EXPERIMENT No. 1
Identifying, Testing and Troubleshooting Semiconductor Components
Identifying, Testing and Combining Resistors
Fig 1:
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Fig 2
Obtain 6 resistors of different values. You are then going to determine their value two ways:
· Use the colour code to calculate the value of the resistor.
· Include the maximum and minimum tolerance value of each resistor
· Then measure the resistor value with a multimeter.
Record the values in the chart below:
Value (colour codes ) | Value (multimeter) |
270-13.5 | 266 |
100 + - 5x | 98 |
10k + - 3000 | 93.5k |
470 + - 4.7 | 470 |
5600 + - 180 | 5.53k |
We chose different type of resisitors, then using the resistor colour band and using the chart above we found out the resistance of the resistors in Ohm's(Ω), and checking the resistors tolerance, then using a multimeter to check that the calculations we did were correct . Then we took two resistors and wired them into series to meausure the total resistance of the resistors in series, then we wired them up into parallel to and measure the resistance and the total resistance should be lower than the lowest resistance because more consumers are added into a parallel cicuit and the resistance goes down and the current goes up, but in the series circuit they only have one path to follow because they go through all the resistors creating higher resistance making less current flow.
Choose two resistors and record their individual ohm resistance value measured with a multi-meter:
Resistor 1 266 Ω Resistor 2 098 Ω
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: 364 Ω
Measured value 1 and 2 in series: 364 Ω
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: 61 Ω
Measured value 1 and 2 in parallel: 72 Ω
What principles of electricity have you demonstrated with this? Explain:
That the resistor slows down the current flowing through and the different types of resistors limit the current depending on the resistance of the resistor.
EXPERIMENT No. 2
DIODES
Fig 3 - Diode Symbol & Physical component
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Fig 4 – Diode symbol and P.N. junction
A diode has the characteristics of:
· An insulator when current tries to flow in one direction.
· A conductor when current flows in the other direction.
Components: 1 x diode, 1 x LED
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 | 20.9 | 6.1 |
Diode | 76 | 26 |
Explain how you could identify the cathode without a multimeter
On the led the longer leg will be the postive which is Anode , if the legs have been cut there is a flat side which will indicate that it is the cathode side.
On the diode the cathode side will be after the silver band.
On the led the longer leg will be the postive which is Anode , if the legs have been cut there is a flat side which will indicate that it is the cathode side.
On the diode the cathode side will be after the silver band.
Table 1: Data sheet of 1N4007 is as follows
Absolute Maximum Ratings, TA = 25OC | |||
Symbol | Parameter | Value | Units |
IO | Average rectified current @ TA = 75oC | 1.0 | A |
PD | Total device dissipation Derate above 25oC | 2.5 20 | W mW/OC |
 | Thermal resistance, Junction to Ambient | 50 | OC/W |
 | Storage Temperature Range | -55 to + 175 | OC |
 | Operating Temperature Range | -55 to + 150 | OC |
VRRM (PIV) | Peak repetitive reverse voltage | 1000 | V |
Components: 1 x resistor, 1 x diode. 1 x LED
Exercise: For Vs=5V, R= 1KΩ, D= 1N4007 build the following circuit on a breadboard.
Fig 5
Calculate first the value of current flowing through the diode, now measure and check your answer?
Show your working
Calculated Measured
52x10000x1 0.005
520.0005
520.0005
Is the reading as you expected; explain why or why not?
Yes, accordings to ohms law the didode should be the same
Calculate the voltage drop across the diode, now measure and check your answer?
Calculated Measured
N/A 0.068
Using the data sheet given in Table 1 above,
What is the maximum value of the current that can flow through the given diode?
The maximum current that can flow is 1 Amp , aslo the current slightly changes because of different voltage drops
For R = 1KΩ. What is the maximum value of Vs so that the diode operates in a safe region?
The value of the voltage is 1000v
Replace the diode by an LED & calculate the current, then measure and check your answer?
Calculated Measured
0.005Amps 0.005Amps
What do you observe? Explain briefly.
The current is slightly different because of voltage drops
EXPERIMENT No. 3
Components: 2 x resistors, 1 x 5V1 400mW Zener diode (ZD).
Exercise: Obtain a breadboard, suitable components from your tutor and build the following circuit.
Fig 6
For R= 100Ω and RL= 100Ω, Vs= 12 V.
What is the value of Vz?
4.78
Vary Vs from 10V to 15 V
What is the value of Vz
10v=4.75v 15v=5.14
Explain what is happening here
The voltage flowing through the diode increase when the supply voltage is increased
What could this circuit be used for?
To regulate the voltage in a circut.
Reverse the polarity of the zener diode.
What is the value of Vz? Make a short comment why you had that reading.
The reading at Vz when it was reversed was 0.8volts . This is because it has more resistance.
.
EXPERIMENT No. 4
Components: 1 x resistors, 1 x 5V1 400mW Zener diode, 1X Diode1N4007 .
Exercise: Obtain a breadboard, suitable components from your tutor and build the following circuit.
Vs=10 & 15v, R=1K ohms
Fig 7
10 Volts 15 Volts
Volt drop V1: 0.002 v 0.003v
Volt drop V2: 0.003v 0.004
Volt drop V3: 0v 0.003v
Volt drop V4: 0v 0v
Calculated current A: 0.001 Amps 0.015Amps
Describe what is happening and why you are getting these readings:
Describe what is happening and why you are getting these readings:
When the voltage increases all of the components use the required amount of voltage to power them up which leaves the rest of the voltage to be consumed by the resistor
EXPERIMENT No. 5
The Capacitor
The capacitor stores electric charge.
A capacitor consists of two metal plates very close together, separated by an insulator. When connected 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 capacitance of the capacitor, which is measured on Farads (F).
Types of capacitor:
Non-electrolytic capacitor | |
  | · Fairly small capacitance - normally about10pF 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 50000mF · 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. |
Identifying Capacitor “Size”
If the Farad “size” is not printed on the capacitor, you may find an EIA code listed. Use the table below to figure out the capacitance
μF | nF | pF | EIA Code |
0.00001* | 0.01 | 10 | 100 |
0.0001* | 0.1 | 100 | 101 |
0.001 | 1.0 (1n0) | 1,000 | 102 |
0.01 | 10 | 10,000* | 103 |
0.1 | 100 | 100,000* | 104 |
1.0 | 1000* | 1,000,00* | 105 |
10.0 | 10,000* | 10,000,00* | 106 |
x 0.000001 F x 5 = 5 seconds to charge to applied voltage. This can x 1 μF x 5 = 5 seconds. UNITEC Applied Technology Institute - 14 - 02/02/2010 4824 lab workbook First, calculate how much time it would take to charge up the capacitor. Then, connect Label the axis of each graph:
Capacitance: 100μF Resistance: 1kΩ
Capacitance:100μF Resistance:0.1kΩ
Capacitance:100μF Resistance: 0.47kΩ
Capacitance:330μF Resistance: 1kΩ
How does changes in the resistor affect the charging time?
The lower the resistance the faster it will take to charge the capacitor , the lower the resistance the more current will get through and the quicker the time charge .
How does changes in the capacitor affect the charging time ?
The higher the capacitance of the capacitor the more charge it will hold , and the more time it will take
Meter Check of a TransistorDiode test (V) meter readings
Transistor number VBE VEB VBC VCB VCE VEC
PNP 0L 0.725 OL 0.720 OL OL
NPN 0.688 OL OL 0.686 OL OL
Transistor number VBE VEB VBC VCB VCE VEC
PNP 0L 0.725 OL 0.720 OL OL
NPN 0.688 OL OL 0.686 OL OL
There are two different types transistors , the NPN and the PNP. A transistor has 3 Legs one is called the base , the other is the collector and emittor.
©
Fig 8-Capacitor Charging Circuit
Components: 1 x resistor, 1 x capacitor. 1 x pushbutton N/O switch.
Reference:
Unitec moodle/ Workbooks
Previous Blog
Reference:
Unitec moodle/ Workbooks
Previous Blog
Exercise
the circuit as shown above. Measure the time taken by the capacitor to reach the applied voltage
on an oscilloscope. Fill in the chart below. Also draw the observed waveforms in the graphs below,
filling the details on each one.
Note: you will need to adjust the time base to enable you to observe the pattern.
circuit capacitance resistance calculated observed
number (uF) (k ohms) time(ms) time (ms)
1 100 1 500 500
2 100 0.1 50 45
3 100 0.47 253 25
4 330 1 1650 1650
4 330 1 1650 1650
Your doing well below what you are capable of here. Make sure you check that your answers are correct before posting them. I would like to see more thoery/reflection behind some components in your next blog
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