Day 1 - TTEC4847 - Vehicle Electrical and Electronics

It was an exciting day for me to study in second semester at Mt.Albert Campus.
When I finish this course, I hope that I have more knowledge in Autotronics than before.

Marks:
 4 theory quizes(40%) - every Friday starting from 12th Aug
 Portfoilio/Blog(60%)

To finish this course, we need to finish First aid 2 days course.

Format of Blogs:
 1. Theory
 2. Practical exercise
 3. Good and bad results e.g why is this bad or good results?

Internet sites:
Moodle : http://moodle.unitec.ac.nz/
Ebay: http://www.ebay.com/  search multimeter VC99
Google: http://www.google.com/ search pocket nano dso oscilloscope

Theory:

Resistor

Resistors offer opposition to current, dissipatig the opposed power as heat. The basic type of resistor is the carbon composition resistor. In addition to the resistance value, the power dissipating capability of a resistor is measured in watts. Standard carbon comps are rated at 1/4 watt.

Color coding: Each number is represented by a color.

Black	0
Brown	1
Red	2
Orange	3
Yellow	4
Green	5
Blue	6
Purple/violet	7
Grey	8
White	9

The tolerance bands at the far end are as follows:
Brown: ±1%
Red: ±2%
Gold: ±5% (the measured value should be no more than 5 percent high or low of the stated resistance)
Silver: ±10%

Manufacturers could not produce resistors in every possible value, so initially only the most common values were produced. One of the popular series are as follows:

E12 Series(10% tolerance)

1.0 Ω(1R)	10 Ω (10R)	100 Ω (100R)	1000 Ω (1K)
1.2 Ω	12 Ω	120	1200 Ω
1.5 Ω	15 Ω	150 Ω	1500 Ω
1.8 Ω	18 Ω	180 Ω	1800 Ω
2.2 Ω	22 Ω	220 Ω	2200 Ω
2.7 Ω	27 Ω	270 Ω	2700 Ω
3.3 Ω	33 Ω	330 Ω	3300 Ω
3.9 Ω	39 Ω	390 Ω	3900 Ω
4.7 Ω	47 Ω	470 Ω	4700 Ω
5.6 Ω	56 Ω	560 Ω	5600 Ω
6.8 Ω	68 Ω	680 Ω	6800 Ω
8.2 Ω	82 Ω	820 Ω	8200 Ω (8K2)

N.B:Choose a resistor by resistance and wattage.

Ohm's law :  The current flowing between any two points in an electric circuit is directly proportional to the potential difference between these points and inversely proportional to the resistance of the circuit between these points.

V = IR ( I = V / R, R = V / I)
Ohms: the resistance to the flow of electrons
Ampere: current flowing in the circuit
Volt: unit of pressure, electromotive force

Power = EMF x I (i.e P=VI)
There are two kinds of current flows. They are conventional current and electron flow.
Conventional current: Current flows from positive side of the source to negative side of the source.
Electron flow: Electrons flow out of the negative terminal into the positive side of the source.

Practical
Experiment No.1 Identifying, Testing and Troubleshooting Semiconductor Componets

Record the values in the chart below:

Value (colour codes )	Value (multimeter)
100000(100k)	94.7k
470	469
10000(10k)	10k
100	99
5600(5.6k)	5.5k
270	267

Choose two resistors and record their individual ohm resistance value measured with a multi-meter:

             Resistor 1      5.52kΩ                    Resistor 2        10kΩ

Put these two resistors together in series (end to end, one right after another) calculate and then measure their combined value. Show workings:

Calculated value 1 and 2 in series:     15.52kΩ

Measured value 1 and 2 in series:       15.51kΩ

Put these two resistors together in parallel (connect both ends when they are side-by-side). Calculate and then measure their combined value. Show workings:

Calculated value 1 and 2 in parallel:       3.56kΩ

Measured value 1 and 2 in parallel:        3.56kΩ

            

What principles of electricity have you demonstrated with this? Explain:

In series circuit, the total resistance of the resistors are the sum of the resistance of each resistors.
(e.g RT = R1 + R2)
In parallel circuit, the total resistance of the resistors are smaller than the smallest resistance of the resistors.
(e.g 1/RT = 1/R1 + 1/R2)

Experiment No. 2 Diodes

Exercise: Using a multimeter, identify the anode and cathode of the diode and the LED.

	Voltage drop in forward Biased Direction.	Voltage drop in reverse biased direction
LED	1.520V	1
Diode	0.700V	1

Explain how you could identify the cathode without a multimeter

LED: In a top view, it has a flat surface. That flat side is the cathode.

Diode: On the component, there is a band. That side is the cathode.

What do you observe? Explain briefly.
In my opinion, the purpose of this experiment is for learning voltage drop. The voltage drop across the diode is about 0.7V but the voltage drop across the LED is about 1.8V. Therefore, the current flowing in each circuit is different.

Exercise: For Vs=5V, R= 1KΩ, D= 1N4007 build the following circuit on a breadboard.

Calculate first the value of current flowing through the diode, now measure and check your answer?

Show your working
Calculated      I = (5 - 0.7) / 1k
                         = 4.3mA
Measured       5.34mA

Calculate the voltage drop across the diode, now measure and check your answer?

Calculated     0.7V
Measured      0.68V

Using the data sheet given in Table 1 above,

What is the maximum value of the current that can flow through the given diode?
1A
For R = 1KΩ.  What is the maximum value of Vs so that the diode operates in a safe region?
1000V

Replace the diode by an LED & calculate the current, then measure and check your answer?

Calculated    I = (5-1.8) / 1k = 3.2mA (By assuming VD=1.8V)
Measured   4.14mA