1. Engineering Lecture1: Logic Circuits & Concepts about basic Electrical Engineering Devices
by Christin Sander

2. Overview Logic Circuits Electrical Engineering Analogue vs Digital
Binary Numbers
Logic Gates
Boolean Algebra
Flip-Flops & Clocks
Counters
Data Storage
Electrical Engineering
Overview of Transistors
Amplifiers
Operational Amplifiers

3. Analogue versus Digital
ANALOGUE signals vary in a continuous way, can take any values
DIGITAL signals represent information as a sequence of discrete varying physical quantities, encode values into binary numbers (0 or 1)

4. Analogue to Digital Conversion
In nature, signals normally occur in an analogue way
To convert them into a digital signal, a threshold value is selected.
For values below the threshold: 0
For values above the threshold: 1

5. Binary Numbers Binary Number System
Decimal Number System
The decimal number system is the base 10 number system
Uses 10 different symbols (0,1,2,…..9)
In General, any number system can be used
Binary Number System
The binary number system is the base 2 number system
Uses 2 different symbols (0 and 1)
A BInary digiT("BIT") in each position
Binary logic circuits are useful for making controllers
A binary system can also represent numbers of any magnitude
Logic circuits can be realised which will perform arithmetical operations on these binary numbers
This is the principle behind almost all digital calculators and computers

6. Logic Gates
Electronic circuits with one or more input wires and one output wire
The voltage on the output depends on the voltages on the inputs
The relationship between inputs and output is a logical function, determined by the circuit arrangement inside the gate.
Circuit
(made up of transistors used as switches)

7. Logical Functions

8. Boolean Algebra

9. Flip-flops
Divide-by-2-circuit
D Flip-flop
Ripple-Down Counter

10. J-K Flip-flop Q+ indicates the value of Q after the next clock pulse
If J and K are different, Q takes on the value of J
If J and K are both 0, Q remains unchanged
If J and K are both 1, Q changes to its inverse (it "toggles")
Information from J and K is read in on the rising edge of the clock, and is translated into action at the Q outputs on the FALLING edge of the clock

11. Synchronous Counter
Synchronous Counter (8-bits)

12. Data Register
A circuit which can store temporarily all bits of a binary number
A 3-bit register
(a typical personal computer will have several 16-bit and 32-bit data registers in its arithmetic unit)

13. Storage Devices: ROM
A ROM cell
Typical m-ROM device

14. Transistors Small input current controls a large output current
Can act as a switch if in saturation or cut-off region

15. Amplifiers
An amplifier is a device that accepts a small signal and outputs a larger signal that generally matches the waveform characteristics of the input It amplifies the input signal
Factors affecting amplification
Gain: Relationship of input and output signal
Efficiency
Bandwidth
Settling time
Noise

16. Operational Amplifiers
An opamp is a device that takes an analogue signal and amplifies it
Output voltage depends on difference of input voltage
Applications:
Analogue to digital converters
Filters
Comparators