What You Will Build
By the end of this tutorial, you will power a breadboard and turn on an LED safely using only basic components from the kit.
A breadboard lets you build circuits without soldering.
- Each row of holes is electrically connected horizontally
- The long side rails are for power (Voltage and GND; the PSU includes 3V3 and 5V)
- The center gap separates the left and right halves
If two metal legs are in the same row, electricity can flow between them.
Challenge 1: LED On/Off with Button
This project is built in Tinkercad Circuits, not on real hardware yet.
Tinkercad simulates real electronic behavior, so the habits you build here will transfer directly to a physical breadboard later.
What You Will Build
By the end of this challenge, you will have:
- A button that turns an LED on only while it is pressed
- An expanded version where one button controls multiple LEDs
You will start with a simple circuit and then extend it, not rebuild it.
Getting Started in Tinkercad
- Go to tinkercad.com and sign in
- Click Circuits → Create New Circuit
- Here, do these three tutorials! They are very useful and informative
- After finishing these, take a screenshot of the end result for each tutorial! You'll need these later.
- After that, also do these! Take a screenshot of the end result for each tutorial! You'll need these later.
- Here, do these three tutorials! They are very useful and informative
- Now, create a brand new project!
- From the components panel:
- Drag in a Breadboard — Both the Breadboard Small and Breadboard work!
- Drag in a Power Supply
- Now connect red to red and black to black. The red wire carries voltage, and the black wire is ground.
- Change the color of each!
- At the end, it should look like this:
- Drag in one LED and one resistor. Connect them as such, then wire them! Use different rows/columns than me, just to challenge yourself.
- Drag in a Breadboard — Both the Breadboard Small and Breadboard work!
You can zoom, pan, and rotate components freely. Take your time arranging things neatly; it helps you understand the connections better.
Here's what's happening here
1. Power to the power rail
You're taking the positive output of your power supply and connecting it to the red power rail on the breadboard. This rail becomes the source of voltage for the entire circuit.
2. Ground to the ground rail
You're connecting the ground (GND) of your power supply to the blue/black rail on the breadboard. This rail becomes the return path for the circuit.
3. Resistor from power rail to LED
You place a resistor between the power rail and the LED's positive leg. The resistor's job is to limit current so the LED doesn't burn out.
4. LED gets voltage
The LED's anode (long leg) connects to the resistor, which connects to the power rail. This means the LED receives voltage, the electrical "push" that makes current flow.
5. LED ground
The LED's cathode (short leg) goes to the ground rail, completing the circuit.
Electricity Basics
What "ground" actually means here
Ground is the reference point for the entire circuit. Think of it as the zero level that everything else is measured against.
- Voltage is always measured relative to ground.
- Current flows from power → through components → back to ground.
- Without ground, the circuit has no return path, so nothing works.
Ground isn't "negative energy"; it's simply the other side of the loop.
Check this for more information!
Additionally, here's some ground!
What voltage is, and why it matters
Voltage is the electrical pressure that pushes electrons through the circuit.
- Higher voltage = stronger push
- Lower voltage = weaker push
For an LED:
- Too low voltage → LED won't turn on
- Too high voltage → LED tries to pull too much current and burns out
Voltage matters because every component is designed to operate within a certain range.
Check this for more information!
What current is, and why it matters
Current is the amount of electrical flow through the circuit.
- Voltage is the push
- Current is the flow caused by that push
LEDs are current‑sensitive devices. They don't care much about voltage; they care about how much current flows through them.
Why too much current is bad
If you let too much current flow:
- The LED overheats
- The semiconductor junction gets damaged
- It permanently burns out
This is why you add a resistor; it limits current to a safe level.
HOWEVER,
The reason too much current happens is because the voltage is too high.
Voltage is the push. If the push is too strong, the LED is forced to draw more current than it can survive.
So the real chain is:
Too much voltage → too much current → LED damage
The resistor fixes this by dropping voltage and limiting current so the LED only gets what it can safely handle.
A tiny straw (LED) can only handle a small flow. If you crank up the pressure (voltage), the straw bursts. But having a huge bucket of water (a power supply capable of lots of current) is harmless. The straw only takes what it can.
How can I calculate the value I need on my resistor?
Great question!
You only need three numbers:
- Supply voltage (what your power source provides)
- LED forward voltage (how much voltage the LED "drops")
- Desired LED current (usually 10–20 mA for typical LEDs, I'll use 20mA!)
However, this is only the minimum needed! More can be added to be on the safe side, or have a dimmer LED:
Here's a table of the values you may need:
| LED Color | Typical Forward Voltage (V_LED) | Target Current |
|---|---|---|
| Red | 2.0 V | 20 mA |
| Yellow | 2.1 V | 20 mA |
| Green | 2.2 V | 20 mA |
| Blue | 3.0 V | 20 mA |
| White | 3.0 V | 20 mA |
For this example, I will be using a red LED. For your schematic, use a different color!
R = (V_supply − V_f) / I
Plug in the values:
R = (5V − 2.0V) / 20mA
R = 3V / 0.02A
R = 150Ω
So the minimum resistor value we want is 150Ω.
How resistor values are chosen
Real resistors only come in standard values. The way these values are chosen is really interesting! You should read about it here!
Your kit includes:
10Ω, 100Ω, 220Ω, 330Ω, 1KΩ, 2KΩ, 5KΩ, 10KΩ, 100KΩ, 1MΩ
We calculated 150Ω, but the kit does not include 150Ω.
So we choose the next higher safe value:
- 100Ω → too low (too much current)
- 220Ω → safe choice
Minimum (calculated): 150Ω
Value used from the kit: 220Ω
Click on the resistor and change the resistor value to the value you calculated. I used 220Ω, as shown here:
Now click "start simulation," and watch it work!
Part 1: Single LED Controlled by a Button
Goal
- The LED is off when the button is not pressed
- The LED turns on only while the button is pressed
If the LED stays on or never turns on, that simply means a connection needs adjustment.
Helpful Notes Before Wiring
- LED polarity matters — The anode connects toward the positive side; the cathode connects toward ground
- The resistor protects the LED — It must be in series with the LED; it may be placed on either side
- The button is momentary — It closes the circuit only while pressed
- A complete circuit needs ground — Current must have a path back to the negative terminal
With that in mind, just add the button!
Note: MAKE SURE THE LED IS ON THE OTHER SIDE!!! OR ELSE IT WILL JUST STAY CONNECTED TO THE VOLTAGE!!!
Note: this diagram is flipped 90 degrees!
Here, when the button is pressed, all four sides are connected!
What's Happening in the Circuit
- When the button is not pressed, the circuit is open and no current flows
- When the button is pressed, the circuit closes and current flows through the resistor and LED
- The LED lights because current is allowed to flow
You are controlling current flow, not the LED directly.
If the Circuit Does Not Behave as Expected
Try checking:
- Are the LED's two pins connected to different nodes?
- Is the resistor in series with the LED?
- Is the button actually between the power source and the LED?
- Is ground connected?
Use Start Simulation to observe changes as you adjust connections.
Here's an assembly I created IRL with my kit!
Part 3: Expanding to Multiple LEDs
Now you will build on the same circuit.
New Goal
- Pressing the button turns multiple LEDs on
- Releasing the button turns all of them off
Important Rule
Each LED must have its own resistor.
Even if Tinkercad allows one resistor to "work," using separate resistors is the correct and safe way to build the circuit. Here's a detailed explanation
Don't do this! Sharing a single resistor across multiple LEDs causes uneven current distribution. LEDs have slightly different forward voltages, so one will hog more current than the others, burn brighter, and burn out faster. In the worst case, it can damage all the LEDs in the group.
How to Expand the Circuit
- Keep the button exactly as it is
- From the button's output, create multiple parallel paths, each containing:
- One resistor
- One LED
- A return to ground
All LEDs should turn on and off together.
These are the basics of a breadboard. If you have any questions, ask in #breadboard. The actual project you build will be far more complex, with real firmware and components you choose yourself. This is just to get you started!