Simple Circuits with ShaKey

Difficulty
Easy
Steps
10

Circuits make computers, cameras, video games, and your favourite devices possible. Without circuits, there would be none of those! 

In this guide, you will use the ShaKey and some play-doh to create a few simple circuits with the Scratch programming language. 

Complete this guide to get familiar with circuits and build a simple door bell and security alarm.

Parts Used in This Guide

ShaKey Standard Kit
LB-SHAKEY-STD

Buy

Step 1  What is a circuit?

Circuits make computers, cameras, video games, and your favourite devices possible. Without circuits, there would be none of those! 

So, what's a circuit? A circuit is a complete, unbroken path around which electricity can flow. It must include a source of electricity, such as a battery. Here, we'll use the ShaKey board connected to your computer. 

Materials that allow electric current to flow through easily, are called conductors. In this guide, we'll use alligator clips for this. But what's electric current? In order to understand what current is, it helps to first understand atoms. Atoms are small particles that make up all matter, from your ShaKey board, to your hands, to the trees outside your window. Inside the atom are smaller objects called electrons. 

Current is the movement of these small, charged particles called electrons. Another thing that is absolutely necessary for current to flow, is voltage. Voltage is the difference in charge between two points. A common way to think of it is using the Water Tank Analogy. 

  • Charge can be thought of as the water in the pipe. 
  • Current is like the flow of water in the pipe. 
  • Voltage also known as the potential difference, can be thought of as the pressure of the water.

With all the theory aside, let's create a simple doorbell circuit using some play-doh and alligator clips with the ShaKey. Then we'll create one for a security alarm. Without further ado, let's get started!

Step 2  Create the play-doh blocks

Roll up and make two play-doh blocks of different colours. 

Step 3  Connect yellow alligator clip to yellow block

Connect one end of a yellow alligator clip to the yellow play-doh block.

Step 4  Connect black alligator clip to green block

Connect one end of a black alligator clip to the green play-doh button.

Step 5  Connect yellow alligator clip to Up

Connect one end of a yellow alligator clip to 'Up' on the ShaKey.

Step 6  Connect black alligator clip to Earth

Connect the black alligator clip to Earth. The complete set-up should look like the second picture.

Step 7  Select 'doorbell' sound

  • Now connect your ShaKey to the computer via microUSB cable.
  • Open up the Scratch editor
  • Click on 'Sounds' tab
  • Click on 'Choose a Sound'
  • Type 'doorbell' in the search box
  • Select 'Doorbell'

Step 8  Scratch code for door bell

  • Add the following blocks: "when up arrow key pressed" and "play sound ... until done". 
  • Select 'Doorbell' as the sound.
  • Now try pressing the yellow play-doh button. You should hear the door bell sounding! What happens is:
    •  The circuit becomes closed,  so current flows through the circuit 
    • The 'Up' keystroke is registered 
    • So the doorbell sound plays as programmed in our super simple Scratch program.

Step 9  Join the two play-doh blocks together

Next, connect the two play-doh blocks so that they are touching. This will complete the circuit for our security alarm!

Step 10  Scratch code for security alarm

With your ShaKey connected to the computer, delete the previous blocks and add these Scratch blocks.

Now when the space bar is pressed, it will check to see if 'key up arrow' is pressed. With the play-doh blocks joined together, we have a complete, closed circuit where current can flow. This means the up arrow input is being pressed. 

When the play-doh blocks are pushed apart, the circuit is no longer complete which will trigger the security alarm sound!