A breadboard is a reusable plastic board with holes that allows you to build and test electronic circuits without soldering.

Breadboard

Prototyping

The ESP32-C3 Beetle is a coin-sized development board that you can use as a bridge between the digital world (Wi-Fi/Bluetooth) and the physical world (motors, lights, buttons).

ESP32-C3 Beetle Development Board

Microcontrollers

Jumper wires are small, flexible wires used to make temporary electrical connections between components, usually on a breadboard or between modules in a circuit.

Jumper Wire

An **LED (Light Emitting Diode)** is a special type of diode that lights up when electricity flows through it in the correct direction.

A diode is an electronic component that lets current flow in only one direction (Anode/Positive to Cathod/negative):

- **Anode (+)**: The positive side.
- **Cathode (-)**: The negative side.

When the anode is connected to a higher voltage than the cathode, the diode allows current to pass through.

If the voltage is reversed, the diode blocks the current.

### Polarity

An LED has two pins. The longer pin is the positive side (+), and the shorter pin is the negative side (-). It only works if the positive pin is connected to a positive voltage and the negative pin to ground or zero volts.

### Voltage Requirements

LEDs need a certain voltage to turn on. If the voltage is too low, the LED won't light up. If it's too high (more than about 3.3V), the LED might get damaged.

### Current limit

LEDs also have a limit on how much current they can handle. Exceeding this can damage them. For example:

- **Red LEDs:** 1.9-2.2V, max 20mA, recommended 10mA.
- **Green and Blue LEDs:** 2.9-3.4V, max 10mA, recommended 5mA.

Different coloured LEDs have different voltages, because the voltage needed to light up an LED depends on the material it is made from.

Each LED colour comes from a material with a certain **band gap**. The band gap is the energy needed to release light when electricity passes through.

For example, blue light has a shorter wavelength than red light, which means it needs more energy to produce.

(the colour of the LED is created at an atomic level inside the LED, not by the colour of it's cover).

### Resistor Needed

You **cannot** connect and LED straight to a power supply. You must use a resistor to limit the current and protect the LED from burning out.

## How to use an LED

To use an LED safely and correctly in a circuit:

1. Identify which pin is which: Anode (+) and Cathode (-).
2. Match the voltage: Red LEDs require 1.9-2.2V and Green/Blue require 2.9-3.4V.
3. Use a resistor to limit the current and protect the LED from burning out. Use Ohm's Law to calculate the resistor value (check out the resistor page for how to do this).
4. Connect the LED in the right direction: Connect the anode to the positive side of the power supply through the resistor. Connect the cathode to ground (0V).

A simple circuit will look like this:

Power (+) → Resistor → LED Anode → LED Cathode → Power (-)

5. Turn on the power once the LED is connected correctly with a resistor. The LED should light up.

An LED is a small light that come in a few different colours like red, green, blue or white. They don't use much power or get very hot.

LED (Light-Emitting Diode)

Actuators

## What is a resistor?

A **resistor** is a small component used in electrical circuits to limit or control the flow of electric current. It doesn't store energy, it just resists current.

### Unit of measurement Ohms (Ω)

Resistance is measured in **ohms**, written with the symbol **Ω**.

Sometimes you'll see:
- **kΩ** for kilo-ohms = 1,000 ohms.
**MΩ** for mega-ohms = 1,000,000 ohms.

## Why use a resistor?

- To protect components like LEDs from too much current. It'll slow down the flow of current so only a safe amount reaches the LED.
- To control how much current flows through a part of a circuit, because different parts may need different amounts of current.
- To divide voltage in a circuit. If you connect two resistors in series and measure the voltage between them, you'll get a fraction of the total supply voltage.
- To set timing in circuits. Resistors are often used with capacitors to create delays or timing functions (how long something stays on or how fast it blinks).

## How a resistor works

Resistors work by resisting the flow of current. How much they resist depends on their resistance value (in ohms).

This relationship is described as **Ohm's Law:**

![ohms_law.png](https://zqlevjinwifjmnhpkcsf.supabase.co/storage/v1/object/public/component-images/58dd23de-6ff4-4b10-9694-bf786ee88a99.png)

Where:
- **I** = Current in amperes (A)
- **V** = Voltage in volts (V)
- **R** = Resistance in ohms (Ω).

What this means:
- If **voltage stays the same**, and you **increase resistance**, the current goes down.
- If you **decrease resistance**, more current flows.
- If you know any two values (voltage, current or resistance, you can calculate the third).

Example:

Let's say you have a 5V power supply and connect it to a 1,000 Ω (1kΩ) resistor:

![ohms_law_example.png](https://zqlevjinwifjmnhpkcsf.supabase.co/storage/v1/object/public/component-images/20342dc8-c568-4a80-9070-721ab2c572e6.png)

This means **5 milliamps** of current will flow through the resistor. 

If you use a **2,000 Ω** resistor instead:

![ohms_law_2000.png](https://zqlevjinwifjmnhpkcsf.supabase.co/storage/v1/object/public/component-images/1a5d3b49-93f6-4188-af55-f3a26afed4d2.png)

That's less current, because the resistance is higher.

I made this lil calculator to save you working it out yourself:

[ohms-law-calculator]

Resistors are used to limit current, divide voltage or pull signals up or down.

Components

Breadboard

ESP32-C3 Beetle Development Board

Jumper Wire

LED (Light-Emitting Diode)

Resistor