electronics Flashcards
what does a system contain
an input process and output
example of how a bicycle works using input process and output
input - turning of the cyclists legs
process - chain and sprockets
output - rear wheel which propels e bike forward
what are circuits made of
components which are joined together by wires
what are PCB’s
- printed circuit boards
- boards with thin copper tracks (instead of wires) connecting components in a circuit
why are PCBS used
to reduce the size and the manufacturing cost of electronic systems
what is a conductor
a material that allows electricity to flow through it
why is copper used for wire tracks
because it is ductile, malleable and a good conductor
what does voltage do
pushes current around a circuit
what do resistors do
they reduce the current in a circuit so that you don’t damage delicate components
what do input devices do
they receive an external signal which triggers a system to worn
what do switches do
they turn a circuit on and off
- closed switch allows current to flow through a circuit
examples of switches
- toggle switch- flick to one position to complete the circuit
- push switch - push down and hold to complete or break the circuit
- slide switch - slide to one side to complete the circuit
what do variable resistors do
they change the resistance of a circuit based on an external factor
what are thermistors
- resistors that detect changes in temperature
- in hot conditions, t
resistance falls, in cold, it increases - used in central heating systems which turn off when a room reaches a certain temperature
what are LDRs and their uses
- light sensors, detect changes in light levels
- in brighter light, resistance falls
- used in automatic night lights
what are pressure sensors and their used
- detect changes in pressure in a system
- depending on the type of pressure sensor, resistance can either increase or decrease as pressure increases
- often used in equipment where gases or liquids are monitored. in cars, they are used to detect if there’s a leak in the fuel system. a leak would cause pressure to fall and this would trigger a warning light to come on
what do process devices do
receive inputs and determine the output
what are IC’s and what do they do and their advantages
- Integrated circuits are tiny, self contained circuits with billions of components built in
- they help simplify electronic systems by reducing the number of separate components needed in a circuit
- meaning they are cheaper and smaller, also use much less power because of their size
what is a microcontroller
- a mini computer on a chip which has a processor, memory and one or more inputs and outputs
advantages of microcontrollers
- can do the job of multiple IC’s
- unlike other IC’s, most can be reprogrammed for a different use
disadvantages of microcontrollers
more expensive than IC’s
where is the program stored in a microcontroller
in the microcontrollers onboard memory
examples of microcontroller boards
Arduino boards and BBC micro:bit
ways to programme a microcontroller
- writing a series of commands using a programming language such as BASIC and scratch
- creating a flowchart telling the microcontroller exactly when to start, how to make decisions based on input signals, when to add a time delay to the process, what to output and when to stop operating
how is programming done
using specialist computer software such as PICAXE and Logicator
what are timers used for
to add a time delay to a process and make sure parts of a program are running when they’re supposed to
- they can generate a pulse after a particular length of time has passed
how do counters differ from timers
they count pulses of voltage produced by an input device
how are microcontrollers used as timers
- microcontrollers controlling flashing lights like car indicators, use timers to set the time that the light is on and off for
- microcontrollers in microwaves use a timer to set the length of time that the oven cooks for
how are microcontrollers used as counters
- most modern cars have a dial on the dashboard that shows how fast the engine is turning ( the number of revolutions per minute)
- a microcontroller is used to count the number of revolutions
what do logic gates do
- they make decisions in ICs based on a collection of inputs
what are the types of logic gates
OR gates
AND gates
NOT gates
describe how OR gates work
- OR gates have 2 inputs. if one input or the other is on, then the output is on
- For example, an automatic door will open if a sensor detects someone on the outside or inside
how do AND gates work
- They have two inputs: both inputs need to be on for the output to be on.
- for example a tumble dryer is won’t start until both the start button is pressed and an input sensor has detected that the door is closed
how does an NOT gate work
They have one input: if the input is on the output is not on. It reverses the input
Pressing an emergency stop switch will stop the output on an escalator but it would cause it to stop moving
examples of output devices
LEDs, lamps and bulbs - turn electricity into light
Buzzers - make a noise
Speakers - turn electrical signals into sound
