Electronics Powered: Wheeled Robot

For this project, I designed and built an analog light-following robot using SnappyXO components.

The goal of this project was to explore the fundamentals of analog electronics by building a robot that responds to its environment without any microcontroller (like Arduino). Instead of programming, the robot relies entirely on electronic components such as transistors, photocells, and resistors to react to light and drive its motors.

By using light-dependent resistors (LDRs) and transistors, I created a simple analog control system where the robot's behavior changes based on the amount of light detected. When more light is detected on one side, the robot adjusts its movement to turn toward the light, creating a light-following behavior.

This project demonstrates how analog circuits can perform useful control functions without any digital logic or code, giving insight into how early robotics and electronics worked before microcontrollers were common.

Materials Used

Mechanical & Structural Parts

(All from the SnappyXO kit)

1. 1x 4X Plate
2. 1x 6X Beam
3. 2x 5X Beams
4. 2x Wheels
5. 2x Tires
6. 2x L Clips
7. 2x Small H Clips
8. 2x Medium H Clips
9. 2x Large H Clips
10. 2x Motor Clips
11. 2x Motor Flange Spacers
12. 8x Wheel Clips
13. 2x Motor Mounts
14. 2x Motor Supports
15. 1x 6V Battery Mount
16. 1x 6V Battery Holder
17. 1x 9V Battery Mount
18. 1x Caster Holder
19. 1x 1X Caster + Steel Ball
20. 1x Uno Board Mount (used for mounting the breadboard)
21. 4x Screws
22. 4x Nuts or Standoffs
23. 1x Screwdriver

Electronic Components

(All from the SnappyXO kit)

1. 1x Breadboard
2. 2x NPN Transistors
3. 2x Light Dependent Resistors (LDRs / Photocells)
4. 2x Diodes (For motor protection)
5. Assorted Resistors
6. 2x DC Motors
7. 1x 9V Battery
8. 1x I-Type or Barrel Jack Battery Snap
9. Jumper Wires (for breadboard connections)

Before building the electronic circuit, I started by assembling the mechanical base of the robot using parts from the SnappyXO kit. This base provided the structural support for the motors, wheels, and eventually the breadboard.

Steps for Assembling the Base:

1. Attaching the Motors
2. I used two DC motors and mounted them using the Motor Mounts, Motor Supports, and Motor Clips. These components securely held the motors on either side of the main chassis.
3. Building the Frame
4. I connected the motors using the 4X Plate and 6X Beam as the main body of the robot. The 5X Beams were used to reinforce the structure and attach other components like the caster and battery holders.
5. Mounting the Wheels
6. Each motor was fitted with a Wheel, and I added Tires to improve grip. The wheels were secured using Motor Flange Spacers and Wheel Clips to ensure they didn’t wobble during movement.
7. Adding the Caster Wheel
8. To balance the robot, I attached a Caster Holder and inserted the 1X Caster and Steel Ball under the front side of the robot. This allowed the robot to turn and pivot smoothly while driving forward or backward.
9. Battery Mounting
10. I installed the 6V and 9V Battery Holders using the battery mounts provided. This kept the power supplies secured during movement.
11. Mounting the Breadboard
12. Since I wasn’t using the Arduino, I used the Uno Board Mount as a base to secure the breadboard. This gave me a flat surface for the circuit and allowed for easy wiring and adjustments.

So this is a light-following robot circuit I built on Tinkercad, which is honestly so perfect for testing out circuits before physically building them. It’s super easy to use, and it lets you experiment without worrying about frying anything.

Basically, we’ve got a 9-volt battery powering everything, two DC motors that handle movement, and a pair of LDRs (light-dependent resistors). The LDRs sense how much light hits each side. When one side gets more light, that LDR’s resistance drops, the transistor on that side activates, and that motor spins faster. That makes the robot turn toward the light.

So in short, this setup chases light. It’s a super fun way to see how sensors and electronics can work together to create something that actually reacts to the world around it.

Once the electronics were all wired up, it was time for the real test, connecting the 9V battery and bringing the circuit to life. This is honestly the most exciting part because you finally get to see if all those components are doing their job.

After connecting the battery, both motors started responding based on how the LDRs (light sensors) were picking up ambient light. At this stage, I didn’t shine a flashlight yet, as I just wanted to confirm that the circuit was powered correctly and that nothing was overheating or wired incorrectly.

You can actually see the robot react a little even without direct light. One motor might spin slightly faster if one LDR catches more light from the room. It’s a cool moment because it shows the system’s sensitivity and how even small light changes affect motor speed.

So yeah, this step is basically that first “it’s alive” moment where the robot officially powers up and starts doing its thing before we test it with stronger light sources.

Now for the best part: the flashlight test. After confirming that everything was wired and powered correctly, I grabbed a flashlight and pointed it toward one of the robot’s photocell (LDRs) to see how it would react.

The moment the light hit, the robot started turning toward it, which means the photocell was doing exactly what it’s supposed to do. The LDR’s resistance dropped because it detected more light, which made the transistor on that side send more current to the motor. As a result, that motor spun faster, causing the robot to pivot toward the light source.

It’s honestly really satisfying to see all those tiny electronic parts connected suddenly work together like a team. You shine the light, and the robot literally chases it. It’s a small but super cool moment that shows how sensors and control systems come to life in real time.

And..............

That's all!

Building it through the SnappyXO kit made the whole process even better. It was super hands-on, easy to experiment with, and a great way to actually see how engineering concepts work in real time. I'm eager to see what else I can learn and explore!