Power & Boards

Boards and power sources: Arduino Uno, ESP32, breadboard, battery, bench supply and ground. Each entry explains what the part does, what it looks like in CircuitBench, how to wire it and, where relevant, an Arduino code example you can paste into the code panel. New to electronics? Start with the electronics basics and the Arduino tutorial.

Arduino Uno ESP32 DevKit V1 Breadboard Battery Bench supply Ground

Arduino Uno

Boards

What it does. A beginner-friendly microcontroller board with 14 digital pins (6 with PWM), 6 analog inputs and 5 V logic.

What it looks like. A blue board with two rows of header pins and a USB connector on the left.

How to use it. Wire components to its pins, write your sketch in the code panel and press Start. Always connect GND to the circuit ground.

Code example.

void setup(){ pinMode(13, OUTPUT); }
void loop(){
  digitalWrite(13, HIGH); delay(500);
  digitalWrite(13, LOW);  delay(500);
}

Drop it on the workspace, load the “Blink an LED” example and press Start.

ESP32 DevKit V1

Boards

What it does. A faster 3.3 V board with Wi-Fi and Bluetooth, many GPIO pins and 12-bit analog inputs. Its pins tolerate only 3.3 V, so never feed them 5 V.

What it looks like. A tall dark board with pins on both long edges.

How to use it. Use it like an Arduino, but check pin numbers: they are GPIO numbers such as 2, 4 or 34.

Code example.

const int LED = 2;
void setup(){ pinMode(LED, OUTPUT); }
void loop(){ digitalWrite(LED, !digitalRead(LED)); delay(300); }

Load the “ESP32 + NeoPixels” example and see how its pins are labelled.

Breadboard

Layout

What it does. A reusable solderless board. Holes in the same column strip are connected, and the long side rails carry power and ground.

What it looks like. A pale rectangle with a grid of holes and coloured rails.

How to use it. Plug parts across the centre gap so each leg has its own strip, then wire strips to the board.

Load “Breadboard basics” to see how the strips connect.

Battery

Power

What it does. A fixed DC voltage source (0.5–24 V in the simulator). Chemical cells push current from the + terminal, through the circuit, back to −.

What it looks like. A rectangle with a red + and a black − terminal.

How to use it. Set the voltage in the inspector. Connect + to your circuit and − to ground. Higher voltage means more current through the same resistance.

Connect a battery, a 450 Ω resistor and a multimeter in Amps mode. You should read about 20 mA at 9 V.

Bench supply

Power

What it does. An adjustable lab power supply. Unlike a real battery it is ideal, so it holds its voltage steady.

What it looks like. A compact box with two terminals and a voltage label.

How to use it. Dial in 3.3 V, 5 V or 9 V to power a board or test a divider.

Set it to 3.3 V, then 9 V, and watch how an LED’s brightness changes.

Ground

Power

What it does. The 0 V reference every voltage is measured against. A circuit without a ground connection has no meaningful voltages.

What it looks like. A small symbol of three descending lines.

How to use it. Connect it to the negative side of every supply and to every board GND. All grounds are the same node.

Add a multimeter across a battery. Then remove the ground link and see what changes.

← All components · Try it in the simulator