# Chapter 6: Vaccum Tubes¶

### Example 6.1 Page no.195¶

In [3]:
#Given
from pylab import *
#Given Circuit Data
V=[0,0.5,1,1.5,2]                      #V, voltage
I=[0,1.6,4,6.7,9.4]                     #mA, current

#Calculation
dVp=0.5                                   #V, change in plate voltage
dIp=2.7*10**(-3)                      #A, change in plate current
rp=dVp/dIp                              # Dynamic Plate Resistance

#Result
print "The Dynamic Plate Resistance is rp=   ",rp,"ohm"

#plot

a=plot(V,I)
xlabel("V")
ylabel("I (mA)")

show(a)

The Dynamic Plate Resistance is rp=    185.185185185 ohm


### Example 6.2 Page no.202¶

In [30]:
from math import *
from pylab import *
#Calculation
dip=(14.0-10.7)*10**(-3)         #A
dvp=20                                   #V
rp=dvp/dip
diP=(12.4-5.3)*10**(-3)          #A
dvG=1                                    #V
gm=diP/dvG
u=gm*rp
ut=(192-150)/1

# Result
print " The Plate AC Resistance is rp=  ",round(rp/10**(3),2),"kohm"
print " The Mutual Conductance is gm=  ",gm/10**(-3),"mS"
print " The Graphical Amplification Factor is u= ",round(u,2)
print " The Theoretical Amplification Factor is ut= ",ut

#plot
#At Vg=0
V1=[0,50,100,150]
I1=[0,3.5,11.2,20.0]

#at Vg=-1
V2=[60,100,150,200]
I2=[0,4,12.4,21.5]

#at Vg=-2
V3=[100,150,200]
I3=[0,5.4,14.1]

#at Vg=-3
V4=[160,200,250]
I4=[0,3.4,12.4]

#at Vg=-4
V5=[220,250,300]
I5=[0,2.5,11.3]

figure(1)
import numpy
import pylab
fig = plt.figure()

a1=plot(V1,I1)
a2=plot(V2,I2)
a3=plot(V3,I3)
a4=plot(V4,I3)
a5=plot(V5,I4)
xlabel("Vp (V)")
ylabel("Ip(mA)")
ax.annotate('vg=0', xy=(152,21),
arrowprops=dict(facecolor='black', shrink=0.5),
)
ax.annotate('vg=-1', xy=(200,21.5),
arrowprops=dict(facecolor='black', shrink=0.5),
)
ax.annotate('vg=-2', xy=(200,14.1),
arrowprops=dict(facecolor='black', shrink=0.5),
)
ax.annotate('vg=-3', xy=(250,12.4),
arrowprops=dict(facecolor='black', shrink=0.5),
)
ax.annotate('vg=-4',xy=(300,11.3),
arrowprops=dict(facecolor='black', shrink=0.5),
)
show(a1)
show(a2)
show(a3)
show(a4)
show(a5)

 The Plate AC Resistance is rp=   6.06 kohm
The Mutual Conductance is gm=   7.1 mS
The Graphical Amplification Factor is u=  43.03
The Theoretical Amplification Factor is ut=  42