From b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b Mon Sep 17 00:00:00 2001
From: priyanka
Date: Wed, 24 Jun 2015 15:03:17 +0530
Subject: initial commit / add all books

---
 3507/CH12/EX12.1/Ex12_1.sce   | 26 ++++++++++++++++++++++++++
 3507/CH12/EX12.10/Ex12_10.sce | 17 +++++++++++++++++
 3507/CH12/EX12.11/Ex12_11.sce | 27 +++++++++++++++++++++++++++
 3507/CH12/EX12.12/Ex12_12.sce | 29 +++++++++++++++++++++++++++++
 3507/CH12/EX12.13/Ex12_13.sce | 28 ++++++++++++++++++++++++++++
 3507/CH12/EX12.14/Ex12_14.sce | 23 +++++++++++++++++++++++
 3507/CH12/EX12.15/Ex12_15.sce | 29 +++++++++++++++++++++++++++++
 3507/CH12/EX12.16/Ex12_16.sce | 27 +++++++++++++++++++++++++++
 3507/CH12/EX12.17/Ex12_17.sce | 25 +++++++++++++++++++++++++
 3507/CH12/EX12.18/Ex12_18.sce | 19 +++++++++++++++++++
 3507/CH12/EX12.19/EX12_19.sce |  8 ++++++++
 3507/CH12/EX12.2/Ex12_2.sce   | 15 +++++++++++++++
 3507/CH12/EX12.20/Ex12_20.sce | 30 ++++++++++++++++++++++++++++++
 3507/CH12/EX12.21/Ex12_21.sce | 24 ++++++++++++++++++++++++
 3507/CH12/EX12.22/Ex12_22.sce | 22 ++++++++++++++++++++++
 3507/CH12/EX12.23/Ex12_23.sce | 32 ++++++++++++++++++++++++++++++++
 3507/CH12/EX12.24/Ex12_24.sce | 16 ++++++++++++++++
 3507/CH12/EX12.25/Ex12_25.sce |  5 +++++
 3507/CH12/EX12.26/Ex12_26.sce | 13 +++++++++++++
 3507/CH12/EX12.3/Ex12_3.sce   | 27 +++++++++++++++++++++++++++
 3507/CH12/EX12.4/Ex12_4.sce   | 28 ++++++++++++++++++++++++++++
 3507/CH12/EX12.5/Ex12_5.sce   | 23 +++++++++++++++++++++++
 3507/CH12/EX12.6/Ex12_6.sce   | 22 ++++++++++++++++++++++
 3507/CH12/EX12.7/Ex12_7.sce   | 20 ++++++++++++++++++++
 3507/CH12/EX12.8/Ex12_8.sce   | 19 +++++++++++++++++++
 3507/CH12/EX12.9/Ex12_9.sce   | 31 +++++++++++++++++++++++++++++++
 3507/CH12/EX19.12/Ex19_12.sce | 11 +++++++++++
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 create mode 100644 3507/CH12/EX12.10/Ex12_10.sce
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 create mode 100644 3507/CH12/EX12.12/Ex12_12.sce
 create mode 100644 3507/CH12/EX12.13/Ex12_13.sce
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 create mode 100644 3507/CH12/EX12.17/Ex12_17.sce
 create mode 100644 3507/CH12/EX12.18/Ex12_18.sce
 create mode 100644 3507/CH12/EX12.19/EX12_19.sce
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 create mode 100644 3507/CH12/EX12.9/Ex12_9.sce
 create mode 100644 3507/CH12/EX19.12/Ex19_12.sce

(limited to '3507/CH12')

diff --git a/3507/CH12/EX12.1/Ex12_1.sce b/3507/CH12/EX12.1/Ex12_1.sce
new file mode 100644
index 000000000..78ed01951
--- /dev/null
+++ b/3507/CH12/EX12.1/Ex12_1.sce
@@ -0,0 +1,26 @@
+// chapter 12
+// example 12.1
+// page 235
+
+V_CC=6 // V
+R_C=2.5 // kilo ohm
+
+// for faithful amplification V_CE should not be less than V_CC for Si transistor so
+V_max=V_CC-1
+I_max=V_max/R_C
+
+// As negative and positive half cyces of input are equal, change in collector current will be equal and opposite so
+I_min=I_max/2
+
+printf("Maximum allowable collector current = %.3f mA \n",I_max)
+printf("Minimum zero signal collector current = %.3f mA \n",I_min)
+
+// the circuit diagram is constructed on xcos and its screenshot has been taken.
+// the waveform given can not be obtained in xcos unless we assume necessary values as data is insufficient for plotting graph in scilab.
+// so waveform is constructed as below
+
+clf()
+x=linspace(1,5*%pi,100)
+[t]=sin(x)+1
+plot(x,[t])
+xtitle("max and min allowable collector currents","t","i_c (mA)") 
diff --git a/3507/CH12/EX12.10/Ex12_10.sce b/3507/CH12/EX12.10/Ex12_10.sce
new file mode 100644
index 000000000..7ec23c585
--- /dev/null
+++ b/3507/CH12/EX12.10/Ex12_10.sce
@@ -0,0 +1,17 @@
+//chapter12
+//example12.10
+//page246
+
+V_BE=0.7 // V
+gain_beta=100
+I_C=1 // mA
+V_CE=2 // V
+
+I_B=I_C/gain_beta
+
+// since V_CE=V_BE+V_CB we get
+V_CB=V_CE-V_BE
+
+R_B=V_CB/I_B
+
+printf("base resistance=%.3f kilo ohm \n",R_B)
diff --git a/3507/CH12/EX12.11/Ex12_11.sce b/3507/CH12/EX12.11/Ex12_11.sce
new file mode 100644
index 000000000..d8099712f
--- /dev/null
+++ b/3507/CH12/EX12.11/Ex12_11.sce
@@ -0,0 +1,27 @@
+//chapter12
+//example12.11
+//page248
+
+Vcc=15 // V
+Re=2 // kilo ohm
+Rc=1 // kilo ohm
+gain_beta=100
+Vbe=0.7 // V
+R1=10 // kilo ohm
+R2=5 // kilo ohm
+
+// when Ic=0, Vce=Vcc i.e. Vce=6 and when Vce=0, Ic=Vcc/(Rc+Re) i.e. Ic=15/(1+2)
+// so equation of load line becomes Ic=-(1/3)*Vce+5
+
+clf()
+x=linspace(0,15,5)
+y=-(1/3)*x+5
+plot2d(x,y,style=3,rect=[0,0,16,6])
+xtitle("dc load line","Vce(volts)","Ic(mA)")
+
+V2=Vcc*R2/(R1+R2) // voltage across R2 i.e. 5 kilo ohm
+Ie=(V2-Vbe)/Re
+Ic=Ie
+Vce=Vcc-Ic*(Rc+Re)
+
+printf("the operating point is %.3f V and %.3f mA \n",Vce,Ic)
diff --git a/3507/CH12/EX12.12/Ex12_12.sce b/3507/CH12/EX12.12/Ex12_12.sce
new file mode 100644
index 000000000..75c4b3b09
--- /dev/null
+++ b/3507/CH12/EX12.12/Ex12_12.sce
@@ -0,0 +1,29 @@
+//chapter12
+//example12.12
+//page249
+
+Vcc=15 // V
+Re=2 // kilo ohm
+Rc=1 // kilo ohm
+gain_beta=100
+Vbe=0.7 // V
+R1=10 // kilo ohm
+R2=5 // kilo ohm
+
+Eo=Vcc*R2/(R1+R2)
+Ro=R1*R2/(R1+R2)
+
+printf("thevenin voltage = %.3f V \n",Eo)
+printf("thevenin resistance = %.3f kilo ohm \n",Ro)
+
+// here Eo=Ib*Ro+Vbe+Ie*Re
+// now considering Ie=gain_beta*Ib, and making Ib as subject we get
+// Ib=(Eo-Vbe)/(Ro+gain_beta*Re)
+// Ic=gain_beta*Ib=gain_beta*(Eo-Vbe)/(Ro+gain_beta*Re)
+// dividing numerator and denominator by gain_beta we get
+// Ic=(Eo-Vbe)/(Re+Ro/gain_beta)
+// Ro/gain_beta is negligible compared to Re so
+Ic=(Eo-Vbe)/Re
+Vce=Vcc-Ic*(Rc+Re)
+
+printf("the operating point is %.3f V and %.3f mA \n",Vce,Ic)
diff --git a/3507/CH12/EX12.13/Ex12_13.sce b/3507/CH12/EX12.13/Ex12_13.sce
new file mode 100644
index 000000000..c8d7bae0f
--- /dev/null
+++ b/3507/CH12/EX12.13/Ex12_13.sce
@@ -0,0 +1,28 @@
+//chapter12
+//example12.13
+//page250
+
+R1=50 // kilo ohm
+R2=10 // kilo ohm
+Re=1 // kilo ohm
+Vcc=12 // V
+Vbe1=0.1 // V
+Vbe2=0.3 // V
+
+V2=Vcc*R2/(R1+R2) // voltage across R2
+
+// for Vbe=0.1 V
+Ic1=(V2-Vbe1)/Re
+
+// for Vbe=0.3 V
+Ic2=(V2-Vbe2)/Re
+
+printf("for V_BE=0.1 V, collector current = %.3f mA \n",Ic1)
+printf("for V_BE=0.3 V, collector current = %.3f mA \n \n",Ic2)
+
+Vbe_change=100*(Vbe2-Vbe1)/Vbe1
+Ic_change=-100*(Ic2-Ic1)/Ic1 // negative sign since Ic decreases
+printf("comment : if V_BE changes by %.5f percent, \ncollector current changes by %.3f percent \n",Vbe_change,Ic_change)
+printf("so collector current is independent of transistor parameter variations \n")
+
+// the change in V_BE is 200 percent not 300 percent.It is mistake in textbook
diff --git a/3507/CH12/EX12.14/Ex12_14.sce b/3507/CH12/EX12.14/Ex12_14.sce
new file mode 100644
index 000000000..df5ab4cff
--- /dev/null
+++ b/3507/CH12/EX12.14/Ex12_14.sce
@@ -0,0 +1,23 @@
+//chapter12
+//example12.14
+//page251
+
+Vcc=20 // V
+Re=5 // kilo ohm
+Rc=1 // kilo ohm
+Vbe=0 // considering it as negligible
+R1=10 // kilo ohm
+R2=10 // kilo ohm
+
+V2=Vcc*R2/(R1+R2)
+
+// since V2=Vbe+Ie*Re so 
+Ie=(V2-Vbe)/Re
+Ic=Ie
+
+Vce=Vcc-Ic*(Rc+Re)
+Vc=Vcc-Ic*Rc
+
+printf("emitter current = %.3f mA \n",Ie)
+printf("collector emitter voltage = %.3f V \n",Vce)
+printf("collector potential = %.3f V \n",Vc)
diff --git a/3507/CH12/EX12.15/Ex12_15.sce b/3507/CH12/EX12.15/Ex12_15.sce
new file mode 100644
index 000000000..a998d17bd
--- /dev/null
+++ b/3507/CH12/EX12.15/Ex12_15.sce
@@ -0,0 +1,29 @@
+//chapter12
+//example12.15
+//page252
+
+R_C=2.2 // kilo ohm
+V_CC=9 // V
+gain_beta=50
+V_BE=0.3 // V
+I_C=2 // mA
+V_CE=3 // V
+
+I_B=I_C/gain_beta
+I1=10*I_B
+
+// I1=V_CC/(R1+R2) so let Rt=R1+R2 thus we get
+Rt=V_CC/I1
+
+// by Kirchoff voltage law to collector side we get
+// V_CC=I_C*R_C+V_CE+I_E*R_E and also we have I_C=I_E so
+// V_CC=I_C*R_C+V_CE+I_C*R_E so making R_E as subject we get
+R_E=((V_CC-V_CE)/I_C)-R_C // in kilo ohm
+
+V2=V_BE+I_C*R_E // since V_E=I_C*R_E
+R2=V2/I1
+R1=Rt-R2
+
+printf("emitter resistance = %.3f ohm \n",R_E*1000)
+printf("R1 = %3f kilo ohm \n",R1)
+printf("R2 = %3f kilo ohm \n",R2)
diff --git a/3507/CH12/EX12.16/Ex12_16.sce b/3507/CH12/EX12.16/Ex12_16.sce
new file mode 100644
index 000000000..fc7a9eb5a
--- /dev/null
+++ b/3507/CH12/EX12.16/Ex12_16.sce
@@ -0,0 +1,27 @@
+//chapter12
+//example12.16
+//page252
+
+alpha=0.985
+V_BE=0.3 // V
+V_CC=16 // V
+V_CE=6 // V
+I_C=2 // mA
+R_E=2 // kilo ohm
+R2=20 // kilo ohm
+
+gain_beta=alpha/(1-alpha)
+I_B=I_C/gain_beta
+
+V_E=I_C*R_E
+V2=V_BE+V_E
+V1=V_CC-V2
+
+I1=V2/R2
+R1=V1/I1
+
+V_RC=V_CC-V_CE-V_E
+R_C=V_RC/I_C
+
+printf("R1 = %.3f kilo ohm \n",R1)
+printf("collector resistance = %.3f kilo ohm \n",R_C)
diff --git a/3507/CH12/EX12.17/Ex12_17.sce b/3507/CH12/EX12.17/Ex12_17.sce
new file mode 100644
index 000000000..81fb8181e
--- /dev/null
+++ b/3507/CH12/EX12.17/Ex12_17.sce
@@ -0,0 +1,25 @@
+//chapter12
+//example12.17
+//page253
+
+Vcc=15 // V
+Re=2 // kilo ohm
+Rc=1 // kilo ohm
+gain_beta=100
+Vbe=0.7 // V
+R1=10 // kilo ohm
+R2=5 // kilo ohm
+
+Eo=Vcc*R2/(R1+R2)
+Ro=R1*R2/(R1+R2)
+
+printf("thevenin voltage = %.3f V \n",Eo)
+printf("thevenin resistance = %.3f kilo ohm \n",Ro)
+
+// here Eo=Ib*Ro+Vbe+Ie*Re
+// now considering Ie=gain_beta*Ib, we can replace Ib=Ie/gain_beta
+// Eo=(Ie/gain_beta)*Ro+Vbe+Ie*Re
+// making Ie as subject we get
+Ie=(Eo-Vbe)/(Re+Ro/gain_beta)
+
+printf("emitter current = %.3f mA \n",Ie)
diff --git a/3507/CH12/EX12.18/Ex12_18.sce b/3507/CH12/EX12.18/Ex12_18.sce
new file mode 100644
index 000000000..c08002fc1
--- /dev/null
+++ b/3507/CH12/EX12.18/Ex12_18.sce
@@ -0,0 +1,19 @@
+//chapter12
+//example12.18
+//page254
+
+V_CC=10 // V
+V_BE=0.2 // V
+I_E=2 // mA
+I_B=50d-3 // mA
+R_E=1 // kilo ohm
+R2=10 // kilo ohm
+
+V2=V_BE+I_E*R_E
+I2=V2/R2
+
+I1=I2+I_B
+V1=V_CC-V2
+R1=V1/I1
+
+printf("R1 = %.3f kilo ohm \n",R1)
diff --git a/3507/CH12/EX12.19/EX12_19.sce b/3507/CH12/EX12.19/EX12_19.sce
new file mode 100644
index 000000000..e93146d97
--- /dev/null
+++ b/3507/CH12/EX12.19/EX12_19.sce
@@ -0,0 +1,8 @@
+//chapter12
+//example12.19
+//page255
+
+printf(" i) if R2 is shorted, base will be grounded. It will be \n    left without forward bias and transistor \n    will be cutoff so output is zero.\n \n")
+printf(" ii) if R2 is open,forward bias will be very high. The \n    collector current will be very high and collector \n    emitter voltage will be very low. \n \n")
+printf(" iii) if R1 is shorted, transistor will be in saturation \n    due to excessive forward bias. The base will be at \n    Vcc and emitter will be slightly below Vcc.\n \n")
+printf(" iv) if R1 is open, transistor will be without forward bias.\n    Hence transistor will be cutoff i.e. output will be zero. \n")
diff --git a/3507/CH12/EX12.2/Ex12_2.sce b/3507/CH12/EX12.2/Ex12_2.sce
new file mode 100644
index 000000000..4527c8cfd
--- /dev/null
+++ b/3507/CH12/EX12.2/Ex12_2.sce
@@ -0,0 +1,15 @@
+//chapter12
+//example12.2
+//page236
+
+Vcc=13 // V
+V_knee=1 // V
+Rc=4 // kilo ohm
+gain_beta=100
+
+V_Rc=Vcc-V_knee
+Ic=V_Rc/Rc
+Ib=Ic/gain_beta
+Vs=Ic/5 // since Ic/Vs = 5 mA/V given
+
+printf("maximum input signal voltage = %.3f V or %.3f mV \n",Vs,Vs*1000)
diff --git a/3507/CH12/EX12.20/Ex12_20.sce b/3507/CH12/EX12.20/Ex12_20.sce
new file mode 100644
index 000000000..400a639a1
--- /dev/null
+++ b/3507/CH12/EX12.20/Ex12_20.sce
@@ -0,0 +1,30 @@
+//chapter12
+//example12.20
+//page256
+
+Vcc=8 // V
+Rb=360 // kilo ohm
+Rc=2 // kilo ohm
+gain_beta=100
+Vbe=0.7 // V
+
+// when Ic=0, Vce=Vcc i.e. Vce=8 and when Vce=0, Ic=Vcc/Rc i.e. Ic=8/2
+// so equation of load line becomes Ic=-0.5*Vce+4
+
+clf()
+x=linspace(0,8,5)
+y=-0.5*x+4
+plot2d(x,y,style=3,rect=[0,0,9,5])
+xtitle("dc load line","Vce(volts)","Ic(mA)")
+
+// since Vcc=Ib*Rb+Vbe we get
+Ib=(Vcc-Vbe)/Rb
+Ic=Ib*gain_beta
+Vce=Vcc-Ic*Rc
+
+printf("the operating point is %.3f V and %.3f mA \n",Vce,Ic)
+if Vce<Vcc/2+0.1 | Vce>Vcc/2-0.1 // check if V_CE is nearly half of V_CC
+    printf("circuit is mid-point biased \n")
+else 
+    printf("circuit is not mid-point biased. \n")
+end
diff --git a/3507/CH12/EX12.21/Ex12_21.sce b/3507/CH12/EX12.21/Ex12_21.sce
new file mode 100644
index 000000000..e2afa4d54
--- /dev/null
+++ b/3507/CH12/EX12.21/Ex12_21.sce
@@ -0,0 +1,24 @@
+//chapter12
+//example12.21
+//page257
+
+V_CC=10 // V
+R1=12 // kilo ohm
+R2=2.7 // kilo ohm
+V_BE=0.7 // V
+R_E=180d-3 // kilo ohm
+R_C=620d-3 // kilo ohm
+
+V2=V_CC*R2/(R1+R2)
+I_E=(V2-V_BE)/R_E
+I_C=I_E
+V_CE=V_CC-I_C*(R_C+R_E)
+
+printf("the operating point is %.3f V and %.3f mA \n",V_CE,I_C)
+if V_CE<V_CC/2+0.1 | V_CE>V_CC/2-0.1  // check if V_CE is nearly half of V_CC
+    printf("circuit is mid-point biased \n")
+else 
+    printf("circuit is not mid-point biased. \n")
+end
+
+// the accurate answer for collector current is 6.315 mA but in book it is given as 6.33 mA
diff --git a/3507/CH12/EX12.22/Ex12_22.sce b/3507/CH12/EX12.22/Ex12_22.sce
new file mode 100644
index 000000000..5df65f147
--- /dev/null
+++ b/3507/CH12/EX12.22/Ex12_22.sce
@@ -0,0 +1,22 @@
+//chapter12
+//example12.22
+//page257
+
+V_CC=10 // V
+R1=1.5 // kilo ohm
+R2=0.68 // kilo ohm
+R_E=0.24 // kilo ohm
+V_BE=0.7 // V
+beta_min=100
+beta_max=400
+
+V2=V_CC*R2/(R1+R2)
+I_E=(V2-V_BE)/R_E
+I_C=I_E
+
+beta_avg=(beta_min*beta_max)^0.5
+I_B=I_E/(beta_avg+1)
+
+printf("base current = %f micro ampere \n",I_B*1000)
+
+// the accurate answer for base current is 50.151 micro ampere but in book it is given as 49.75 micro ampere
diff --git a/3507/CH12/EX12.23/Ex12_23.sce b/3507/CH12/EX12.23/Ex12_23.sce
new file mode 100644
index 000000000..451224a5e
--- /dev/null
+++ b/3507/CH12/EX12.23/Ex12_23.sce
@@ -0,0 +1,32 @@
+//chapter12
+//example12.23
+//page258
+
+gain_beta=40
+I_C1=2 // mA
+t1=25 // degrees
+t2=55 // degrees
+I_CBO1=5d-3 // mA
+
+// for I_CBO=5 micro ampere at 25 degrees
+I_CEO1=(1+gain_beta)*I_CBO1
+
+I_CBO2=I_CBO1*2^((t2-t1)/10) // since it doubles every 10 degrees. So for t2-t1, it becomes 2^((t2-t1)/10) times.
+I_CEO2=(1+gain_beta)*I_CBO2
+I_C2=I_CEO2+I_C1
+I_C_change=100*(I_C2-I_C1)/I_C1
+
+// for I_CBO=0.1 micro ampere at 25 degrees
+t1_dash=25 // degrees
+t2_dash=55 // degrees
+I_CBO1_dash=0.1d-3 // mA
+I_C1_dash=2 // mA
+
+I_CBO2_dash=I_CBO1_dash*2^((t2-t1)/10) // since it doubles every 10 degrees. So for t2-t1, it becomes 2^((t2-t1)/10) times.
+I_CEO2_dash=(1+gain_beta)*I_CBO2_dash
+I_C2_dash=I_CEO2_dash+I_C1_dash
+I_C_change_dash=100*(I_C2_dash-I_C1_dash)/I_C1_dash
+
+printf("collector cutoff current = %.3f mA \n \n",I_CEO1)
+printf("percent change in zero signal current given that \nI_CBO=5 micro ampere at 25 degree is = %.3f percent \n \n",I_C_change)
+printf("percent change in zero signal current given that \nI_CBO=0.01 micro ampere at 25 degree is = %.3f percent \n",I_C_change_dash)
diff --git a/3507/CH12/EX12.24/Ex12_24.sce b/3507/CH12/EX12.24/Ex12_24.sce
new file mode 100644
index 000000000..a52928277
--- /dev/null
+++ b/3507/CH12/EX12.24/Ex12_24.sce
@@ -0,0 +1,16 @@
+//chapter12
+//example12.24
+//page259
+
+alpha=0.99
+I_E=1 // mA
+t1=27 // degrees
+t2=57 // degrees
+I_CBO1=0.02d-3 // mA
+
+I_CBO2=I_CBO1*2^((t2-t1)/6) // since it doubles every 6 degrees. So for t2-t1, it becomes 2^((t2-t1)/6) times.
+
+I_C=alpha*I_E+I_CBO2
+I_B=I_E-I_C
+
+printf("base current = %.1f micro ampere",I_B*1000)
diff --git a/3507/CH12/EX12.25/Ex12_25.sce b/3507/CH12/EX12.25/Ex12_25.sce
new file mode 100644
index 000000000..3e903c684
--- /dev/null
+++ b/3507/CH12/EX12.25/Ex12_25.sce
@@ -0,0 +1,5 @@
+//chapter12
+//example12.25
+//page261
+
+printf("since base voltage is zero, it means that there is no path \nfor current in the base circuit. So the transistor will be off i.e. I_C=0,I_E=0. \nSo V_C=10V and V_E=0.\nSo obvious fault is R1 is open.\n")
diff --git a/3507/CH12/EX12.26/Ex12_26.sce b/3507/CH12/EX12.26/Ex12_26.sce
new file mode 100644
index 000000000..94b923c6b
--- /dev/null
+++ b/3507/CH12/EX12.26/Ex12_26.sce
@@ -0,0 +1,13 @@
+//chapter12
+//example12.26
+//page261
+
+R1=18 // kilo ohm
+R2=4.7 // kilo ohm
+Re=1 // kilo ohm
+Vcc=10 // V
+
+V_B=Vcc*R2/(R1+R2)
+
+printf("voltage at base = %.3f V \n",V_B)
+printf("The fact that V_C=10V and V_E is nearly equal to V_B reveals \nthat I_C=0 and I_E=0.So I_B drops to zero.So obvious fault is R_E is open. \n")
diff --git a/3507/CH12/EX12.3/Ex12_3.sce b/3507/CH12/EX12.3/Ex12_3.sce
new file mode 100644
index 000000000..e66d126c1
--- /dev/null
+++ b/3507/CH12/EX12.3/Ex12_3.sce
@@ -0,0 +1,27 @@
+//chapter12
+//example12.3
+//page240
+
+Vbb=2 // V
+Vcc=9 // V
+Rc=2 // kilo ohm
+Rb=100 // kilo ohm
+gain_beta=50
+
+// by Kirchoff voltage law on base side, we get Ib*Rb+Vbe=Vbb so
+Ib=Vbb/Rb // Vbe is negligible
+Ic=gain_beta*Ib
+
+// by Kirchoff voltage law on collector side, we get Ic*Rc+Vce=Vcc so
+Vce=Vcc-Ic*Rc
+
+// now for Rb=50 kilo ohm
+Rb2=50 // kilo ohm
+
+// since Rb is halved, Ib is doubled so
+Ib2=2*Ib 
+Ic2=Ib2*gain_beta
+Vce2=Vcc-Ic2*Rc
+
+printf("for Rb = 100 kilo ohm, collector current = %.3f mA \nand collector emitter voltage = %.3f V \n \n",Ic,Vce)
+printf("for Rb = 50 kilo ohm, collector current = %.3f mA \nand collector emitter voltage = %.3f V \n",Ic2,Vce2)
diff --git a/3507/CH12/EX12.4/Ex12_4.sce b/3507/CH12/EX12.4/Ex12_4.sce
new file mode 100644
index 000000000..6874d8acd
--- /dev/null
+++ b/3507/CH12/EX12.4/Ex12_4.sce
@@ -0,0 +1,28 @@
+//chapter12
+//example12.4
+//page241
+
+Vcc=6 // V
+Rb=530 // kilo ohm
+Rc=2 // kilo ohm
+gain_beta=100
+Vbe=0.7 // V
+
+// when Ic=0, Vce=Vcc i.e. Vce=6 and when Vce=0, Ic=Vcc/Rc i.e. Ic=6/2
+// so equation of load line becomes Ic=-0.5*Vce+3
+
+x=linspace(0,6,5)
+y=-0.5*x+3
+plot2d(x,y,style=3,rect=[0,0,7,4])
+xtitle("dc load line","Vce(volts)","Ic(mA)")
+
+// since Vcc=Ib*Rb+Vbe we get
+Ib=(Vcc-Vbe)/Rb
+Ic=Ib*gain_beta
+Vce=Vcc-Ic*Rc
+
+printf("the operating point is %.3f V and %.3f mA \n",Vce,Ic)
+
+stability_factor=gain_beta+1
+
+printf("stability factor=%.1f \n",stability_factor)
diff --git a/3507/CH12/EX12.5/Ex12_5.sce b/3507/CH12/EX12.5/Ex12_5.sce
new file mode 100644
index 000000000..8d8b2f445
--- /dev/null
+++ b/3507/CH12/EX12.5/Ex12_5.sce
@@ -0,0 +1,23 @@
+//chapter12
+//example12.5
+//page242
+
+Vcc=12 // V
+gain_beta=100
+Vbe=0.3 // V
+Ic=1 // mA
+
+// since gain_beta=Ic/Ib
+Ib=Ic/gain_beta
+
+// since Vcc=Ib*Rb+Vbe we get
+Rb=(Vcc-Vbe)/Ib
+
+gain_beta2=50
+
+// since Vcc=Ib*Rb+Vbe we get
+Ib2=(Vcc-Vbe)/Rb
+Ic2=Ib2*gain_beta2
+
+printf("for beta = 100, base resistor = %.3f kilo ohm \n",Rb)
+printf("for beta = 50, zero signal collector current for same Rb is = %.3f mA \n",Ic2)
diff --git a/3507/CH12/EX12.6/Ex12_6.sce b/3507/CH12/EX12.6/Ex12_6.sce
new file mode 100644
index 000000000..cacf6eac8
--- /dev/null
+++ b/3507/CH12/EX12.6/Ex12_6.sce
@@ -0,0 +1,22 @@
+//chapter12
+//example12.6
+//page242
+
+Vcc=10 // V
+R_B=1d3 // kilo ohm
+R_E=1 // kilo ohm
+Vbe=0 // since it is negligible
+gain_beta=100
+
+// by Kirchoff voltage law to base side we get Vcc=I_B*R_B+Vbe+I_E*R_E
+// but I_E=I_B+I_C and I_C=gain_beta*I_B
+// so we get Vcc=I_B*R_B+Vbe+R_E*I_B*(1+gain_beta)
+// making I_B as subject we get
+
+I_B=(Vcc-Vbe)/(R_B+R_E*(1+gain_beta)) // in ampere
+I_C=gain_beta*I_B // in ampere
+I_E=I_C+I_B // in ampere
+
+printf("base current = %.4f mA \n",I_B)
+printf("collector current = %.4f mA \n",I_C)
+printf("emitter current = %.4f mA \n",I_E)
diff --git a/3507/CH12/EX12.7/Ex12_7.sce b/3507/CH12/EX12.7/Ex12_7.sce
new file mode 100644
index 000000000..22eace9cd
--- /dev/null
+++ b/3507/CH12/EX12.7/Ex12_7.sce
@@ -0,0 +1,20 @@
+//chapter12
+//example12.7
+//page243
+
+V_CC=15 // V
+gain_beta=100
+V_BE=0.6 // V
+V_CE=8  // V
+I_C=2 // mA
+
+// here V_CC=V_CE+I_C*R_C so we get
+R_C=(V_CC-V_CE)/I_C
+
+I_B=I_C/gain_beta
+
+// also V_CC=I_B*R_B+V_BE so we get
+R_B=(V_CC-V_BE)/I_B
+
+printf("collector resistance = %.3f kilo ohm \n",R_C)
+printf("base resistance = %.3f kilo ohm \n",R_B)
diff --git a/3507/CH12/EX12.8/Ex12_8.sce b/3507/CH12/EX12.8/Ex12_8.sce
new file mode 100644
index 000000000..bd17c8763
--- /dev/null
+++ b/3507/CH12/EX12.8/Ex12_8.sce
@@ -0,0 +1,19 @@
+//chapter12
+//example12.8
+//page245
+
+V_CC=20 // V
+R_B=100 // kilo ohm
+R_C=1 // kilo ohm
+V_BE=0.7 // V
+
+// we know that R_B=(V_CC-V_BE-gain_beta*R_C*I_B)/I_B so we get
+I_B=(V_CC-V_BE)/(R_B+gain_beta*R_C)
+
+I_C=gain_beta*I_B
+
+V_CE=V_CC-I_C*R_C
+
+printf("operating point is %.3f V, %.3f mA \n",V_CE,I_C)
+
+// the accurate answer is 10.35V,9.65mA but in book it is given as 10.4V,9.6mA
diff --git a/3507/CH12/EX12.9/Ex12_9.sce b/3507/CH12/EX12.9/Ex12_9.sce
new file mode 100644
index 000000000..b49db335a
--- /dev/null
+++ b/3507/CH12/EX12.9/Ex12_9.sce
@@ -0,0 +1,31 @@
+//chapter12
+//example12.9
+//page245
+
+V_CC=12 // V
+gain_beta1=100
+gain_beta2=50
+V_BE=0.3 // V
+V_CE=8  // V
+I_C=1 // mA
+
+// here V_CC=V_CE+I_C*R_C so we get
+R_C=(V_CC-V_CE)/I_C
+
+I_B=I_C/gain_beta1
+
+// we know that R_B=(V_CC-V_BE-gain_beta1*R_C*I_B)/I_B so
+R_B=(V_CC-V_BE-gain_beta1*R_C*I_B)/I_B
+
+
+// for gain_beta=50 i.e. gain_beta2
+
+// we know that R_B=(V_CC-V_BE-gain_beta2*R_C*I_B)/I_B so we get
+I_B2=(V_CC-V_BE)/(R_B+gain_beta2*R_C)
+
+I_C2=gain_beta2*I_B2
+
+V_CE2=V_CC-I_C2*R_C
+
+printf("for beta=100,required base resistance = %.3f kilo ohm \n",R_B)
+printf("for beta=50,new operating point is %.3f V, %.3f mA \n",V_CE2,I_C2)
diff --git a/3507/CH12/EX19.12/Ex19_12.sce b/3507/CH12/EX19.12/Ex19_12.sce
new file mode 100644
index 000000000..7d1341b7a
--- /dev/null
+++ b/3507/CH12/EX19.12/Ex19_12.sce
@@ -0,0 +1,11 @@
+//chapter19
+//example19.12
+//page424
+
+It=8.93 // A
+Ic=8 // A
+
+// we know that (It/Ic)^2=1+m^2/2 so making m as subject we get
+m=(2*((It/Ic)^2-1))^0.5
+
+printf("modulation factor = %.3f or %.3f percent \n",m,m*100)
-- 
cgit