• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Transistors in Switch and Amplifier Configurations.

Extracts from this document...

Introduction

ASSIGNMENT 2

Transistors in Switch and Amplifier Configurations

Introduction:

Transistors are electronic devices usually used as amplifiers or oscillators in communications and computer systems. They consist of a tiny piece of semiconducting material, usually silicon or germanium, to which three or more electrical connections are made. The basic components of the transistor are similar to those of a triode vacuum tube and include an emitter, which corresponds to the heated cathode of the triode tube as the source of electrons. The transistor was developed by American physicists John Bardeen, Walter Houser Brattain and William Bradford Shockley.

This assignment requires us to carry out a number of tasks. For the first stage of the assignment, I will be performing four tests relating to the BC147 transistor to determine its characteristics. Graphs will be plotted with the results gained from this. Then I will carry out an experiment relating to a transistor switch circuit, answering a few questions relating to the experiment.

        Another experiment will be performed for the third part of the assignment, this time relating to the common emitter amplifier.

...read more.

Middle

0.069A

IB = IC / HFE = 0.069 / 96 = 7.19 x 10-4A

R = (VCC – VBE) / IB

R = (12 – 0.74) / 7.19 x 10-4 = 15666Ω

RB(a) = 15666 – 1000 – 10000 = 4666Ω

        Since RB(a),(b),(c) are known values, the calculation will reflect this before your final choice for RB is made.

        Now complete the following tests:

TEST 1: Adjust the potentiometer (RB(c)) to achieve the calculation as  measured on an ohmmeter. Apply the power supply and record the readings of the various meters. If VCE (sat) (or a lower value) can’t be achieved, is RB(a) to high a value?

IC (sat) = 68.1mA

IB (sat) = 0.705mA

VCE (sat) = 0.74v

VBE (sat) = 0.24v

TEST 2: State the practical value of HFE using the recorded test figures. State the percentage error between this and the original value of HFE.

HFE = IC / IB

HFE = 68.1 / 0.705 = 96.6

% Error = (Calculated HFE / Measured HFE) x 100%

% Error = (96.6 / 96) x 100%

% Error = 100.625 – 100 = 0.625%

TEST 3: Determine the maximum value that VCE may rise to, before there is a significant fall in the collector current.

VCE = 1.90v

QUESTION 1: When RB(c) was adjusted, at what point would a power rating for the transistor need consideration.

More current flows as the voltage is decreased. Therefore, the lamp will brighten.

...read more.

Conclusion

order:0px solid #000000;width:1.33px;height:37.33px;">image22.png

image48.pngimage47.pngimage48.png

image50.pngimage51.png

image22.pngimage22.pngimage22.pngimage22.png

image16.pngimage52.pngimage53.pngimage54.png

image56.pngimage56.png

image57.png

image58.pngimage59.pngimage04.png

image63.pngimage62.pngimage59.pngimage60.png

image59.png

image64.pngimage31.pngimage65.pngimage66.png

image48.png

image67.png

image69.png

image70.png

  1. Unijunction Transistor (UJT)

image71.png

image22.pngimage46.pngimage72.png

image73.pngimage48.png

image03.png

image04.png

image05.pngimage07.pngimage06.png

image04.pngimage08.pngimage09.png

image11.pngimage12.png

This is one of the simplest oscillator circuits based on a unijunction transistor. In the above circuit, the potential difference across the capacitor gradually builds up and is released almost instantly. This type of oscillator is known as a ‘relaxation oscillator’.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Electrical & Thermal Physics essays

  1. Peer reviewed

    Test of the reed switch capacitors in series and in parallel

    3 star(s)

    The set-up was same as the first experiment. Without changing the p.d., the frequency was changed in steps from 100Hz to 400Hz and the current in each case was read. The results were then tabulated. Results Measuring capacitance The results were recorded as shown as below: Capacitance C = 0.22�F Frequency f = 400Hz P.d.

  2. Light notes

    An object inside the focus has a virtual image because light does not pass through the place where the image is formed. Reflected light seems to have come from behind the mirror in straight lines. Virtual images formed by concave mirrors are upright, enlarged and seem to be behind the mirror.

  1. Light and matter notes

    Electrons have wavelength of around 10-10 m. When electrons are aimed at crystals, the layers of atoms act as gaps for diffraction and the emerging electrons paint a diffraction pattern like light does. Energy Levels of Electrons Even though an orbiting electron is an accelerating charge and should give off

  2. Objective: l To rectify ...

    Filtered and Smoothed Full-wave Rectification (Figure C25.4) After using the storage capacitor, the output voltage still contains small ripples. In order to have a steady voltage, a smoothing inductor and a smoothing capacitor are used. The smoothing inductor has a high reactance to block the alternating voltage.

  1. Investigating the Smoothing Effect of a Capacitor on a Resistive Load

    of the equation and the units of the equation of capacitance to see if they balance; C=Q V Where the unit of capacitance is: CV-1 The s.i unit of current is amps, however using the definition of current, the amount of charge that flows past a point when a current

  2. Practical Project (2863/02): The Characteristics of a Shunt Wound Motor

    It would also be extremely difficult to judge at what time the weight had reached a steady speed. Preliminary Experiment For my preliminary experiment, I had to test how much strain the leather straps could cope with. I tested the apparatus at increasing tensions, and discovered that over 11N the straps became very hot and began to smoke.

  1. AC Generator

    Also from the formula... Torque = nBIAcosx Where: n = number of coils B = strength of the magnetic field I = amount of current A = the area of the coil ...we can clearly see how if we increased the torque, meaning the faster the velocity of relative motion between the coil and the magnets, then the current (I)

  2. Choosing a light source

    Lesson 4, 5 & 6: During these lessons I started and continued to finish of my calibrations of my graphs and also my conclusions for all the light bulb sources that I investigated. (This is when I found out that my results were accurate because it formed the calibration graphs I was looking for).

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work