Inputs, Outputs, Process Components P61-65 Flashcards
Define a system
A system comprises parts or components that work together to control a task or activity
Consists of inputs, processes and outputs
Within each system there can be many subtasks or subsystems
Systems diagram
Definition
Simple versions of flowcharts that lay out the input, process, and output stages of a system
Example: automatic door
Motion sensor I Motor drives gears to open door I Delay to allow people in and out I Motor drives gears to close door
What is an open loop system
Has no feedback and is unable to make a decision
Input directly controls output
Output is unable to influence the input
Example:
Input: Switch
Process: heater on
Output: heat
What is a closed loop system
Able to make a decision using feedback
Usually from a sensor
Define input
For a system to be controlled it usually needs to be manually triggered or it needs to sense an environmental change
To do this it needs an input component or sensor - most common is a switch
Define polarity
And pole / throw
Some electronic components have a positive and negative side.
So it matters which way around they go in a circuit
Most switches do not have polarity but do have pole and throw. Electricity will only travel from pole to throw and vice versa
SPST
Single pole single throw
Simplest form of a switch
Perfect: on off switch
Can connect or break a circuit
SPDT
Single pole double throw
Has 2 options for throw
Used to control 2 outputs
Push switches
Momentary switches
Same thing
Only operate for as long as pressed
PTM
A type of push switch
Push to make
Used to trigger circuits ie door bell
PTB
Type of push switch
Push to break
Used trigger circuits is door bell
Example other input devices
3
Thermistors - heat / cold
Light dependant resistors (LDR) - detect light or dark
Pressure sensors - changes in force
