Assessment Card

• Name the scientists that contributed in the history of electronics and their contributions. 

• List the different types of Logic Gates. 

• Distinguish Capacitors, Inductors, and Transistors. 

• What is a lattice? 

• What are the ways to test a transistor?
• 
  

•          What are the types of transistor? What is commonly used transistor? 

ASSESSMENT CARD :)

Create a logic circuit that will light a seat belt warning lamp if a cars engine is on and the drivers seat belt is not plugged in. Draw your circuit, labeling its inputs and output. Verify your circuits operation using a truth table.





Create a logic circuit that will sound an alarm when an industrial freezers temperature is not below 0˚C or the freezer door has been left open. Draw your circuit, la-beling its inputs and output. Verify your circuits operation using a truth table


Create a logic circuit that activates a greenhouse fan when the greenhouse tem-perature is over 30˚C and its daylight, or whenever the ventilation shutters have been opened. Draw your circuit, labeling its inputs and output. Verify your circuits operation using a truth table

Optoelectronic Components

Compounds formed by the elements from group III of the periodic table such as aluminum, gallium, and indium, and from group V such as phosphorus, arsenic and antimony are of special interest. These elements are used to make semiconductor devices that emit light efficiently such as LED’s or that exceptionally high frequencies.
Photodiode is used in digital communication. Electrical pulses are used to turn the diode on and off.

Programmable Controllers
Programmable - Appliances that can be given instructions to operate at devices automatically at certain times of a day.
More sophisticated controllers can take into account several different factors as they respond to sensors in the system. Modern automatic washing machines are controlled by a microprocessors.

CONDITIONS WHICH DETERMINE THE STEPS AND THEIR SCHEMATIC CIRCUITS ARE:

1. the water valve can be opened by the controller only if the water level is below a present level, detected by the water sensor.

2. The heater will operate only if hot wash cycle has been set, and will switch off once the temperature sensor signals that the required temperature has been reached.

3. The motor will not operate until the water is at the right level and the required temperature has been reached.

4. The door will not open when the water is in the machine.

INTEGRATED CIRCUITS and LOGIC GATES

The Integrated Circuit

Integrated circuits placed all components in one chip, drastically reducing the size of the circuit and its components.

In 1958 and 1959, Jack Kilby at Texas Instruments and Robert Noyce at Fairchild Camera, came up with a solution to the problem of large numbers of components, and the integrated circuit was developed. Instead of making transistors one-by-one, several transistors could be made at the same time, on the same piece of semiconductor. Not only transistors, but other electric components such as resistors, capacitors and diodes could be made by the same process with the same materials.
For more than 30 years, since the 1960's, the number of transistors per unit area has been doubling every 1.5 years. This fantastic progression of circuit fabrication is known as Moore's law, after Gordon Moore, one of the early integrated circuit pioneers and founders of Intel Corporation. The Nobel Prize in Physics 2000 was awarded to Jack Kilby for the invention of the integrated circuit.
From the dawn of the vacuum tube triode, to the discovery of the transistor and the development of the integrated circuit, the 20th century has certainly been the century of electronics.



http://www.pbs.org/transistor/background1/events/icinv.html
http://nobelprize.org/educational/physics/integrated_circuit/history/index.html


Videos:

http://www.youtube.com/watch?v=uSRIc-sEgPw
 http://www.youtube.com/watch?v=ZVhVGItnea8


LOGIC GATES 

Boolean functions may be practically implemented by using electronic gates. The following points are important to understand.

• Electronic gates require a power supply.
• Gate INPUTS are driven by voltages having two nominal values, e.g. 0V and 5V representing logic 0 and logic 1 respectively.
• The OUTPUT of a gate provides two nominal values of voltage only, e.g. 0V and 5V representing logic 0 and logic 1 respectively. In general, there is only one output to a logic gate except in some special cases.
• There is always a time delay between an input being applied and the output responding.

Truth tables are used to help show the function of a logic gate. If you are unsure about truth tables and need guidence on how go about drawning them for individual gates or logic circuits then use the truth table section link.

http://www.ee.surrey.ac.uk/Projects/Labview/gatesfunc/TruthFrameSet.htm

Logic gates

Digital systems are said to be constructed by using logic gates. These gates are the AND, OR, NOT, NAND, NOR, EXOR and EXNOR gates. The basic operations are described below with the aid of truth tables.

AND gate

The AND gate is an electronic circuit that gives a high output (1) only if all its inputs are high.  A dot (.) is used to show the AND operation i.e. A.B.  Bear in mind that this dot is sometimes omitted i.e. AB

 

OR gate

The OR gate is an electronic circuit that gives a high output (1) if one or more of its inputs are high.  A plus (+) is used to show the OR operation.

 

NOT gate

The NOT gate is an electronic circuit that produces an inverted version of the input at its output.  It is also known as an inverter.  If the input variable is A, the inverted output is known as NOT A.  This is also shown as A', or A with a bar over the top, as shown at the outputs. The diagrams below show two ways that the NAND logic gate can be configured to produce a NOT gate. It can also be done using NOR logic gates in the same way.

 

NAND gate

This is a NOT-AND gate which is equal to an AND gate followed by a NOT gate.  The outputs of all NAND gates are high if any of the inputs are low. The symbol is an AND gate with a small circle on the output. The small circle represents inversion.

 

NOR gate

This is a NOT-OR gate which is equal to an OR gate followed by a NOT gate.  The outputs of all NOR gates are low if any of the inputs are high.

The symbol is an OR gate with a small circle on the output. The small circle represents inversion.

 

 

EXOR gate

The 'Exclusive-OR' gate is a circuit which will give a high output if either, but not both, of its two inputs are high.  An encircled plus sign () is used to show the EOR operation.

EXNOR gate

The 'Exclusive-NOR' gate circuit does the opposite to the EOR gate. It will give a low output if either, but not both, of its two inputs are high. The symbol is an EXOR gate with a small circle on the output. The small circle represents inversion.

The NAND and NOR gates are called universal functions since with either one the AND and OR functions and NOT can be generated.
Note:
A function in sum of products form can be implemented using NAND gates by replacing all AND and OR gates by NAND gates.

A function in product of sums form can be implemented using NOR gates by replacing all AND and OR gates by NOR gates.

Table 1: Logic gate symbols

Table 2 is a summary truth table of the input/output combinations for the NOT gate together with all possible input/output combinations for the other gate functions. Also note that a truth table with 'n' inputs has 2ⁿ rows. You can compare the outputs of different gates.
Table 2: Logic gates representation using the Truth table

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Example

A NAND gate can be used as a NOT gate using either of the following wiring configurations.

                                        (You can check this out using a truth table.)

TRANSISTORS :)

A transistor is a semiconductor device used to amplify and switch electronic signals. It is made of a solid piece of semiconductor material, with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current flowing through another pair of terminals. Because the controlled (output) power can be much more than the controlling (input) power, the transistor provides amplification of a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.
The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Following its release in the early 1950s the transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things.


Read more:

http://www.kpsec.freeuk.com/components/tran.htm

http://www.kpsec.freeuk.com/trancirc.htm 

http://nobelprize.org/educational/physics/transistor/history/ 
hhttp://en.wikipedia.org/wiki/Transistor

Solid State Diode

SOLID STATE DIODE

Combining two or more layers of p-type and n-type material results in various devices. Two of the more common ones are solid-state diode.

 http://en.wikipedia.org/wiki/Diode

http://www.kpsec.freeuk.com/components/diode.htm 

http://www.allaboutcircuits.com/vol_3/chpt_3/1.html






 

Capacitors and Inductors

CAPACITORS

The capacitor is another important component of an electronic circuit. it stores electric charges. The simplest capacitor is made of two metal plates with a small gap between them. The small gap can just be air or any insulating material such as ceramic, mica, paper,paper, plastic, or electrolyte
.

 For more details:

 http://www.youtube.com/watch?v=zNpbdptwxlQ

http://www.youtube.com/watch?v=HRwgjwNdMWU&feature=related


      The capacity of the parallel plates to store charge or the electric capacitance of a pair of parallel plates depends on its dimensions. For a capacitor of fixed value, two equal parallel plates have a capacitance given by


                                       C = εA/ D

 where

               C = capacitance in farad (F)
               A = surface area of one plate (m²⁾
                    d= separation between plates (m) and
               ε = permittivity of the space between the plates

Above the formula shows that the closer the plates are to each other, the bigger their capacitance.  A bigger plate area A results in higher capacitance. Insulators inserted between the plates, which are called dielectrics, also affects the capacitance since they are of varying values of primitives.

INDUCTORS

    Any inductor is an electromagnet. Whereas a capacitor stores energy in the electric field in the space between the plates, an inductor stores energy in the magnetic field around its coil.


For more details:

http://www.youtube.com/watch?v=hov7mTQ8MUM
http://www.youtube.com/watch?v=TQ_ETfiyZU8
http://www.youtube.com/watch?v=NIr66Y_ciiA



Capacitors and Inductors are used in oscillator and tunning circuits of radio communication systems. On the transmission side, the oscillator circuit generates the radio frequencies which modulate the audio signals.