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CENT-112 Fundamentals of Electricity and Electronics 1 Impurity Atoms: Trivalent: Boron (B), Aluminum (Al), Gallium (Ga), Indium (ln). Has three (3) valence.

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Presentation on theme: "CENT-112 Fundamentals of Electricity and Electronics 1 Impurity Atoms: Trivalent: Boron (B), Aluminum (Al), Gallium (Ga), Indium (ln). Has three (3) valence."— Presentation transcript:

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2 CENT-112 Fundamentals of Electricity and Electronics 1 Impurity Atoms: Trivalent: Boron (B), Aluminum (Al), Gallium (Ga), Indium (ln). Has three (3) valence electrons. –Known as an “Acceptor Impurity.” Pentavalent: Phosphorous (P), Arsenic (As), Antimony (Sb), and Bismuth (Bi). Has five (5) valence electrons. –Known as a “Donor Impurity.” Diodes

3 CENT-112 Fundamentals of Electricity and Electronics 2 –“N - Type” Material: Pure base material doped with a Donor Impurity. Majority Current Carrier: Electrons Minority Current Carrier: Holes –“P - Type” Material: Pure base material doped with an Acceptor Impurity. Majority Current Carrier: Holes Minority Current Carrier: Electrons PN Material

4 CENT-112 Fundamentals of Electricity and Electronics 3 –Old Method: Grown Crystals. –Newer Methods: Alloy Fused: N & P material made using heat / pressure. Diffused: N & P gas and heat. –Both methods are used to produce a “PN” Junction. Construction

5 CENT-112 Fundamentals of Electricity and Electronics 4 Questions Q) What is meant by a donor impurity? A) 5 valiant electrons in outer shell. Q) What are 4 examples of a donor impurity? A) Phosphorous, Arsenic, Antimony and Bismuth.

6 CENT-112 Fundamentals of Electricity and Electronics 5 Potential Hill (Junction Barrier) : Electrostatic field set up across a PN junction which prevents further combination of majority current carriers. The value of the voltage of the potential hill depends on the type of base material used during diode construction. 1. Silicon (.5 -.8V) 2. Germanium (.2V) Rated for up to 1500A / 3000V. Used primarily in Rectifiers. Diode Definitions

7 CENT-112 Fundamentals of Electricity and Electronics 6 Operations & Definitions Forward Bias: External voltage applied which opposes the potential hill, effectively reducing the width and resistance of the depletion region. => Majority Current Carriers flow through the PN junction. Reverse Bias: External voltage applied which aids the potential hill, effectively increasing the width and resistance of the depletion region. => No Majority Current Carriers flow through the PN junction.

8 CENT-112 Fundamentals of Electricity and Electronics 7 Rectifier Diode Block Diagram P Anode Cathode Potential Hill (Junction Barrier) Depletion Region N

9 CENT-112 Fundamentals of Electricity and Electronics 8 Rectifier Diode Schematic Diagram AnodeCathode

10 CENT-112 Fundamentals of Electricity and Electronics 9 Diode Forward Bias P Anode Cathode Potential Hill (Junction Barrier) Depletion Region N

11 CENT-112 Fundamentals of Electricity and Electronics 10 Diode Reverse Bias P Anode Cathode Potential Hill (Junction Barrier) Depletion Region N

12 CENT-112 Fundamentals of Electricity and Electronics 11 Characteristic Curve +I (mA) Forward Bias Reverse Bias -I (uA) Avalanche Breakdown +V a -c-V a -c

13 CENT-112 Fundamentals of Electricity and Electronics 12 Zener Diode –The Zener diode is a heavily doped diode which, as a result of doping, has a very narrow depletion region. This allows the diode to be operated in the reverse biased region of the characteristic curve without damaging the PN junction. –“Zener Effect”: The area of Zener diode operation (<5V) where the Diode maintains a constant voltage output while operating reverse biased. –“Avalanche Effect”: >5V applied to the diode while reverse biased which tends to cause the diode to eventually breakdown due to heat generation within the lattice structure of the crystal.

14 CENT-112 Fundamentals of Electricity and Electronics 13 Zener Diode Schematic Symbol AnodeCathode

15 CENT-112 Fundamentals of Electricity and Electronics 14 Characteristic Curve Operating Region Reverse Bias Forward Bias + V a - c- V a - c I (mA) I (uA)

16 CENT-112 Fundamentals of Electricity and Electronics 15 Zener Operation Ratings:.25V to 1500V Used in SSMG / SSTG AC voltage regulator for the reference circuit. When a higher constant voltage is desired, the zener diodes will be “Stacked” together in series and their voltages will add together to make the higher desired voltage. This is the case in the SSMG / SSTG AC voltage regulators where four (4) 6v zener diodes are stacked to provide a 24V reference to the comparison circuit.

17 CENT-112 Fundamentals of Electricity and Electronics 16 Zener Diode Voltage Regulator R1 CR1 Vin Vout

18 CENT-112 Fundamentals of Electricity and Electronics 17 Signal Diode Same construction as the Rectifier Diode except that it is designed to operate with a very short “reverse recovery time” to allow it to rectify high frequency AC inputs.

19 CENT-112 Fundamentals of Electricity and Electronics 18 Power Supplies Components and their function –Transformer - Receives the AC input from the distribution system and either steps up or down the voltage. –Rectifier - Converts the AC input voltage from the transformer to a pulsating DC voltage. –Filter - Smoothes out the DC pulsations or ripple received from the rectifier. –Regulator - Receives a smoothed DC voltage from the Filter Stage and produces a steady DC voltage to be used by electronic circuitry.

20 CENT-112 Fundamentals of Electricity and Electronics 19 Half - Wave Rectifier V OUT V IN 1 : 1 T1 CR1 R1

21 CENT-112 Fundamentals of Electricity and Electronics 20 Positive half-cycle the diode is Forward Bias (FB), negative half-cycle the diode is Reverse Bias (RB). Half - Wave Rectifier Operation V DC = V PK X.318 Where: V DC = Average DC voltage V PK = Peak input voltage.318 = Constant

22 CENT-112 Fundamentals of Electricity and Electronics 21 Full - Wave Rectifier V OUT V IN 1 : 1 T1 CR1 R1 CR2

23 CENT-112 Fundamentals of Electricity and Electronics 22 Positive half-cycle, 1 diode is FB, negative half-cycle the other diode is FB. Full - Wave Rectifier Operation V DC = V PK X.637 Where: V DC = Average DC voltage V PK = Peak input voltage.637 = Constant

24 CENT-112 Fundamentals of Electricity and Electronics 23 Full – Wave Bridge Rectifier V OUT V IN 1 : 1 T1 CR1 R1 CR2 CR3 CR4

25 CENT-112 Fundamentals of Electricity and Electronics 24 Positive half-cycle, 1 diode is FB, negative half-cycle the other diode is FB. Full - Wave Bridge Rectifier Operation V DC = V PK X.637 Where: V DC = Average DC voltage V PK = Peak input voltage.637 = Constant

26 CENT-112 Fundamentals of Electricity and Electronics 25 Filters A filter uses the characteristics of Inductors and Capacitors to smooth the pulsating DC waveform supplied by the Rectifier. –Types High Pass - A series RC filter whose output is taken from the resistor. Series / Parallel - A filter configuration which uses combinations of capacitors and inductors to smooth the voltage and current pulsations from the rectifier output.

27 CENT-112 Fundamentals of Electricity and Electronics 26 Rapid charge time constant for filter capacitors and inductors. Slow discharge time constant for filter capacitors and inductors. Ideal filter characteristics

28 CENT-112 Fundamentals of Electricity and Electronics 27 Capacitor Filter Configuration RBRB C1C1 V IN V OUT Capacitor Input Filter Schematic Diagram

29 CENT-112 Fundamentals of Electricity and Electronics 28 Capacitor Filter Operation Charge RC time constant is developed from the internal resistance of the rectifier diodes and the capacitance of the filter capacitor. The net result is that the low resistance of the rectifier diodes develop a rapid charge RC time constant. Discharge RC time constant is developed from the filter capacitor and the load resistance. Since the load resistance is rather large, the discharge RC time constant is somewhat long. R B is called the “Bleeder Resistor” because it provides a path for the filter capacitor(s) to discharge when power is removed from the circuit. R B has a very large resistance and usually draws <10% of normal operating current.

30 CENT-112 Fundamentals of Electricity and Electronics 29 LC Choke Filter Configuration LC Choke Filter Schematic Diagram RBRB C1C1 V IN V OUT L1L1

31 CENT-112 Fundamentals of Electricity and Electronics 30 LC Choke Filter Operation Charge RC time constant is developed from the internal resistance of the rectifier diodes, the Low DC resistance of the inductor (L1), and the capacitance of the filter capacitor. The net result is that the low resistance of the rectifier diodes and inductor (L1) develop a rapid charge RC time constant. Discharge RC time constant is developed from the filter capacitor and the load resistance. Since the load resistance is rather large, the discharge RC time constant is somewhat long. The Inductor acts to smooth out the current pulsations produced by the rectifier and / or transformer stage of the power supply.

32 CENT-112 Fundamentals of Electricity and Electronics 31 RC PI Filter Configuration RC PI Filter Schematic Diagram RBRB C2C2 V IN V OUT C1C1 R1R1 V OUT(C1) V OUT (C2) Charge Path Discharge Path

33 CENT-112 Fundamentals of Electricity and Electronics 32 RC PI Filter Operation First Capacitor provides most of the filtering action. Second Capacitor Provides additional voltage filtering. Resistor limits current flow to the desired value and establishes the RC time constants for both filter capacitors.

34 CENT-112 Fundamentals of Electricity and Electronics 33 LC PI Filter Configuration LC PI Filter Schematic Diagram RBRB C2C2 V IN C1C1 L1L1 V OUT(C1) V OUT (C2) Charge Path Discharge Path

35 CENT-112 Fundamentals of Electricity and Electronics 34 LC PI Filter Operation First Capacitor provides most of the filtering action. Second Capacitor Provides additional voltage filtering. Inductor opposes changes in current flow to reduce current spikes and establishes the RC time constants for both filter capacitors.

36 CENT-112 Fundamentals of Electricity and Electronics 35 Voltage Regulators R1 CR1 Vin Vout –Series Regulator Acts as a variable resistor in series with the load. –Zener Diode Voltage Regulator Schematic

37 CENT-112 Fundamentals of Electricity and Electronics 36 Voltage Regulator Operation R1 CR1 Vin Vout V IN V OUT

38 CENT-112 Fundamentals of Electricity and Electronics 37 Transistor Voltage Regulators Vin Vout

39 CENT-112 Fundamentals of Electricity and Electronics 38 OPAMP Voltage Regulators Vin Vout - +


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