Digital Electronics (GCSE Physics)

Digital Electronics

Analogue and Digital Signals

Analogue Signals

Analogue signals vary and can be of any value.

Digital Signals

Digital signals can only be one of two values.

Logic Gates

A logic gate is a component in an electronic circuit which produces an output. The output is dependent on the input.

There are several types of gates:

• A NOT gate has a single input and output. For a NOT gate, an input of 1 will produce an output of 0. An input of 0 will produce an output of 1.
  
• An AND gate has two inputs and one output. For an AND gate, the two inputs need to be 1 in order for an output of 1 to be produced. If only one input is 1, the output will still be 0.
  
• An OR gate has two inputs and one output. One of the two inputs need to be 1 in order for an output of 1 to be produced. If both inputs are 1, the output will still be 1.
  
• A NAND gate works opposite to an AND gate. It has two inputs and one output like an AND gate. The output it always 1 unless both of the inputs are 1.
  
• A NOR gate works opposite to an OR gate. It has two inputs and one output like an OR gate. The output is only 1 if both of the inputs are 0.
  

A truth table can be used to work out the output of a circuit, based on the different inputs. This would show the different possibilities of outcomes in a circuit.