# Chapter 3 - Multivibrator and Blocking Oscillators¶

## Example 3.1 : Page No. 3-101¶

In [5]:
# given data
R1=1.5 #in kohm
RF=15 #in kohm
A=2*10**5 #unitless
Ri=1 #in Mohm
Ro=75 #in ohm
fo=5 #in Hz
AF=1+RF/R1 #unitless
B=1/AF #unitless
RiF=(1+A*B)*Ri*10**6 #in ohm
RoF=Ro/(1+A*B) #in ohm
fF=fo*(1+A*B) #in ohm
print "Close loop voltage gain AF  = %0.2f " %AF
print "Value of RiF = %0.2e ohm"%RiF
print "Value of RoF = %0.2e ohm"%RoF
print "Value of fF = %0.f kHz"%(fF/1000)

Close loop voltage gain AF  = 11.00
Value of RiF = 1.82e+10 ohm
Value of RoF = 4.12e-03 ohm
Value of fF = 91 kHz


## Example 3.2 : Page No. 3-101¶

In [7]:
from __future__ import division
# given data
AF=100 #unitless
A=2*10**5 #unitless
Ri=1 #in Mohm
Ro=75 #in ohm
#let R1 =1 ohm
R1=1 #in ohm
#formula : AF=1+RF/R1
RF=(AF-1)*R1 #in kohm
B=1/AF #unitless
RiF=(1+A*B)*Ri*10**6 #in ohm
RoF=Ro/(1+A*B) #in ohm
print "Value of RF = %0.2f kohm"%RF
print "Value of RiF = %0.2e ohm"%RiF
print "Value of RoF = %0.2e ohm"%RoF

Value of RiF = 99.00 kohm
Value of RiF = 2.00e+09 ohm
Value of RoF = 3.75e-02 ohm


## Example 3.3 : Page No. 3-102¶

In [8]:
# given data
AF=1 #unitless
B=1 #unitless
A=2*10**5 #unitless
fo=5 #in Hz
Ri=1 #in Mohm
Ro=75 #in ohm
#let 1+AB=A  as A>>>1
RiF=A*Ri*10**6 #in ohm
RoF=Ro/A #in ohm
fF=fo*A #in ohm
print "Value of RiF = %0.2e ohm"%RiF
print "Value of RoF = %0.2e ohm"%RoF
print "Value of fF = %0.2f MHz"%(fF/10**6)

Value of RiF = 2.00e+11 ohm
Value of RoF = 3.75e-04 ohm
Value of fF = 1.00 MHz


## Example 3.4 : Page No. 3-103¶

In [13]:
 # given data
R1=50 #in Kohm
AF=-6 #unitless
# here AF=-RF/R1
RF=-AF*R1 #in kohm
print "Value of RF = %0.f kohm" %RF

Value of RF = 300 kohm


## Example 3.5 : Page No. 3-103¶

In [18]:
from __future__ import division
# given data
A=2*10**5 #unitless
Ri=1 #in Mohm
Ro=75 #in ohm
fo=5 #in Hz
R1=50 #in kohm
RF=300 #in kohm
K=RF/(R1+RF) #unitless
B=R1/(R1+RF) #unitless
AF=-(A*K/(1+A*B)) #unitless
RiF=R1 #in kohm   ideal
RoF=Ro/(1+A*B) #in ohm
fF=-(A*K*fo/AF) #in Hz
print "Close loop voltage gain AF = %0.2f"%AF
print "Value of RiF = %0.2f kohm"%RiF
print "Value of RoF = %0.2e ohm"%RoF
print "Value of fF = %0.f kHz"%(fF/1000)

Close loop voltage gain AF = -6.00
Value of RiF = 50.00 kohm
Value of RoF = 2.62e-03 ohm
Value of fF = 143 kHz


## Example 3.6 : Page No. 3-104¶

In [19]:
# given data
# let R1=R2=R3=R=10kohm
R=10 #in kohm
R1=R #in kohm
R2=R #in kohm
R3=R #in kohm
RF=3*R #in Kohm
print "Value of RF = %0.0f kohm"%RF

Value of RF = 30 kohm


## Example 3.7 : Page No. 3-104¶

In [20]:
 # given data
RF=1 #in Mohm
AV=-30 #unitless
#AV=-RF/R1=Vo/V1
R1=-RF*10**6/AV #in ohm
#for an inverting amplifier RiF=R1
RiF=R1 #in ohm
print "Value of R1 = %0.2f kohm"%(R1/1000)
print "Value of RiF = %0.2f kohm"%(RiF/1000)

Value of R1 = 33.33 kohm
Value of RiF = 33.33 kohm


## Example 3.8 : Page No. 3-105¶

In [21]:
 # given data
AV=-8 #unitless
Vin=-1 #in Volts
Imax=15 #in uA
Vo=AV*Vin #in Volts
#Formula : Vo=Imax*R2min
R2min=Vo/(Imax*10**-6) #in kohm
R1min=-Vin/(Imax*10**-6) #in kohm
print "Required value of R2 = %0.2f kohm"%(R2min/1000)
print "Required value of R1 = %0.2f kohm"%(R1min/1000)

Required value of R2 = 533.33 kohm
Required value of R1 = 66.67 kohm


## Example 3.9 : Page No. 3-106¶

In [22]:
 # given data
Vo=1.5 #in Volts
Vin=10 #in mVolts
RiF=500 #in kohm
R1=500 #in kohm
AF=Vo/(Vin*10**-3) #unitless
RF=AF*R1 #in Kohm
print "The value of RF = %0.2f Mohm"%(RF/1000)
#AF=-R2/R1*(1+R3/R2+R3/R4)
#Microphone resistance is Rm=1.2 Kohm
R1eff=100 #in Kohm
Rm=1.2 #in Kohm
R1=R1eff-Rm
R3=5*R1
R2=R3 #in Kohm
R4=R3/28 #in Kohm
print "Value of R1 = %0.2f kohm" %R1
print "Value of R2 = %0.2f kohm" %R2
print "Value of R3 = %0.2f kohm" %R3
print "Value of R4 = %0.2f kohm" %R4

The value of RF = 75.00 Mohm
Value of R1 = 98.80 kohm
Value of R2 = 494.00 kohm
Value of R3 = 494.00 kohm
Value of R4 = 17.64 kohm