Chapter 13: Integrated circuit Timers

Example 13.1 Page No 371

In [5]:
#Given
#From fig 13.7 (a)
Ra=6.8          #kohm, resistance
Rb=3.3          #Kohm
C=0.1           #microF, capacitance

#Calculation
thigh=0.695*(Ra+Rb)*C
tlow=0.695*Rb*C
f=1.44/((Ra+2*Rb)*C)

#Result
print"The value of high time is",round(thigh,1),"ms"
print"The value of low time is",round(tlow,2),"ms"
print"The value of frequency is",round(f,2),"khz"

The value of high time is 0.7 ms
The value of low time is 0.23 ms
The value of frequency is 1.07 ms

Example 13.2 Page No 373

In [7]:
#Given
#From fig 13.7 (a)
Ra=6.8          #kohm, resistance
Rb=3.3          #Kohm

#Calculation
D=Rb/(Ra+2*Rb)

#Result
print"The Duty Cycle is",round(D,2)

The Duty Cycle is 0.25

Example 13.3 Page No 377

In [2]:
#GIven
V=5             #V, Voltage
E1=0             #V
E2=1
Re=3            #Kohm, resistance (fig 13-10)
C=1             #microF

#Calculation
I=(V-E1)/(3.0)  #Current
fc=3/(Re*C)
df=0.2*fc*E2
fout=fc+df
E3=-1          #V
df_=0.2*fc*E3
fout_=fc+df_
Elower=-4
Eupper=4

#Result
print"(a)The charge current is",round(I,2),"mA"
print"(b)The current frequency is",fc,"KHz"
print"(c)df=",df*1000,"Hz","\nand The frequency shift is",(df-df_)*1000,"Hz"
print"fout was initially",fout*1000,"Hz . then changes to",fout_*1000,"Hz"
print"(d)The positive nd negative limits are",Eupper,"V and",Elower,"V"

(a)The charge current is 1.67 mA
(b)The current frequency is 1 KHz
(c)df= 200.0 Hz 
and The frequency shift is 400.0 Hz
fout was initially 1200.0 Hz . then changes to 800.0 Hz
(d)The positive nd negative limits are 4 V and -4 V

Example 13.4 Page No 380

In [19]:
#GIven
Ra=9.1       #Kohm
thigh=1      #ms

#Calculation
C=thigh*10**-3/(1.1*Ra)

#Result
print"The value of C is",round(C*10**3,1),"microF"

The value of C is 0.1 microF

Example 13.5 Page No 381

In [22]:
#Given
Ra=10              #Kohm
C=0.2              #microF
Ci=0.001           #microF

#calculation
thigh=1.1*(Ra*10**3*C*10**-6)
t=Ra*10**3*Ci

#Result
print"(a)The value of high time is",thigh*1000,"ms"
print"(b)Time constant is",t/1000,"ms"

(a)The value of high time is 2.2 ms
(b)Time constant is 0.01 ms

Example 13.6 Page No 383

In [24]:
#Given
Ra=10           #Kohm
C=0.1           #microF
f=1             #kHz

#Calculation
thigh=1.1*(Ra*10**3*C*10**-6)
#thigh should exceed two periods and be less than 3 periods.
thigh_=2.2      #ms, chose a value
Ra=thigh_/(1.1*C*10**-6)

#Result
print"(a) The time interval is",thigh*1000,"ms"
print"Ra is",Ra/10**6,"Kohm"

(a) The time interval is 1.1 ms
Ra is 20.0 Kohm

Example 13.7 Page No 387

In [26]:
#Given
R=100           #Kohm
C=0.01          #microF
p1=3           #pin
p2=4
p3=7
p4=8


#Calculation
T=R*10**3*C*10**-6
tlow1=4*T         #Using Table 13-2, pin=3 , time= 4*T
tlow2=8*T
tlow3=64*T
tlow4=128*T

#Result
print"(a)The required time is",tlow1*1000,"ms"
print"(b)The required time is",tlow2*1000,"ms"
print"(c)The required time is",tlow3*1000,"ms"
print"(d)The required time is",tlow4*1000,"ms"

(a)The required time is 4.0 ms
(b)The required time is 8.0 ms
(c)The required time is 64.0 ms
(d)The required time is 128.0 ms

Example 13.8 Page No 389

In [27]:
#Given
T=1          #s

#Calculation
#Pins 3,6,7 are jumpered
Tsum1=8*T+16*T
Tsum2=4*T+32*T+64*T


#Result
print"(a)The timing cycle is",Tsum1,"s"
print"(b)The timing cycle is",Tsum2,"s"

(a)The timing cycle is 24 s
(b)The timing cycle is 100 s

Example 13.9 Page No 389

In [34]:
#Given
C=1        #microF
R=5        #Mohm
T=5        #s

#Calculation
Tsum1=4*T+8*T
t=1*T
Tsum2=T+2*T+4*T+8*T+16*T+32*T+64*T+128*T

#Result
print"(a)The timing cycle is",Tsum1/60,"min"
print"(b)Minimum programmeble timing cycle is",t,"s"
print"(c)maximum programmable timing cycle is",round(Tsum2,2),"s or 21 min 15 s"

(a)The timing cycle is 1 min
(b)Minimum programmeble timing cycle is 5 s
(c)maximum programmable timing cycle is 1275.0 s or 21 min 15 s

Example 13.10 Page No 391

In [36]:
#Given
T=2.5           #ms

#pin from fig 13-19
p1=1
p2=2
p3=3
p4=4

#Calculation
#Time base rating
t1=T
t2=2*T
t3=4*T
t4=8*T

#Period
P1=2*T
P2=4*T
P3=8*T
P4=16*T

#Frequency
f1=1/(P1)
f2=1/(P2)
f3=1/(P3)
f4=1/(P4)

#Result
print"The frequencies are",f1*1000,"Hz,",f2*1000,"Hz,",f3*1000,"Hz,",f4*1000,"Hz"

The frequencies are 200.0 Hz, 100.0 Hz, 50.0 Hz, 25.0 Hz

Example 13.11 Page No 393

In [38]:
#Given
#From fig 13.11 (a)
T=1         #ms

#Calculation
Tsum=T+4*T
period=Tsum+T
f=1/(period*10**-3)

#Result
print"The frequency is",round(f,1),"Hz"

The frequency is 166.7 Hz