Man, two boys, and lego robot with black and white dog face

How to Create a Robot: Easy RC Puppy

Haven’t you always wanted to know how to create a robot? Read on to learn how to create an easy robot that you can build at home.

We call this robot Fido, because he comes when you call him with your working cardboard remote control!

This project and all Geek Pack Hack activities must be undertaken with a suitable adult completing their own risk assessment and supervising their children at all times.

Like with most of our projects, kids of all ages can have a blast making this robot and learning about electronics. There are some small parts that need to be positioned correctly and may need an adult’s help. 

Of course, the smallest children must be closely supervised around any small parts.

Before getting started, if you want a crash course in electricity basics, check out our post on electrical current, resistance, and voltage.

If you aren’t already familiar with breadboards, you might want to check out this post on how to use a breadboard.

We’ll list the parts we used and then give you step-by-step instructions for how to create a robot using an infra-red remote-control circuit.

You can check out our video tutorial here and subscribe to our YouTube channel to keep up with new projects.

Everything is explained below as well (but you have to watch to see why Dad has a different name for this robot…)

Infrared Light

Infrared light is an electromagnetic wave like visible light, but it has a slightly longer wavelength, and so we can’t see it with our eyes.

Relative lengths of radio waves, infrared light, the visible spectrum, uv radiation and X-ray radiation shown (not to scale).

Because infrared is so close to the wavelength of red light, many digital cameras can detect infrared light. If you point a remote control toward a digital camera, there’s a good chance that you’ll see a little red dot on the camera’s screen. 

You won’t see anything, though, just looking at the infrared bulb on the remote control with your eyes.

Interestingly, even though people can’t see infrared light, some animals can.

We built an infrared remote control circuit to get Fido to come when we want him.

Robot Transmitter Circuit

The remote control transmitter is just an infrared LED light connected to a battery.

Since you have to be careful to limit the current flowing through an LED, we included a couple of resistors in the circuit like this:

Robot transmitter circuit with IR LED, battery, and 2 resistors

Robot Receiver Circuit

To allow infrared light to trigger Fido, we use an infrared phototransistor.

The infrared phototransistor outputs an electric current when infrared light hits it. The electric current output by the phototransistor is very weak, so we use a MOSFET to amplify that current. 

Then we send that current from the MOSFET to a motor, which turns Fido’s wheels. 

Infrared light induces current through the phototransistor, which is amplified by a MOSFET before driving a motor.

Of course, we have to make sure to complete the circuit for electricity to flow; more on that below.

Supplies to Create a Robot

2 Lego Technic bricks 1×16 with holes (Item # 3703)

4 large wheels for Lego Technic axles

2 Lego axle 12 (Item # 3708)

2 Lego plate 2×8 (Item # 3034)

TT motor

2 TT motor compatible cross axles

Mini breadboard

N-channel MOSFET

IR phototransistor

Battery holder for 4 aa batteries

6 aa batteries

Battery holder for 2 aa batteries

Infrared LED

2 2.7 ohm resistors

100k ohm resistor

Insulated copper wire

Wire connectors

Wire strippers

Scissors

Cardboard

Tape

Robot puppy printable

Steps to Create a Robot

Step 1: Make the transmitter

Step 2: Build the body of the robot

Step 3: Make the receiver

Step 4: Attach receiver to the robot body

Step 5: Give the robot a face

Step 1: Make the robot transmitter

Cut cardboard into a rectangle to support your transmitter circuit.

Create a circuit as shown below using the IR LED, two 2.7 ohm resistors, batteries, battery pack, and wire connectors. Tape the circuit to the cardboard.

Robot transmitter circuit including battery pack, IR LED, and two 2.7 ohm resistors wired in series.

Step 2: Build the body of the robot

Here’s what the bottom of the robot body looks like:

Image of bottom of robot body showing four wheels attached to axles through rails, two flat plate pieces on the front of the rails and the motor attached to axles at the back.

Put the cross axels on both sides of the motor and, as shown above, stick them through the holes on the rails before attaching the tires.

Insert the long axles through the rails as shown in the image above, and attach the remaining tires.

Attach the 2 flat plate pieces as shown.

Use a rubber band to attach the round end of the motor to the adjacent long axle.

Here’s a picture of the top of the robot body:

Image of top of robot body showing four wheels attached to axles through rails, two flat plate pieces on the front of the rails and the motor attached to axles at the back.

Step 3: Make the robot receiver

Here’s how to wire up the receiver on a mini breadboard:

Mini breadboard with a circuit including an optical sensor with a phototransistor, a 100k-ohm resistor, an n-channel MOSFET, a couple of jumper wires and insulated wires attaching to the motor and battery pack.

The above image is quite large; you can expand it in a separate window.

Make sure the dark half of the optical sensor (the phototransistor) is on the left, as shown in the photo.

That’s a 100k-ohm resistor. As indicated by the text, the black and red wires on the left attach to the motor, and the red and black wires on the right attach to the battery pack.

Step 4: Attach receiver to the robot body

Peel off the mini breadboard backing and affix the breadboard to the battery pack.

Then, use masking tape to affix the battery pack to the robot body like this:

Step 5: Give the robot a face

Print and cut out the puppy face printable above or design your own robot face! Make sure to cut a little hole for the phototransistor to poke through and to attach the face. Here’s what our robot looked like (the phototransistor pokes through his nose):

Time to take your new robot puppy for a spin! Simply point the transmitter toward the face of your robot, and it will come to you!

If you enjoyed this project or have questions, please let us know. For more beginner robot projects, you might also enjoy:

Are there other projects you’d like us to build? Please leave us a comment!

Check out all of our cool engineering projects.

Or, narrow in on our simplest basic electrical circuit projects or our slightly more advanced electrical engineering projects. 

We also have a helpful basic electronics page that teaches skills such as how to use a breadboard and multimeter.

Don’t forget to sign up for our free monthly newsletter to receive Geek Pack Hack updates along with an even wackier simple circuit project. Have fun!

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