What is a Circuit?

A circuit is a path for electricity to flow through various electronic components. Circuits are in pieces of technology all around us, from the computers on our desks to the stop lights in our streets.

How do circuits work?

A direct current (DC) circuit consists of a current source, like a battery, and one or more “loads”. Loads are components that use electricity, like lights, motors, and resistors. Each load takes in electrical energy, and converts it to some other form of energy. For instance, a light bulb transforms electrical energy to light and heat energy. Direct current requires a lower amount of electricity than alternating current so it tends to be the most common type used in these small circuits.

Direct current has a specific direction for electricity to flow. The path of electricity starts from the positive end of your DC source of power, like a battery, and ends in the negative side of the power source.

How to make a circuit

In order to create a DC circuit, we will use a breadboard. A breadboard is the crux of creating simple circuits, which allows hobbyists to plug in wires and loads. Breadboards contain holes for plugging in wires. The design makes it easy to create and recreate circuits.

Breadboards work by having strips of metal underneath the holes on the board.

On the underside of the breadboard, the top and bottom rows of holes connect horizontally. The remaining holes connect vertically in two columns. Each column is assigned a number from one through thirty, and the rows are grouped a – e and f – j.

In the top or bottom rows, connect a source of power, like a battery. Electricity flows across each of those rows separately. Up the plus side and back down the minus side. A circuit must make a circle from this plus to this minus.

The columns 1 through 30 are electrically connected in sets of 5 holes in each column (a through e, and f through j). Only by connecting wires across these sets of 5 holes can electricity be passed through other connections.

Attach a load to a column of the breadboard. The first connection has to start at a positive electrical column, and then can branch to one of the middle sections.

By repeating these simple steps, you can connect power to multiple columns while following the path of electricity.

A simple circuit

In order to create this circuit, we will use a DC motor, a 9V battery, and a breadboard. First, connect the battery’s red to the positive row of the breadboard. Plug in the negative end of the 9V battery to the negative end of the breadboard.

Follow the same process for the DC motor. The motor will rotate in one direction if wired correctly.

The electrical circuit that we created sends electricity from the + side of the battery, down that column to the red wire of the motor. It continues through the motor, coming out the negative side, and returns to the negative side of the battery. A closed circuit.

Try switching the wires and see what happens!

A complex circuit

Here is a more complex circuit that is used in our Arduino Robotics class at SDM. It is powered by two 9V batteries and powers two motors and a light with the flick of a switch.

Try to follow the electricity with your finger. Why are there two batteries? Do they power the same things?

Here is a diagram with the electrical flow outlined in yellow using a circuit diagramming tool. Is that what you expected?

If you would like to explore more about circuits, email or call us and we will be happy to assist you! If you have questions, or we missed something, please use our contact form to send us a message. Thank you!

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