1. Sheila Porter Intel Ireland
PowerPoint Presentation III
Electronic Engineering l & ll
Sheila Porter
Intel Ireland

2. Electronic Engineering
Session 4: Electronic Engineering I
Students explore simple circuitry with bulbs, batteries, wires and breadboards
Session 5: Electronic Engineering II
Students use switches, LEDs and motors and investigate their application in the world around them
Cordless Telephone

3. Session 4: Electronic Engineering I
Key Concepts in Electricity
1. A complete circuit is needed for an electric current to flow.
2. A resistor will reduce the flow of current in a circuit.
3. The voltage of a battery or power pack is a measure of the 'push' that can make a current flow; the larger the voltage the larger the current for a given resistance.
4. Current is not used up when it flows through a circuit.
5. Not all electrical component obey Ohm's law, e.g. silicon chips, capacitors, light-emitting diodes (LEDs).
6. Circuits inside silicon chips can be turned on or off by changing the voltage they sense (rather than current).

4. Check Your Understanding
Q.1 The diagram shows a battery and lamps connected to some wires.
Why won’t the bulbs light?
What would you do to make the circuit work properly?
A.1
Circuit not complete
Link wire and bulb

5. Q.2 We measure the amount of current flowing through a circuit
in amps (A).
Suppose the circuit is made to work properly so that both bulbs light. Also suppose we measured the current flowing through the wire at P as one amp (1 A).
What would you predict the size of the current to be at point Q?
What would you predict the size of the current to be at point R?
A (i) 1 A at Q (ii) 1 A at R
Current is not used up in a circuit

6. Q. 3 Assume you had built the circuit so that both bulbs were glowing
Q.3 Assume you had built the circuit so that both bulbs were glowing. What do you think would happen if you connected a wire from P to Q?
A.3 The bulb would go out. The wire from P to Q would have a much lower resistance than the bulb, so almost all the current would go through the wire and not the bulb. The other bulb would glow more brightly.

7. Q. 4 Imagine the circuit was working properly, with both lamps glowing
Q.4 Imagine the circuit was working properly, with both lamps glowing. Now imagine you replaced the 9 V battery by a 90 V battery. Write down what you think would happen, and why it would happen.
90 V Battery
A.4 The 90 V battery would drive a much greater current through the circuit (about 10 times as much). It is likely that so much current would ‘burn out’ the filaments of the bulbs, i.e., they would glow very brightly for a brief moment and then stop working.

8. Connections on a Breadboard
Horizontal row
No connection
Vertical row
One or more horizontal rows of holes at the top. All these holes are connected together by a metal strip running underneath.
One or more horizontal rows of holes at the bottom. These holes are also connected together.
Two sets of holes in rows of five holes each, separated by a gap. These holes are connected vertically only. So, for example, two holes side-by-side are NOT connected.
There is no connection across the gap.

9. Electrical Components

10. Building Simple Circuits
Supplies
Breadboard
Battery
Electrical
wire
2 lamps
2 LEDs
Procedure 1
Build the circuit shown in the photo to make two lamps light.
Session 4, Activity A

11. LEDs – Light-Emitting Diodes
Special type of diode which gives out light when a small current flows through it (forward bias)
Flat
Lens
REMEMBER
The cathode must be connected to the – terminal of the battery

12. LEDs – Light-Emitting Diodes
6 V
330 
LEDs usually require a voltage of about 2 V to light
Anything higher and they will ‘burn out’
6 V330 
Ordinary LEDs are used with a protective resistor in series with them
The LEDs in our investigations have built-in resistors for convenience

13. LEDs – Light-Emitting Diodes
Procedure 2
Identify anode and cathode on LED
Remove bottom lamp from breadboard
Insert LED and note whether
it lights
Turn the LED around and note whether it lights
Replace both lamps with LEDs
Connected to –ve terminal of battery
Connected to the +ve terminal of battery
REMEMBER
The cathode must be connected to the – terminal of the battery
Session 4, Activity A

14. Uses of LEDs Digital clocks Torch DVD player
Lights at the top of the millennium spire
(Dublin monument –height 120 m)
Digital clocks
Torch
Traffic lights
Pocket lens with light
Iron

15. Using Simple Switches - Push Switch
Supplies
Circuit from previous investigation
1 push switch
Procedure
Try connecting the push switch as shown in the photo
Does it matter which way round the switch is put into the circuit? (Try it.)
Uses of push switch - camera, flashlight, etc.
Session 4, Activity B

16. Using Simple Switches - Micro Switch
Attach 3 leads as shown in the diagram
Lever can be used to ‘magnify small movements
Micro switch is very sensitive
Can be used, e.g., to sound an alarm if attached to a window with even the slightest opening.
Session 4, Activity B

17. Using Simple Switches - Micro Switch
Supplies
Circuit from previous investigation
1 micro switch
Procedure
Try connecting the
micro switch as shown
in the photo
Complete the table
below
Wires used
What happens to the lamps before the lever is pressed?
What happens to the lamps after the lever is pressed?
1 and 2
1 and 3
2 and 3

18. Using Simple Switches - Micro Switch
Wires used
What happens to the lamps before the lever is pressed?
What happens to the lamps after the lever is pressed?
1 and 2
Light off
Light on
1 and 3
2 and 3
Pins 1 and 2 are known as ‘normally open (NO)’
Pins 1and 3 are known as ‘normally closed (NC)’

19. Using a ‘Silicon Chip’
4093 silicon chip – Quad, 2-input NAND logic chip
This chip contains four logic gates, each with two inputs
It has 14 legs (pins)
Students use pins 1, 2, 3, 7 and 14
Pins 1 and 2 are inputs, pin 3 is the output, of one gate
The output depends on the inputs

20. How the Output Depends on the Inputs
Wire connects pin 2 to – of battery
Cathode connects to – of battery
Anode of LED connects to pin 3
To + of Battery
Wire connects pin 14 to + of battery
Wire connects pin 1 to + of battery
Wire connects pin 7 to – of battery
To – of battery
Supplies
Breadboard + Battery
Electrical wire
4093 silicon chip
LED
Procedure
Build the circuit shown in the photograph.
Complete the table in the workbook.
Input to pin
ON - when connected to + of battery
OFF- when connected to – of battery
Session 4, Activity C

21. Input Pattern for the 4093 Pin 1 Pin 2 Pin 3 (output) OFF ON
Input to pin
ON when connected to + of battery
OFF when connected to – of battery
Pin 1
Pin 2
Pin 3 (output)
OFF ON ON ON ON
OFF
Session 4, Activity D

22. Session 5: Electronic Engineering Il
Reed Switches
Two thin pieces of metal sealed in a vacuum in a glass tube
When a magnet is brought near the two metal contacts they are brought together and connected

23. A Reed Switch Circuit Supplies Procedure As Session 4, Activity C
Build the circuit shown in the diagram.
Bring the magnet near to the reed switch and observe what happens.
Swap the LED for a
buzzer
Session 5, Activity A

24. Making an LED Flash
To do this you need to use a capacitor and a resistor
Capacitors: Store charge and consist of two conducting surfaces separated by an insulator.
When connected to a battery a capacitor charges up until it reaches the same voltage as the battery
When a conductor, e.g., a bulb, is connected to the charged capacitor current will flow from one plate to the other
The charging and discharging of a capacitor can be slowed down by placing a resistor in series with it in the circuit. -

25. Resistors
Resistance of a circuit is how difficult it is to drive a current through it. The bigger the resistance the smaller the current that can flow for a given voltage across the circuit.
Resistance is measured in ohms (Ω). When we want to reduce the current flowing in a circuit we insert a resistor.
Some resistors are made of wire but most are made of carbon. The coloured bands tell us what the resistance of each resistor is.

26. Resistor Colour Codes Two series—4-band and 5-band Colour Value Black
4- band code
Bands 1 and 2 = first two digits of the value
band 3 = the powers of 10. Band 4 = the quality of the resistor
Gold band = 5%
Silver band = 10%.
Band 4 is separated from the other bands, to tell us at which end to start counting from
Colour
Value
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Grey
White 1 2 3 4 5 6 7 8 9

27. Making an LED flash Supplies Procedure Breadboard Battery
Capacitor
Resistor
4093 silicon chip
LED
The – leg of the capacitor goes here
Resistor 1 has one leg to pin 1, the other to pin 3
Resistor 2 has one leg to pin 3, the other to LED
Note the link wire connecting pin 1 to pin 2
For 4093BE chip an extra resistor - 1k (BrBkR) - is needed between pin3 and LED
Not required on 4093BP chip
Procedure
Build the circuit shown in the photograph
Investigate how
the flashing rate changes if you change the resistor
Session 5, Activity B See website-’Electronic Fixes’

28. Controlling a Motor Chip 2003
Pin 8 must be connected to the negative of the battery
Pin 9 must be connected to the positive of the battery

29. Controlling a Motor Supplies Procedure
Components from previous session
Electric motor
2003 chip
Procedure
Build circuit as in diagram
Use pin 1 to turn the motor on and off
Connect the motor between the +ve of the battery and pin 16
Do not allow the motor to run longer than 10 seconds at a time
Session 5, Activity C

30. Ireland
Education