Step 1: The breadboard This is the “breadboard” – the electronics prototyping board on which we will build the circuit. The breadboard has 30 numbered rows and 10 columns labelled with the letters from A-J. Each hole in the main panel of the breadboard therefore has a unique alphanumeric code. For example, the top left hole is A1 and the bottom right hole is J30. Each short row of five holes forms a single electrical node – when wires (or pins, component legs, etc) are inserted into two holes in the same row of five, they become electrically connected. Two long continuously connected “rails” are provided on each side of the breadboard. These are normally used to distribute a supply voltage to different points in the circuit. We will be connecting the battery voltage to the red and blue rails on the left side of the breadboard, which will supply 3V and 0V respectively to the circuit.