1. Diodes, Transistors and Tubes

2. Silicon Semiconductors

3. Doped Semiconductors

4. P-N Junction Extra holes combine with extra electrons to form depletion zone

5. Forward Bias Diode conducts only when it is forward-biased.

6. Reverse Bias

7. Diodes let current flow in only one direction.

8. Diodes Diode conducts only when it is forward-biased. Electrons flow from cathode to anode (ie NOT the direction of the arrow) demodulation is one important application for diodes in recovering info from transmitted signals (more about that in the modulation and transmitters session) What else might be a use of a diode?

9. Rectification Diode use: rectification, ie changing alternating current (AC) to pulsating direct current (DC) Diode lets through current only in one direction, so if an alternating current is applied to the anode of a diode the cathode would have a pulsating direct current. What other diodes are used in power supplies?

10. Zener diodes Zener diodes work in the forward biased direction as a normal diode would, but they also allow current to flow in the reverse way when the voltage is above the breakdown voltage, and their breakdown voltage is precisely known. used as voltage regulators, ie to regulate or maintain a constant voltage current can flow in reverse biased direction, but only if it is over a certain voltage, the breakdown voltage What other kind of diodes?

11. LED - light emitting diode Semiconductor device that glows different colours depending on chemical composition

12. Amplification or Gain Amplification increases voltage, current, and/or power “Amplification” is equivalent to “gain” Amplification is opposite of attenuation or loss, and an amplifier doesn’t have loss (since the exam talks about that a lot) A circuit designed to increase the level of its input signal is called an amplifier To increase the level of - very weak radio signals, use RF amplifier - very weak signals from a microphone, use an audio amplifier What is amplification? What sort of device might be used?

13. Transistors

14. Bipolar Transistors NOT USED

15. Bipolar Transistors Transistors can be of PNP or NPN type A transistor can amplify a small signal using low voltages. (tubes can amplify but need high voltages, but tube not option in exam) A basic semiconductor amplifying device is the transistor (exam throws tubes in there, but they are not semi- conductors) The three leads are base, collector emitter One example bipolar transistor would be a “general purpose audio NPN device” A transistor can be destroyed by excessive heat.

16. Field Effect Transistors

17. Two basic types are N and P channel functions are: – gate controls the conductance of the channel – source is where charge carriers enter the channel – drain is where charge carriers leave channel The field-effect transistor is the semiconductor with the characteristics most similar to a triode vacuum tube. To reduce current, increase reverse-bias voltage.

18. Triode Vacuum Tube Electrons released from cathode via thermionic emission Electrons flow to positively charged anode Negative voltage on grid repels electrons, decreases flow Positive charge on grid attracts electrons, increases flow

19. Triode Vacuum Tube Inside the envelope is a vacuum. Feature common to both transistors and tubes is that they can amplify signals. A triode vacuum tube might be used because instead of a transistor because it may be able to handle higher power. Can amplify a small signal but must use high voltages (transistor doesn’t need high voltages) Parts – highest positive potential – plate – cylinder of wire mesh – grid (one grid!) – element furthest from plate is – filament Cathode emits electrons Most similar to a Field Effect Transistor

20. Equivalencies The exam has a bunch of “closest” comparisons

21. Distortion If an amplifier becomes non-linear, the output would become distorted (there are other kinds of distortion…)

22. The End

23. Schedule DateTopicInstructor Feb 20 - 9 AMChapter 2: Basic TheoryRob Striemer (VE4SHS) Feb-20Chapter 3: Ohm’s Law & PowerRob Striemer Feb-20Chapter 4: Inductors & CapacitorsRob Striemer Feb 20 - 1 PMChap. 1: Introduction to Amateur RadioDylan Fijal (VA4DFJ) Feb-20Chapter 12: Q codes, phonetics, emerg comms, etc.Dylan Fijal Feb-20Chapter 17: Regulations, Towers, etc.Dylan Fijal Feb 27 - 9 AMChapter 5: Wavelength, Frequency and BandsCollin Stanners (VE4CST) Feb 27 - 9 AMChapter 6: PropagationCollin Stanners Feb 27 - 9 AMCh. 7: Transmission LinesCollin Stanners Feb 27 - 1 PMCh. 10: Power SuppliesPeter Toth (VE4TTH) Feb 27 - 1 PMChapter 11: Setting up an Amateur Radio StationPeter Toth Feb 27 - 1 PMChapter 12: Operating an Amateur Radio StationPeter Toth March 5 - 9 AMChapter 8: AntennasTina Tenbergen (VA4THN) Mar-05Chapter 8: AntennasTina Tenbergen Mar-05Chapter 9: Diodes, Transistors and TubesTina Tenbergen March 5 - 1 PMChapter 13: Modulation and TransmittersJim Townsend (VE4CY) Mar-05Chapter 14: ReceiversJim Townsend Mar-05Practice Exam March 12 – 9 AMChapter 15: Radio Frequency InterferenceBob Jacobs (VE4RCJ) Mar-12Chapter 16: SafetyBob Jacobs Mar-12Review March 12 - 1 PMReview & Practice ExamRob Striemer March 19 – 9 AMIndustry Canada Final Exam 9:00 AMAdam Romanchuk March 19 – 11 AM11:00 AM - workshop: How to get started, tips, etc.