Elec 4 AQA

A summary of some of the things that you need to know for AQA Elec 4 , Electronics.

HideShow resource information
  • Created by: Joey
  • Created on: 23-05-13 19:36
View mindmap
  • Elec 4 AQA
    • Feedback
      • Closed Loop
        • Negative - Feedback reduces effect of input and ouput reaches steady point
        • Postivie - Feedback increases effect of input
      • Open Loop - No feedback
    • Tristate Buffer
      • Has three states, logic 1,0 and open circuit
      • When OE (bar) is 0 it is connected
      • Enables Data to be transferred when needed
      • One Tristate buffer per bit
    • DAC
      • D0 - At bottom and is most significant with highest resistance
    • Schmitt Triggers
      • Two Distinct Switching Levels which can clean noisy signals and reduce multiple switching
      • Upper Switching Level when Output is High
      • Lower Switching Level when Output is Low
    • PC Vs ANN
      • Processors
        • ANN - Simple but many processors
        • PC - Very few but complex
      • Memory
        • PC - Dedicated Memory (ROM,RAM etc)
        • ANN - Stores data in weightings of connections
      • Program
        • ANN - Trained by changing values in weightings
        • PC - Follows a set of instructions hence the program
      • Tasks
        • ANN - Better at predictive tasks such as weather forecasting
        • PC - Better at calculations such as banking
    • Data Latch - Using D-Type Flip Flops
      • Obviously holds data
      • One D type flip flop per bit
      • Sends D to Q when CK pulse rises
      • For Data Latch function only Ck connections joined together
    • Conversion
      • DAC
        • D0 - At bottom and is least significant with highest resistance
      • ADC
        • Flash
          • Very Fast and Expensive
          • Number of Comparators = (2^N) -1
        • Ramp
          • Signal input is increased slowly in a ramp fashion until it is greater than the DAC output
          • Slow in comparison to Flash ADC
    • Photodiodes - Very Fast Response Compared to LED
    • Optical Shaft Encoders
      • Resolution - Minimum angle that can be turned through with change
      • Optical Shaft Encoder can be used for Direction, Speed and absolute position
      • Slotted Disk can be used for angular speed and relative position
    • Stepper Motors
      • 1.8 Degrees for 6 pole motor and 7.5 Degrees for 4 pole motor
      • Less Torque and Speed of rotation than conventional motor
      • Needs control electronics to continuously apply current to each choil
    • Illumination
      • Seven Segment Display
        • Normal calculations apply to each segment
      • Dot Matrix Display
        • Multiplexed
        • Dimmer as only on 1/5th of the time
        • LED's lit via rows and columns
        • Can display a range of characters


No comments have yet been made

Similar Electronics resources:

See all Electronics resources »See all resources »