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Question on Electrical and Electronics Engineering
Design a half-wave rectifier without any smoothing capacitor. The supply voltage to the Germanium diode is 7.07 Volts RMS at a frequency of 50 Hz. The load resistance is 100 z. Calculate the given process. - DC voltage. - Ripple voltage (peak-to-peak). - Ripple percentage. - Current drawn from the transformer. - Line regulation percentage.

Answers

Answered by kvnmurty
0
see the diagram.

R = 100 Ω         f= 50Hz  and  ω = 100π  rad/sec
Vi peak = 7.07 V rms * √2 = 10 V
Vi = 10 Sin (100π t)  Volts
Assume a voltage drop of 0.7 V across the Germanium diode.
Time period = 1/50 = 20 ms
Ripple voltage = peak-to-peak = 10 - 0.7 = 9.3 Volts
DC voltage = average of the voltage signal over a time period:
=
Vi\ \textgreater \ =0.7V\ for\ Sin^{-1} 0.07 \le \omega t \le \pi-Sin^{-1} 0.07\\\\i.e.,for\  0.223ms \le t \le 9.777 ms\\\\V_{avg}=\frac{1}{T}\int \limits_{0}^{T} {V_o} \, dt\\\\=\frac{1}{0.020} \int \limits_{0.000223}^{0.009777} [10 Sin(100\pi t)-0.7]\ dt\\\\=\frac{1}{0.020}[-\frac{10}{100 \pi}\ cos(100\pi t)-0.7\ t ]_{0.000223}^{0.009777}\\\\=\frac{1}{0.020}[\frac{1}{10\pi}(cos(0.0223\pi)-cos(0.9777\pi)) -0.7(0.009777-0.000223)] \\\\=50[0.0568 ]=2.84 Volts

If we neglect the voltage drop across the diode, then the average voltage
  = 10 V / 
π = 3.18 V

The current from the transformer 
I(t) = [10 Sin (100 π t) - 0.7 ] /100     during   0.223 ms <= t <= 9.777 ms
      = 0  during the rest of the time period from 0 to 20 ms 

Average current drawn from the transformer = 2.84/100 = 28.4 mA
Average current if we neglect the voltage drop across the diode:  31.8 mA

Line regulation% = (change in Vo / Change in Vi)  * 100
       = (9.3 - 0.7)*100 /(10 - (-10)) = 860/20 = 43%

If we neglect the drop across the diode then, line regulation = 10*100/20 = 50%

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