Chapter - 4 : Analog Electronic Meters

Example 4.1 - Page No : 86

In [2]:
#Given data
V_CC= 12 # in volt
V_BE=0.7 #in volt
Rsm=4.3 #value o Rs+Rm in kohm
I=1 #in mA

# Part (i)
V= 5 #in volt
V_E= V-V_BE # in volt
Im= V_E/Rsm # in mA
I_E=Im # in mA
print "Meter Current = %0.f mA" %Im

# Part(ii)
h_FE= 100 
Im=Im*10**-3 #in amp
I_B= Im/h_FE # in amp
Rin= V/I_B # in ohm
print "Input resistance with transistor = %0.f kohm" %(Rin*10**-3)
# without transistor
Rin= Rsm 
print "Input resistance without transistor = %0.1f kohm" %Rin

# Part(iii)
V=2.5 # in volt
V_E= V-V_BE # in volt
Im= V_E/Rsm # in mA
I_E=Im # in mA
print "Meter current when the dc input voltage is 2.5 volt = %0.2f mA" %Im

Meter Current = 1 mA
Input resistance with transistor = 500 kohm
Input resistance without transistor = 4.3 kohm
Meter current when the dc input voltage is 2.5 volt = 0.42 mA

Example 4.2 - Page No : 87

In [4]:
 #Given data
V_CC= 12 # in volt
V_BE=0.7 #in volt
R_E1=3.3 # in kohm
V_EE= -12 # in volt
# Part (a) when V=0
V= 0 #in volt
V_E1= V-V_BE-V_EE # in volt
I_E1= V_E1/R_E1 # in mA
print "Emitter current when input voltage is zero volt = %0.1f mA" %I_E1

# Part(b)
# Part (i) when V=2 volt
V= 2 #in volt
V_P=0 
V_E1= V-V_BE # in volt
V_E2= V_P-V_BE # in volt
Vm= V_E1-V_E2 # in volt
print "Meter circuit voltage when input voltage is 2 volt = %0.f V" %Vm

# Part (ii) when V=1 volt
V= 1 #in volt
V_P=0 
V_E1= V-V_BE # in volt
V_E2= V_P-V_BE # in volt
Vm= V_E1-V_E2 # in volt
print "Meter circuit voltage when input voltage is 1 volt = %0.f V" %Vm

Emitter current when input voltage is zero volt = 3.4 mA
Meter circuit voltage when input voltage is 2 volt = 2 V
Meter circuit voltage when input voltage is 1 volt = 1 V

Example 4.4 - Page No : 92

In [5]:
 #Given data
Im= 200 # in micro A
Im=Im*10**-6 # in amp
Rm= 5 # in kohm
Rm=Rm*10**3 # in ohm
I_B= 0.5 # in micro amp
I_B=I_B*10**-6 # in amp
V=25 # in mV
V=V*10**-3 # in volt
Vout= Im*Rm # in volt
I= 500*I_B # in amp
R1= V/I # in ohm
print "The value of resistor = %0.f ohm" %R1
Rf= (Vout-V)/I # in ohm
print "Feedback resistor = %0.1f kohm" %(Rf*10**-3)

The value of resistor = 100 ohm
Feedback resistor = 3.9 kohm

Example 4.5 - Page No : 93

In [6]:
 #Given data
Im= 1 # in mA
Im=Im*10**-3 # in amp
Rm= 100 # in ohm
V=1.2 # in volt
R1= V/Im # in ohm
print "The value of resistance = %0.1f kohm" %(R1*10**-3)
Vout= Im*(Rm+R1) # in volt
print "Output voltage = %0.1f V" %Vout

The value of resistance = 1.2 kohm
Output voltage = 1.3 V

Example 4.6 - Page No : 100

In [8]:
from math import sqrt 
#Given data
Vrms=120 # in mV
Iav= 1.25 # in mA
I_max= 1/0.318*Iav # in mA
Vmax= sqrt(2)*Vrms # in mV
R2= Vmax/I_max # in ohm
print "Value of R2 = %0.1f ohm" %R2
# when input voltage is 60 volt
Vrms=60 # in mV
Vmax= sqrt(2)*Vrms # in mV
I_max= Vmax/R2 # in mA
Iav= I_max*0.318 # in mA
print "Average value of meter current = %0.3f mA" %Iav

Value of R2 = 43.2 ohm
Average value of meter current = 0.625 mA