TTEC4824 Automotive Electronics

 Electricity:  Current(Amperage) \ Resistence(Ohms) \ Volts \ Power(Watt)

Formula of electricity: Amperes = Volts / Ohms

                        Ohms    = Volts / Amperes

                        Volts   = Amperes * Ohms

                        Watts   = Volts * Amperes

Resistor

What is the resistor?
A linear resistor is a two terminal, linear,passive electronic component that implements electrical resistance as a circuit element. The current flowing through a resistor is in a direct proportion to the voltage across the resistor's terminals.
The ratio of the voltage applied across resistor's terminals to the intensity of current flowing through the resistor is called resistance.


How does it work?
A resistor in the circuit we have to read the specification before and choose the right resistor use to the circuit, because if use small one to the high power circuit it will be over heat and fusing so it wouldn't be protect the circuit. But if use large resistance to the low power circuit it will be protect too much electricity throw the circuit so the electrical equipment wouldn't work very well.


How to read the resistor?(Resistor color code)

        


Calculate
Series circuit:  Rt= R1+R2+R3+..
Parallel circuit: Rt=R1*R2/R1+R2


Reflection
Resistor can block the current flow throw the circuit. 
In series circuit Rt always large than each resistor.
In parallel circuit Rt always smaller than the small resistor.

Diodes

What is the diode? 

In electronics a diode is a two terminal electronic component.

How does it work? 

The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forward direction), while blocking current in the opposite direction (the reverse direction).

Some diode symbols:

Diode	Zener diode	Schottky diode	Tunnel diode
Light-emitting diode	Photodiode	Varicap	Silicon controlled rectifier

(from: http://en.wikipedia.org/wiki/Diode#Types_of_semiconductor_diode)

We use three types diodes for this experiment: Diode\ Zener Diode\ LED.

1    Diodes & LED: We use the multimeter,identify the anode and cathode of the diode and the    LED. We found when we test voltage drop in forward biased direction we could read the voltage drop of the LED is above 1.80V and the diode is above 0.6V, but when we test voltage drop in reverse biased direction we read the voltage drop of the LED and diode same as infinity. It's mean the current only flow one direction in the diodes, and different diode has different limited voltage drop.

 

2    Zener diode: from experiment we found the zener diode only can flow through the voltage drop in reverse and constant.

3    Experiment reflection: we use 10V and 15V battery supply, a resistor, a diode and a zener diode. In this experiment we checked the voltage drop of each components and we found the voltage drop on the diode and the zener diode always same as the individual test so is mean on the circuit the diodes can block the current flow throw. The Vs only change the resistor's voltage drop.

Transistor

What is transistor?

A transistor is a semiconductor device used to amplify and switch electronic signals. It is composed of a semiconductor material with at least three terminals for connection to an external circuit.

How to check identify of the transistor?

We use a multimeter turn it to test diode, than use positive leg and negative leg to find which leg is base of the transistor. Because the collector disconnect the emitter but them both connect the base, also we can find the type of transistor PNP or NPN.

How to check the collect and the emitter?

We use a multimeter and set it to diode test, we test base leg with the other two legs and the higher reading is the emitter but the other leg is the collector.

Experiment

From this experiment I checked the voltage between the base and emitter, and between the collector and emitter. I know the 10KΩ can block almost voltage drop but the less voltage drop can flow through between the base and emitter, and it can open the gate, than the collector would connect the emitter so the voltage drop can flow through between collector and emitter.

From this experiment we used a low ohms resistor for Rc and we changed high ohms resistors for Rb between 2K2Ω to 1MΩ, and we checked the voltage drop of the Vbe and the Vce, also we checked the amperage of the base and the collector. We found the Vbe and Ib doesn't change too much when we change the Rb, but the Vce has changed also the current changed of the base and collector. When the Rb is lower the Vce is lower but the Ic is higher, and when the Rb is higher the Vce goes higher but the Ic is lower.

It's told us when the Rb get high resistance the base couldn't get enough current flow through because the high resistance block almost current, so the collector couldn't flow through the current to the emitter but the Vce has high voltage drop. And if the Rb get less resistance so the circuit can flow through more current to the Ib and when the Ib get enough current throw it will be open the gate and collector could connect emitter throw more current.

Capacitor


The capacitor stores electric charge.
A capacitor consists of two metal plates very close together, separated by an insulator. When commected to a battery or power source electrons flow into the negative plates and charge up the capacitor.The charge remains there when the battery is removed. The charge stored depends on the "size" or the capacitor, which is measured on Farads


Types of capacitor:

- Non-electrolytic capacitor: Fairly small capacitance-normally about 10pF to 1mF

                              No polarity requirements-they can be inserted

                              either way into a circuit

                              Can take a fairly high voltage.

- Variable capacitor: Adjustable capacitor by turning a knob-similar to variable 

                      resistors.

                      The maximum capacitance available is about 200pF.

                      Used in radios.

- Electrolytic capacitor: Large capacitances - 1mF to 50,000mF

                   Warning: These must be corrected the right way round(polarity)

                   or They can explode- the white terminal on the diagram above

                   signifies positive.

                   Black stripe with "-" shows which terminal is the negative

                   (Usually the short one)

                   Low voltage rating-from 25 - 100V DC

                   They have a significant leakage current - this means that they 

                   will lose the charge stored over time.

- Tantalum capacitor:These have the same properties as the Electrolytic capacitor

                     but they are physically smaller & have lower leakage. As a

                     result, though they are more expensive.