You have 5 minutes to look over your table of sensor and outputs ready for a spot check on the different symbols Start Timer 5 mins 5 4 3 2 1

In the back of your book write the name of the symbol as it appears

Using Logic Gates 14-Sep-15 Learning Goals To be able to recognise the different input(sensor) and output symbols To understand that inputs can either be on or off and that we use 1 or 0 to denote this (binary) To recognise that we can use a logic gate to change a signal To understand what a NOT logic gate will do in a circuit

Analogue or digital?

Electronic systems are often digital devices – they often have two states on or off and a system with only two states is called ‘the binary system’

Binary Logic Electronic systems are often binary systems. A binary system has just two states: OFF and ON When it is off, the binary code is 0 When it is on, the binary code is 1 COPY AND COMPLETE Binary Code Switch Lamp Bell Current Flowing? Answer to a question Logic 1 ON YES OFF SILENT NO

Use the worksheet and the ‘Decision Module’ Board to undertake your practical and answer the questions on the worksheet

The doors on this safe are controlled by groups of push switches called logic gates. The buttons need to be pressed in the correct order otherwise the alarm will go off. This mechanism will be controlled by a circuit with logic gates.

A NOT Logic Gate NOT gates are often used in emergency-stop buttons on machine tools- they are also used on the controls to the eletricity supply in our lab. If we need to cut the power immediately we can press the red button which is a ‘push switch’ A NOT gate has just one input. It will give a high output (1) if the input is low. This is a truth table for a NOT gate. A represents the input (1 = on/high and O = off/low) Q is the output

Homework: Do Q1-6 on the worksheet ‘Electronic Systems and Logic Gates’