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Neelain University Faculty of Engineering Third Class

Neelain University Faculty of Engineering Third Class. Electronic Circuits I Lecture 1 Lecturer: Nasreen Ahmed Mekki www. 2013. Exam, LAB & Assignments degrees. LAB: 15%. Assignments : 10%. Final Exam: 75%. Syllabus. Rectifier Circuits. Filters. Clippers. Clampers. Diode.

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Neelain University Faculty of Engineering Third Class

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  1. Neelain UniversityFaculty of EngineeringThird Class Electronic Circuits I Lecture 1 Lecturer: Nasreen Ahmed Mekki www. 2013

  2. Exam, LAB & Assignments degrees • LAB: 15%. • Assignments: 10%. • Final Exam: 75%

  3. Syllabus • Rectifier Circuits. • Filters. • Clippers. • Clampers. • Diode. • BJT Common Base Circuit. • BJT Common Emitter Circuit.

  4. Syllabus • BJT Common Collector Circuit. • BJT, FET and MOSFET Amplifiers. • Amplifiers Coupling. • Multistage Amplifier. • Power amplifiers. • Push-Pull Amplifier. • Darlington Amplifier. • RF, Video and toned Amplifier.

  5. Lecture1 Rectifier Circuits

  6. Rectifier • One of the most important application of diode. • Rectifier circuits are two-port networks that capitalize on the nearly one-way conduction of the diode. • An ac voltage is impressed upon the input port, and a dc voltage appears at the output port.

  7. Electronic devices work only with DC voltage. • The main supply is 220/110 AC voltage. • So we must convert the voltage from AC to DC before feeding the electronic device. • Rectifiers give us this conversion.

  8. Half-wave Rectifier

  9. the diode is forward-biased during the positive half-cycle from 0 to  of the input voltage vin and so current flows through the diode and resistor where it develops an output voltage drop. vout = vin – vD • The diode is reverse-biased during the negative half-cycle from  to 2 so no current flows, and thus vout = 0 V

  10. Half-wave Rectifier signal

  11. Example • Design a DC voltmeter that will have a 10 v volt full-scale using a milli-ammeter with 1 milli-ampere full-scale and internal resistance 20 Ω , a junction diode, and an external resistor R whose value must be found. The input is an AC voltage with a value of 63 volts peak-to-peak. Assume that the diode is ideal.

  12. Soluation • Typically, a voltmeter is a modified milli-ammeter where an external resistor RV is connected in series with the milli-ammeter as shown in figure below.

  13. The diode begins conducting after the input voltage shown by the dotted curve rises to about 0.7 V

  14. The conduction begins at Δv = vin – vout corresponding to angle θ • The input waveform is a sinusoid of the form vin = Vp sinωt , ωt = θ • From equation Δv = vin – vout if vout = 0 then Vin = Δv and thus Δv = Vp sinθ θ = sin–1Δv ⁄ Vp

  15. We also observe that the conduction terminates at the angle (π – θ) and therefore the entire conduction angle is (π – θ) – θ = (π – 2θ)

  16. Generally, the angle θ is small and thus is small and thus cosθ ≈ 1 and (π – 2θ) ≈ π.

  17. V average • For ideal diode • For Silicon diode

  18. Example • For the half-wave rectifier circuit shown below, the Vr.m.sequal to 12v . Draw input and output and diode waveforms, and find the value of average for the load voltage and current.

  19. Soluation

  20. Referances • SCHUM’S OUTLINE OF THEORY AND PROBLEMS OF “ELECTRONIC DEVICES AND CIRCUITS” , By: JIMMIE J. CATHEY, Chapter 2. • “ELECTRONIC DEVICES AND CIRCUIT THEORY”, By ROBERT BOYLESTAD and LOUIS NASHELSKY

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