Questions

Consider figure 4 of Zener diode. Let \(R = 1 ~k\Omega\), \(V_Z = 10 ~V\), \(E = 14 ~V\) and \(R_L = 3 ~k\Omega\). Determine the state of the Zener diode.
Consider figure 6 of Zener diode. The zener diode has \(V_Z = 18 ~V\). The voltage across the load stays at \(18 ~V\) as long as the \(I_Z\) is maintained between \(200 ~mA\) and \(2 ~A\). Find the value of the series resistance R, So that \(E_0\) remains \(18 ~V\) and the input voltage varies between \(22 ~V\) to \(28 ~V\).
Consider figure 5 of Zener diode. Let \(R = 1 ~k\Omega\), \(V_Z = 10 ~V\), and \(E = 50 ~V\). Determine the range of \(R_L\) which results in voltage regulation across \(R_L\).
The circuit of uses two zener diodes, each rated at \(15 ~V\), \(200 ~mA\). If the circuit is connected to a 45-volt unregulated supply, determine : (i) The regulated output voltage and (ii) The value of series resistance \(R\)
What value of series resistance is required when three 10-watt, 10-volt, 1000 mA zener diodes are connected in series to obtain a 30-volt regulated output from a 45 volt d.c. power source ?
A power supply A delivers \(10 ~V_{dc}\) with a ripple of \(0.5 ~V_{r.m.s.}\) while the power supply \(B\) delivers \(25 ~V_{dc}\) with a ripple of \(1 ~mV_{r.m.s.}\) Which is better power supply ?
The bridge rectifier uses silicon diodes. Let input voltage is \(12 ~V\) ac and the load resistance is \(12 ~k\Omega\). Find (i) d.c. output (ii) d.c. output current. Use simplified model for the diodes.
A full-wave rectifier uses two diodes, the internal resistance of each diode may be assumed constant at \(20 ~\Omega.\) The transformer r.m.s. secondary voltage from centre tap to each end of secondary is \(50 ~V\) and load resistance is \(980 ~\Omega\). Find : (i) the mean load current (ii) the r.m.s. value of load current
An input ac voltage of \(115 ~V\) is fed into a stepdown transformer having a stepdown ratio of \(10:1\) which is then fed into a bridge rectifier. The out of the bridge rectifier is connected with a capacitor filter of capacitance of \(50 ~\mu F\) and a load resistance of \(2.2 ~k\Omega\). Find the output dc voltage.
The choke has a d.c. resistance of \(25 ~\Omega\). What is the d.c. voltage if the full-wave signal into the choke has a peak value of \(25.7 ~V\) ?

Answers

ON
\(R = 3.33 ~\Omega\)
\(R_{L\text{min}} = \frac{R V_Z}{(E_i - V_Z)} = 250 ~\Omega\) to \(R_{L\text{max}} = \frac{E_0}{I-I_{ZM}} = 1.25 ~k\Omega\)
\(30 ~V\) and \(R = \frac{E_i - E_0}{I_{ZM}} = 75 ~\Omega\)
\(R = \frac{E_i - E_0}{I_{ZM}} = 15 ~\Omega\)
\(\text{Ripple Factor } = \frac{V_{rms}}{V{dc}}.\) Hence, \(B\)
\(V_{dc} = 2\frac{\sqrt{2}V_rms}{\pi} = 9.91 ~V\), \(I_{av} = \frac{V_{dc}}{R_L}= 825.8 ~\mu A\)
\(I_{dc} = \frac{2}{\pi}\frac{\sqrt{2}V_{rms}}{r_d+R_L} = 45 ~mA\) and \(I_{rms} = \frac{I_m}{\sqrt{2}} = 50 ~mA\)
\(V_{dc} = V_m - V_d - I_m X_c\)
\(V_{dc} = \frac{V'_{dc}}{R + R_L} R_L \)