# Chapter 20 , Regulated Power Supplies¶

## Example 20.1 , Page Number 466¶

In [1]:
import math

#Variables

dVL = 100.0 * 10**-6                 #Change in output voltage (in volts)
dVin = 5.0                           #Change in input voltage (in volts)

#Calculation

LR = dVL / dVin                      #Line regulation (in volt per volt)

#Result

print "The value of line regulation is ",LR * 10**6," micro-volt/volt."

The value of line regulation is  20.0  micro-volt/volt.


## Example 20.2 , Page Number 466¶

In [2]:
import math

#Variables

LR = 1.4                       #Line regulation (in micro-volt per volt)
dVS = 10                       #Change in source voltage (in volts)

#Calculation

dVL = LR * dVS                 #Change in output voltage (in micro-volts)

#Result

print "The change in output voltage is ",dVL," micro-volt."

The change in output voltage is  14.0  micro-volt.


## Example 20.3 , Page Number 466¶

In [3]:
import math

#Variables

dIL = 40.0                    #Change in current (in milli-Ampere)
VNL = 8.0                     #Voltage under no load (in volts)
VFL = 7.995                   #Voltage under full load (in volts)

#Calculation

LR = (VNL - VFL)/ dIL         #Line regulation (in milli-volt per milli-Ampere)

#Result

print "Line regulation is ",LR * 10**3,"mV/mA."

Line regulation is  0.125 mV/mA.


## Example 20.4 , Page Number 467¶

In [4]:
import math

#Variables

LR = 10.0                              #Load regulation (in micro-volt per milli-Ampere)
VNL = 5.0                              #No load Voltage (in volts)
dIL = 20.0                             #Change in current (in milli-Ampere)

#Calculation

VFL = VNL - LR * dIL * 10**-6          #Full load Voltage (in volts)

#Result

print "Full load Voltage is ",VFL," V."

Full load Voltage is  4.9998  V.


## Example 20.5 , Page Number 467¶

In [5]:
import math

#Variables

V0 = 10                      #Regulated dc supply (in volts)
LR = 0.00002                 #Line regulation

#Calculation

dV = LR * V0                 #Change in output voltage (in volts)

#Result

print "Change in output voltage is ",dV * 10**3," mV."

Change in output voltage is  0.2  mV.


## Example 20.6 , Page Number 468¶

In [6]:
import math

#Variables

VS = 30.0                   #Source voltage (in volts)
RS = 240.0                  #Series resistance (in ohm)
Vz = 12.0                   #Zener voltage (in volts)
RL = 500.0                  #Load resistance (in ohm)

#Calculation

VL = Vz                     #Voltage drop across load (in volts)
IS = (VS - Vz) / RS         #Current through RS (in Ampere)
VRS = IS * RS               #Voltage drop across series resistance (in volts)
IL = VL / RL                #Load current (in Ampere)
IZ = IS - IL                #Zener current (in Ampere)

#Result

print "Load voltage is ",VL," V.\nVoltage drop across series resistance is ",VRS," V.\nCurrent through Zener diode is ",IZ," A."

Load voltage is  12.0  V.
Voltage drop across series resistance is  18.0  V.
Current through Zener diode is  0.051  A.


## Example 20.7 , Page Number 470¶

In [7]:
import math

#Variables

VZ = 5.1                      #Voltage across zener diode (in volts)
rZ = 10                       #Zener diode resistance (in ohm)
IZmin = 1 * 10**-3            #Minimum zener diode current (in Ampere)
IZmax = 15 * 10**-3           #Maximum zener diode current (in Ampere)
RS = 600                      #Serier resistance (in ohm)

#Calculation

VOmin = VZ + IZmin * rZ       #Minimum value of output voltage (in volts)
VSmin = IZmin * RS + VOmin    #Minimum value of input voltage (in volts)
VOmax = VZ + IZmax * rZ       #Maximum value of output voltage (in volts)
VSmax = IZmax * RS + VOmax    #Maximum value of input voltage (in volts)

#Result

print "Minimum value of input voltage is ",VSmin," V.\nMaximum value of input voltage is ",VSmax," V."

Minimum value of input voltage is  5.71  V.
Maximum value of input voltage is  14.25  V.


## Example 20.8 , Page Number 470¶

In [8]:
import math

#Variables

VS = 24.0                        #Source voltage (in volts)
RS = 500.0                       #Series resistance (in ohm)
VZ = 12.0                        #Zener Voltage (in volts)
IZmin = 3.0                      #Minimum Zener current (in milli-Ampere)
IZmax = 90.0                     #Maximum Zener current (in milli-Ampere)
rZ = 0.0                         #Zener resistance (in ohm)

#Calculation

IS = (VS - VZ) / RS              #Current through RS (in Ampere)
ILmax = IS - IZmin * 10**-3      #Maximum value of load Current (in Ampere)
RLmin = VZ / ILmax               #Minimum value of Load resistance (in ohm)

#Result

print "Minimum value of load resistance is ",round(RLmin)," ohm."

Minimum value of load resistance is  571.0  ohm.


## Example 20.9 , Page Number 471¶

In [9]:
import math

#Variables

VZ = 10.0                                   #Zener voltage (in volts)
RS = 1.0                                    #Series Resistance (in kilo-ohm)
RL = 2.0                                    #Load Resistance (in kilo-ohm)
VSmin = 22.0                                #Minimum source voltage (in volts)
VSmax = 40                                  #Maximum source voltage (in volts)

#Calculation

IL = VZ / RL                                #Load current (in milli-Ampere)
IZmax = (VSmax - VZ) / RS - IL              #Maximum value of zener current (in milli-Ampere)
IZmin = (VSmin - VZ) / RS - IL              #Minimum value of zener current (in milli-Ampere)

#Result

print "Maximum value of zener current is ",IZmax," mA.\nMinimum value of zener current is ",IZmin," mA."

Maximum value of zener current is  25.0  mA.
Minimum value of zener current is  7.0  mA.


## Example 20.10 , Page Number 472¶

In [10]:
import math

#Variables

VZ = 10.0                                #Zener voltage (in volts)
VSmin = 13.0                             #Minimum source voltage (in volts)
VSmax = 16.0                             #Maximum source voltage (in volts)
ILmin = 10.0                             #Minimum load current (in milli-Ampere)
ILmax = 85.0                             #Maximum load current (in milli-Ampere)
IZmin = 15.0                             #Minimum zener current (in milli-Ampere)

#Calculation

RSmax = (VSmin - VZ)/ (IZmin + ILmax)    #Maximum value of RS (in kilo-ohm)
IZmax = (VSmax - VZ)/ RSmax - ILmin      #Maximum zener current (in milli-Ampere)
PZmax = IZmax * 10**-3 * VZ              #Maximum power dissipation in zener (in watt)

#Result

print "Maximum value of RS is ",RSmax * 10**3," ohm.\nMaximum power dissipation be the zener diode is ",PZmax," W."

Maximum value of RS is  30.0  ohm.
Maximum power dissipation be the zener diode is  1.9  W.


## Example 20.11 , Page Number 473¶

In [11]:
import math

#Variables

VSmin = 19.5                            #Minimum source voltage (in volts)
VSmax = 22.5                            #Maximum source voltage (in volts)
RL = 6.0 * 10**3                        #Load resistance (in ohm)
VZ = 18.0                               #Zener voltage (in volts)
IZmin = 2.0 * 10**-6                    #Minimum zener current (in Ampere)
PZmax = 60.0 * 10**-3                   #Maximum power dissipation (in watt)
rZ = 20.0                               #Zener resistance (in ohm)
VL = VZ                                 #Voltage across load resistance (in volt)

#Calculation

IZmax = (PZmax / rZ)**0.5                #Maximum value of zener current (in milli-Ampere)
IL = VL / RL                             #Load current (in milli-Ampere)
RSmax = (VSmin - VZ) / (IZmin + IL)      #Maximum value of regulating resistance (in kilo-ohm)
RSmin = (VSmax - VZ) / (IZmax + IL)      #Minimum value of regulating resistance (in kilo-ohm)

#Result

print "Magnitude of regulating resistance should be between ",round(RSmin,1)," ohm and ",round(RSmax)," ohm."

Magnitude of regulating resistance should be between  77.9  ohm and  500.0  ohm.


## Example 20.12 , Page Number 473¶

In [12]:
import math

#Variables

VSmin = 8.0                    #Minimum source voltage (in volts)
VSmax = 12                     #Maximum source voltage (in volts)
RS = 2.2                       #Resistance (in kilo-ohm)
VZ = 5.0                       #Zener voltage (in volts)
RL = 10.0                      #Load resistance (in kilo-ohm)
VL = VZ                        #Voltage across load (in volts)

#Calculation

ISmin = (VSmin - VZ)/ RS       #Minimum value of input current (in milli-Ampere)
ISmax = (VSmax - VZ)/RS        #Maximum value of input current (in milli-Ampere)
IL = VL / RL                   #Load current (in milli-Ampere)
IZmin = ISmin - IL             #Minimum Zener current (in milli-Ampere)
IZmax = ISmax - IL             #Maximum Zener current (in milli-Ampere)

#Result

print "Minimum value of Zener current is ",round(IZmin,3)," mA.\nMaximum value of Zener current is ",round(IZmax,3)," mA."

Minimum value of Zener current is  0.864  mA.
Maximum value of Zener current is  2.682  mA.


## Example 20.13 , Page Number 474¶

In [13]:
import math

#Variables

VO = VL = 5.0                     #Output voltage (in volts)
IL = 20.0                         #Load current (in milli-Ampere)
PZmax = 500.0                     #Maximum power dissipation in zener (in milli-watt)
VSmin = 9.0                       #Minimum source voltage (in volts)
VSmax = 15.0                      #Maximum source voltage (in volts)

#Calculation

IZmax = PZmax / VZ                #Maximum zener current (in milli-Ampere)
ISmax = IL + IZ                   #Maximum input current (in milli-Ampere)
RSmin = (VSmax - VZ)/(IZmax + IL) #Minimum value of regulating resistance (in kilo-ohm)
IZ = (VSmin - VZ)/ RSmin - IL     #Minimum value of zener current

#Result

print "Input varies from the normal 12 v within the range of +- 3 V."
print "Zener current vary from ",IZ," mA to ",IZmax," mA."
print "For safety purpose RS should be 220 ohm."

Input varies from the normal 12 v within the range of +- 3 V.
Zener current vary from  28.0  mA to  100.0  mA.
For safety purpose RS should be 220 ohm.


## Example 20.14 , Page Number 475¶

In [14]:
import math

#Variables

RS = 500.0                                    #Series resistance (in ohm)
RL = 1.0                                      #Load resistance (in kilo-ohm)
VZ = 10.0                                     #Zener voltage (in volts)
IZmin = 5.0                                   #Minimum Zener current (in milli-Ampere)
IZmax = 55.0                                  #Maximum Zener current (in milli-Ampere)

#Calculation

IL = VZ / RL                                  #Load current (in milli-Ampere)
VSmin = (IL + IZmin) * RS * 10**-3 + VZ       #Minimum value of input voltage (in volts)
VSmax = (IL + IZmax) * RS * 10**-3 + VZ       #Maximum value of input voltage (in volts)

#Result

print "The minimum value of voltage level at input is ",VSmin," V and the maximum is ",VSmax," V."

The minimum value of voltage level at input is  17.5  V and the maximum is  42.5  V.


## Example 20.15 , Page Number 476¶

In [15]:
import math

#Variables

VS = 15.0                   #Input voltage (in volts)
RS = 33.0                   #Series resistance (in ohm)
beta = 100.0                #common-emitter current gain
RL = 100.0                  #Load resistance (in ohm)
VZ = 10.0                   #Voltage across zener diode (in volts)
VBE = 0.7                   #Voltage across base and emitter

#Calculation

VL = VZ + VBE               #Load voltage (in volts)
IL = VL / RL                #Load current (in Ampere)
IS = (VS - VL) / RS         #Current through RS (in Ampere)
IC = IS - IL                #Collector current (in Ampere)
IB = IZ = IC/beta           #Base current (in Ampere)

#Result

print "Load voltage is ",VL," V."
print "Load current is ",IL * 10**3," mA."
print "Current  through Rs is ",round(IS * 10**3,1)," mA."
print "Collector current is ",round(IC* 10**3,1)," mA."
print "Base current is ",round(IB * 10**6)," micro-A."

Load voltage is  10.7  V.
Current  through Rs is  130.3  mA.
Collector current is  23.3  mA.
Base current is  233.0  micro-A.


## Example 20.16 , Page Number 478¶

In [16]:
import math

#Variables

VS = 15.0                      #Input voltage (in volts)
VZ = 8.3                       #Zener voltage (in volts)
beta = 100.0                   #Common-emitter current gain
R = 1.8                        #Resistance (in kilo-ohm)
RL = 2.0                       #Resistance (in kilo-ohm)
VBE = 0.7                      #Voltage across base-emitter junction (in volts)

#Calculation

VL = VZ - VBE                  #Voltage across load (in volts)
VCE = VS - VL                  #Collector to emitter voltage (in volts)
IR = (VS - VZ)/ R              #Current through R (in milli-Ampere)
IL = VL / RL                   #Load current (in milli-Ampere)
IB = IL / beta                 #Base current (in milli-Ampere)
IZ = IR - IB                   #Current through Zener (in milli-Ampere)

#Result

print "Load voltage is ",VL," V."
print "Collector to Emitter voltage is ",VCE," V."
print "Current through R is ",round(IR,2)," mA."
print "Load current is ",IL," mA."
print "Base current is ",IB * 10**3," micro-A."
print "Current through Zener is ",round(IZ,2)," mA."

#Calculation error in book in the value of beta and in IB and IZ.

Load voltage is  7.6  V.
Collector to Emitter voltage is  7.4  V.
Current through R is  3.72  mA.
Base current is  38.0  micro-A.
Current through Zener is  3.68  mA.


## Example 20.17 , Page Number 479¶

In [17]:
import math

#Variables

IZmin = 0                     #Minimun Zener current (in Ampere)
ILmax = 2.0                   #Maximum load current (in Ampere)
VL = 12.0                     #Voltage across load (in volts)
VSmin = 15.0                  #Minimum Input voltage (in volts)
VSmax = 20.0                  #Maximum Input Voltage (in volts)
beta = 100                    #common emitter current gain
VBE = 0.5                     #Voltage between base-emitter junction (in volts)
VZ = 12.5                     #Voltage across zener diode (in volts)
IZmin = 1.0 * 10**-3          #Current through Zener diode
ICmax = ILmax                 #Maximum Collector current (in Ampere)

#Calculation

IBmax = ICmax / beta          #Maximum collector current
IR = IBmax + IZmin            #Current through resistance R (in Ampere)
Rmax = (VSmin - VZ)/ IR       #Maximum value of resistance R (in ohm)
IZmax = (VSmax - VZ)/ Rmax    #Maximum value of Zener current (in Ampere)
PZmax = VZ * IZmax            #Maximum power dissipation in Zener Diode (in watt)
PRmax = (VSmax - VZ) * IZmax  #Maximum power dissipated in Resistance R (in watt)
VCEmax = VSmax - VL           #Maximum value of collector-to-emitter voltage (in volts)
PDmax = VCEmax * ILmax        #Maximum power dissipation of the transistor (in watt)

#Result

print "Maximum value of R is ",round(Rmax)," ohm.\nMaximum power dissipation of the zener diode is ",round(PZmax,2)," W.\nMaximum power dissipation of resistance R is ",round(PRmax,2)," W.\nMaximum power dissipation of the transistor is ",PDmax," W."

#Correction to be done in the formula used for IZmax in the book.Correct approach is used in the solved example here.

Maximum value of R is  119.0  ohm.
Maximum power dissipation of the zener diode is  0.79  W.
Maximum power dissipation of resistance R is  0.47  W.
Maximum power dissipation of the transistor is  16.0  W.


## Example 20.18 , Page Number 481¶

In [18]:
import math

#Variables

VL = 12.0                      #Voltage across load (in volts)
IL = 200.0                     #Load current (in milli-Ampere)
VS = 30.0                      #Source voltage (in volts)
RS = 10.0                      #Series resistance (in ohm)
beta1 = hfe1 = 150.0           #common-emitter current gain 1
beta2 = hfe2 = 100.0           #common-emitter current gain 2
IC1 = 10.0                     #Collector current (in milli-Ampere)
VBE1 = 0.7                     #Emitter-to-Base voltage1 (in volts)
VBE2 = 0.7                     #Emitter-to-Base voltage2 (in volts)
VZ = VR = 6.0                  #Voltage across zener diode (in volts)
RZ = 10.0                      #Resistance of zener diode (in ohm)
IZ = 20.0                      #Current through zener diode (in milli-Ampere)
ID = 10.0 * 10**-3             #Current (in Ampere)
I1 = 10.0 * 10**-3             #Current (in Ampere)

#Calculation

RD = (VL - VZ) / ID            #Resistance (in ohm)
V2 = VZ + VBE2                 #Voltage (in volts)
R1 = (VL - V2)/I1              #Value of resistance R1 (in ohm)
R2 = R1 * (V2 / (VL - V2))     #Value of resistance R2 (in ohm)
IB1 = (IL + I1 + ID) / beta1   #Base Current IB1 (in Ampere)
I = IB1 + IC1                  #Current through resistance R3 (in Ampere)
R3 = (VS - (VBE1 + VL))/I      #Value of resistance (in ohm)

#Result

print "Value of Resistance RD is ",RD," ohm.\nValue of Resistance R1 and R2 is ",R1," ohm and ",R2," ohm."
print "Value of Resistance R3 is ",round(R3,1)," kilo-ohm."

#Error in the formula used for R1 in book. Correct formula is used here.

Value of Resistance RD is  600.0  ohm.
Value of Resistance R1 and R2 is  530.0  ohm and  670.0  ohm.
Value of Resistance R3 is  1.5  kilo-ohm.


## Example 20.19 , Page Number 484¶

In [19]:
import math

#Variables

VS = 25.0                  #Source voltage (in volts)
VZ = 15.0                  #Zener voltage (in volts)
RL = 1.0                   #Load resistance (in kilo-ohm)
VBE = 0.7                  #Emitter-to-Base voltage (in volts)

#Calculation

Vout = VZ/2 + VBE          #Output voltage (in volts)
IL = Vout / RL             #Load current (in milli-Ampere)
IE1 = IL                   #Current (in milli-Ampere)
VCE1 = VS - Vout           #Collector-To-Emitter voltage (in volts)
P1 = VCE1 * IE1            #Power dissipated (in watt)

#Result

print "Vout is ",Vout," V.\nIL is ",IL," mA.\nIE1 is ",IE1," mA.\nP1 is ",P1," W."

#Calculation error in book for the value of P1.

Vout is  8.2  V.
IL is  8.2  mA.
IE1 is  8.2  mA.
P1 is  137.76  W.


## Example 20.20 , Page Number 492¶

In [20]:
import math

#Variables

IADJ = 100.0 * 10**-6                            #Current (in Ampere)
Vin = 35.0                                       #Input voltage (in volts)
R1 = 220.0                                       #Resistance1 (in ohm)
R2min = 0                                        #Resistance2 minimum (in ohm)
R2max = 5.0 * 10**3                              #Resistance2 maximum (in ohm)
VREF = 1.25                                      #Reference voltage (in volts)

#Calculation

Voutmin = VREF * (R2min/R1 + 1) + IADJ * R2min   #Minimum output voltage (in volts)
Voutmax = VREF * (R2max/R1 + 1) + IADJ * R2max   #Maximum output voltage (in volts)

#Result

print "Maximum output voltage is ",round(Voutmax,2)," V.\nMinimum output voltage is ",Voutmin," V."

Maximum output voltage is  30.16  V.
Minimum output voltage is  1.25  V.


## Example 20.21 , Page Number 492¶

In [21]:
import math

#Variables

R1 = 220.0               #Resistance1 (in ohm)
R2 = 1.5 * 10**3         #Resistance2 (in ohm)
VREF = 1.25              #Reference voltage (in volts)

#Calculation

Vo = VREF * (R2/R1 + 1)  #Regulated dc output voltage (in volts)

#Result

print "Regulated dc output voltage is ",round(Vo,2)," V."

#Calculation error in the book.

Regulated dc output voltage is  9.77  V.


## Example 20.22 , Page Number 493¶

In [22]:
import math

#Variables

R1 = 240.0               #Resistance1 (in ohm)
R2 = 2.4 * 10**3         #Resistance2 (in ohm)
VREF = 1.25              #Reference voltage (in volts)

#Calculation

Vo = VREF * (R2/R1 + 1)  #Regulated dc output voltage (in volts)

#Result

print "Regulated dc output voltage is ",Vo," V."

Regulated dc output voltage is  13.75  V.