Physics 2420 In-Class Problems: Semiconductors & Diodes

1. A triangular wave is shown in the diagram below. It is purely AC and V_{peak- to-peak} = 20.0 Volts. The wave is used as the input for various rectifying circuits. Treat the diodes as ideal (V_B = 0).
   
   1. Sketch the output voltage for this wave for a half-wave rectifier. Determine V_DC.
      
   2. Sketch the output voltage for this wave for a centre-tapped full-wave rectifier where N_in:N_out is 5:2. Determine V_DC.
      
   3. Sketch the output voltage for this wave for a full-wave bridge rectifier where N_in:N_out is 1:3. Determine V_DC.
      
   

2. The diagram below shows a simple diode circuit with a battery. In this particular case, the diode is said to be forward-biased. Treat the diode as ideal (i.e. V_B = 0). Sketch the voltage drop over the resistor for
   
   1. V = 0 ,
   2. V = ½V_s ,
   3. V = V_s , and
   4. V = 2V_s.
   

3. The diagram below shows a reverse-biased diode circuit. Treat the diode as ideal. Sketch the voltage drop over the resistor for
   
   1. V = 0 ,
   2. V = V_s/4 ,
   3. V = ½V_s ,
   4. V = 3V_s/4 ,and
   5. V = V_s.
   

4. An ac signal V = 10.0sin(1500t) is feed through a N_in:N_out = 1:2 bridge rectifier and then through a capacitor input filter. The diodes in the rectifier are silicon (V_B = 0.7 V). The filter capacitor is C = 10 μF and the filter resistor is R = 2000 Ω.
   1. What is the peak voltage and frequency of the rectified wave?
   2. What is the ripple factor r, V_DC, V_r(peak), and V_{r (rms)}

5. Repeat Question 4 for an inductor input filter. The inductor is L = 0.010 mH and has a resistance R_W = 75 Ω.
   

Questions? mike.coombes@kwantlen.ca