewer through the straws.
- Hot glue the other wheel onto each skewer.
- If needed, glue a popsicle stick or something flat onto the lid of the container to create a flat surface on which to mount the motor.
- Next attach a lead from the battery pack to the switch. Ideally, the lead would be soldered to make a more permanent connection, but since I don’t want my kids around soldering irons at the moment, we just used needle-nosed pliers to wrap the wire around the post on the switch.
- Attach the other lead from the battery pack to the motor.
- Next, you need to make a little jumper wire to connect the switch to the motor and complete the circuit. Cut a piece of wire from your spool and strip off the ends using the wire strippers as shown. Depending on what type of wire strippers you have, you might need to adjust the screw on your wire strippers so that when they are closed, the hole is about the size of the internal wire.
- Connect the short wire to the motor and switch making a triangle with your 3 components (battery, switch, motor).
- Next push the propeller onto the motor shaft. Mine press fit snugly together, but if not, you can add a little hot glue. Just make sure not to get glue near where the shaft connect to the motor.
- Glue the motor onto the top of the car, making sure not to cover any vents on the motor. You can also glue the switch and battery pack down, but it’s not really necessary.
Now all you have to do is insert batteries if you haven’t already and flip the switch to start the car. Note that if you used a toggle switch, you’ll be able to get the car to move forwards and backwards. If you didn’t use a toggle switch, which direction the car moves will depend on what direction the motor is spinning. My car moves toward the propeller. If I wanted it to move in the other direction instead, I would just need to switch the battery pack leads. However, I’m lazy and my kids didn’t seem to mind, so we left it as is.
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