#Variable declaration
VCC=10.0; #Collector supply voltage, V
R1=10.0; #Resistor R1, kilo ohm
R2=2.2; #Resistor R2, kilo ohm
RC=3.6; #Collector resistor, kilo ohm
RE=1.1; #Emitter resistor, kilo ohm
VBE=0.7; #Base-emitter voltage, V
#Calculation
I1=VCC/(R1+R2); #Current through R1 and R2, mA (OHM's LAW)
V2=I1*R2; #Voltage across R2 resistor, V (OHM's LAW)
VE=V2-VBE; #Emitter voltage, V
IE=VE/RE; #Emitter current, mA (OHM's LAW)
IC=IE; #Collector current, mA (approximately equal to emitter current)
I_T=I1+IC; #Total current drawn from the supply, mA
P_dc=VCC*I_T; #Total power drawn from the supply, mW
#Results
print("The total power drawn from the supply=%.1fmW."%P_dc);
#Variable declaration
V_L=10.6; #Voltage across load, V.(from a.c voltmeter, therfore r.m.s value)
R_L=200.0; #Load resistance, ohm
#Calculation
#Since, power =V**2/R,
P_O=(V_L**2/R_L)*1000; #A.C output power, mW
#Result
print("The a.c output power = %.1fmW."%P_O);
#Variable declaration
RL=100.0; #Load resistance, ohm
V_PP=18.0; #Peak-to-peak a.c voltage, V
#Calculation
#Since, V(r.m.s)=(V(peak-to-peak)/2)/sqrt(2)
VL=V_PP/(2*(2**0.5)); #r.m.s value, V
#Since, power=(square of voltage)/resistance
P_O_max=(VL**2/RL)*1000; #Maximum possible a.c load power, mW
#Result
print("The maximum possible a.c load power=%dmW."%P_O_max);
#Variable declaration
V_battery=12.0; #Battery voltage, V
P_out=2.0; #Output power, W
#Calculation
#Since, Power=Current*Voltage
IC=(P_out/V_battery)*1000; #Maximum collector current , mA
#Result
print("The maximum collector current=%.1fmA."%IC);
#Variable declaration
V_battery=12.0; #Battery voltage, V
RL=4.0; #Collector load, kilo ohm
#Calculation
IC_max=V_battery/RL; #Maximum collector current, mA
#Result
print("The maximum collector current=%dmA."%IC_max);
#Variable declaration
P=50.0; #Power supplied by power amplifier, W
R=8.0; #Resistance of speaker, ohm
#Calculation
#(i)
#Since, Power=Voltage _square/Resistance,
V=(P*R)**0.5; #a.c output voltage, V
#(ii)
I=V/R; #a.c output current, A (OHM's LAW)
#Result
print("(i) The a.c output voltage=%dV."%V);
print("(ii) The a.c output current=%.1fA."%I);
#Variable declaration
VCC=20.0; #Collector supply voltage, V
ib_peak=10.0; #Base current(peak), mA
RB=1.0; #Base resistance, kilo ohm
RC=20.0; #Collector resistance, ohm
beta=25.0; #Base current amplification factor
VBE=0.7; #Base-emitter voltage, V
#Calculation
IB=round(VCC-VBE/RB,1); #Base current, mA (OHM's LAW)
IC=int(beta*IB); #Collector current, mA
VCE=VCC-(IC/1000)*RC; #Collector emitter voltage, V (KVL)
#(i)
ic_peak=beta*ib_peak; #Collector current(peak), mA
P_o_ac=(ic_peak/1000)**2*RC/2; #Output power, W
#(ii)
P_dc=VCC*IC/1000; #Input power, W
#(iii)
collector_efficiency=(P_o_ac/P_dc)*100; #Collector efficiency of the amplifier circuit,
#Result
print("(i) The output power=%.3fW."%P_o_ac);
print("(ii) The input power=%.1fW."%P_dc);
print("(iii) The collector efficiency=%.1f%%."%collector_efficiency);
#Variable declaration
P_dc=10.0; #zero signal power dissipation, W
P_o=4.0; #a.c output power, W
#Calculation
#(i)
Collector_eff=(P_o/P_dc)*100; #collector efficiency
#(ii)
#Zero signal power is the maximum power dissipation in a transistor, therefore,
Power_rating=P_dc; #Power rating of the transistor, W
#Result
print("(i) The collector efficiency=%d%%."%Collector_eff);
print("(i) The power rating of the transistor=%dW."%Power_rating);
#Variable declaration
RL=100.0; #Secondary load, ohm
n=10.0; #Transformer turn ratio
IC=100.0; #Zero signal collector current, mA
#Calculation
RL_reflected=n**2*RL; #Reflected load as seen by the primary of the transformer, ohm
P_o_ac_max=(IC/1000)**2*RL_reflected/2; #Maximum a.c power output, W
#Result
print("The maximum a.c power output=%dW."%P_o_ac_max);
#Variable declaration
VCC=5.0; #Collector supply voltage, V
IC=50.0; #Zero signal collector current, mA
#Calculation
#(i)
P_o_max=VCC*IC/2; #Maximum a.c output power, mW
#(ii)
P_dc=VCC*IC; #D.C input power, mW
#Since, maximum power is dissipated in the zero signal conditions
Power_rating=P_dc; #Power rating of transistor, mW
#(iii)
Max_collector_eff=(P_o_max/P_dc)*100; #Maximum collector efficiency
#Result
print("(i) The maximum a.c output power=%dmW"%P_o_max);
print("(ii) The power rating of the transistor=%dmW."%Power_rating);
print("(iii) The maximum collector efficiency =%d%%."%Max_collector_eff);
from math import sqrt
#Variable declaration
ic_max=160.0; #Maximum a.c collector current, mA
ic_min=10.0; #Minimum a.c collector current, mA
vce_max=12.0; #Maximum collector-emitter voltage, V
vce_min=2.0; #Minimum collector-emitter voltage, V
#Calculation
vce_pp=vce_max-vce_min; #peak to peak collector emitter voltage, V
ic_pp=ic_max-ic_min; #peak to peak collector current, V
P_o=(vce_pp/(2*sqrt(2)))*(ic_pp/(2*sqrt(2))); #a.c output power, mW
#Result
print("The a.c output power=%.1fmW."%P_o);
from math import sqrt
#Variable declaration
VCC=12.0; #Battey voltage, V
IC_max_change=100.0; #maximum collector current change, mA
RL=5.0; #Loudspeaker resistance, ohm
#Calculation
VCE_max_change=VCC; #Maximum collector-emitter voltage change
#(i) Loud speaker directly connected in the collector
Vmax_speaker=(IC_max_change/1000)*RL; #Maximum voltage across the loudspeaker, V
P_speaker_directly_coupled=Vmax_speaker*IC_max_change; #Power developed in the loudspeaker,mW
#(ii) Loudspeaker transformer coupled
Z_out=(VCE_max_change/IC_max_change)*1000; #Output impedance of transistor, ohm
#For max power transfer, primary impedance should be Z_out
RL_reflected=Z_out; #Load resistance as seen by primary, ohm
n=sqrt(RL_reflected/RL); #Turns ratio of transformer
Vp=VCC; #Transformer primary voltage, V
Vs=Vp/n; #Transformer secondary voltage, V
IL=Vs/RL; #Load current, A
P_speaker_transformer_coupled=IL**2*RL*1000; #Power delivered to the speaker, mW
#Result
print("(i) The power transferred to the speaker when directly coupled=%dmW."%P_speaker_directly_coupled);
print("(ii) The power trasnferred to the speaker when transformer-coupled=%dmW."%P_speaker_transformer_coupled);
print(" The turns ratio=%.1f."%n);
from math import sqrt
#Variable declaration
beta=100.0; #Base current amplification factor
RL=81.6; #Load resistance, ohm
VCE_peak=30.0; #Peak value of collector voltage, V
IC_peak=35.0; #Peak value of collector current, mA
VCE_min=5.0; #Minimum value of collector voltage, V
IC_min=1.0; #Minimum value of collector current, mA
#Calculation
#(i)
IC_zero_signal=(IC_peak-IC_min)/2 +1; #Zero signal collector current, mA
#(ii)
IB_zero_signal=IC_zero_signal/beta; #Zero signal base current, mA
#(iii)
VCE_zero_signal=(VCE_peak-VCE_min)/2 +5; #Zero signal collector-emitter voltage, V
VCC=VCE_zero_signal; #Collector supply voltage,V (due to transformer coupling, aproximately equal to zero signal VCE)
P_dc=VCC*IC_zero_signal; #d.c input power, mW
VCE_ac=(VCE_peak-VCE_min)/(2*sqrt(2)); #a.c output voltage, V
IC_ac=(IC_peak-IC_min)/(2*sqrt(2)); #a.c output current, mA
P_ac=VCE_ac*IC_ac; #a.c output power, mW
#(iv)
collector_eff=(P_ac/P_dc)*100; #Collector efficiency
#(v)
#a.c resistance RL'=negative inverse of slope of the d.c load line
slope=(IC_peak-IC_min)/(VCE_min-VCE_peak); #Slope of he d.c load line, kilo mho
RL_ac=-(1/slope)*1000; #a.c resistance, ohm
n=sqrt(RL_ac/RL); #Transformer turn ratio
#Result
print("(i) The approximate value of zero signal collector current=%dmA."%IC_zero_signal);
print("(ii) The zero signal base current=%.2fmA."%IB_zero_signal);
print("(iii) The d.c input power= %dmW and a.c output power =%dmW."%(P_dc,P_ac));
print("(iv) The collector efficiency=%.1f%%."%collector_eff);
print("(v) The turn ratio of the transformer=%d."%n);
from math import sqrt
#Variable declaration
RL=13.0; #Load resistance, ohm
RL_reflected=325.0; #Load resistance, when referred to primary, ohm
VCC=20.0; #Supply voltage, V
IC=58.0; #Quiscent value of collector current, mA
#Calculation
#(i)
n=sqrt(RL_reflected/RL); #Transformer turn ratio
#(ii)
P_ac=(((IC/1000)**2)*RL_reflected/2)*1000; #A.C output power, mW
#(iii)
P_dc=VCC*IC; #d.c input power, mW
collector_eff=(P_ac/P_dc)*100; #Collector efficiency
#Result
print("(i) Transformer turn ratio=%d."%n);
print("(ii) The a.c output power=%dmW."%P_ac);
print("(iii) The collector efficiency=%d%%."%collector_eff);
#Variable declaration
P_total=4.0; #Total power dissipated by the power transistor, W
T_j_max=90.0; #Maximum junction temperature, degree celsius
theta=10.0; #Thermal resistance, degree celsius per watt
#Calculation
#Since, Total power dissipation=half of(max. junc. temp. - ambient temp.)
T_amb=T_j_max-(P_total*theta); #Ambient temperature, degree celsius
#Result
print("The ambient temperature=%d degree celsius."%T_amb);
#Variable declaration
theta=300.0; #Thermal resistance, degree celsius per watt
T_j_max=90.0; #Maximum junction temperature, degree celsius
T_amb=30.0; #Ambient temperature, degree celsius
#Calculation
#(i) Without heat sink
P_total=((T_j_max-T_amb)/theta)*1000; #Maximum permissible power dissipation without sink, mW
print("(i)The maximum permissible power dissipation without heat sink=%dmW."%P_total);
#(ii) With heat sink
theta=60.0; #reduced thermal resistance, degree celsius per watt
P_total=((T_j_max-T_amb)/theta)*1000; #Maximum permissible power dissipation with heat sink, mW
print("(ii)The maximum permissible power dissipation with heat sink=%dmW."%P_total);
#Variable declaration
theta=20.0; #Thermal resistance, degree celsius per watt
T_j_max=200.0; #Maximum junction temperature, degree celsius
T_amb=25.0; #Ambient temperature, degree celsius
VCE=4.0; #Collector-emitter voltage, V
#Calculation
P_total=(T_j_max-T_amb)/theta; #Maximum permissible power dissipation, W
#since, the max. power dissipation=VCE_max*IC_max,therefore
IC_max=P_total/VCE; #Maximum collector current, A
print("The maximum collector current that the transistor can carry without destruction=%.2fA."%IC_max);
#The ambient temperature rises
T_amb=75.0; #The risen ambibent temperature, degree celsius
P_total=(T_j_max-T_amb)/theta; #Maximum permissible power dissipation, W
IC_max=P_total/VCE; #Maximum collector current, A
print("The maximum collector current for the risen ambient temperature=%.2fA."%IC_max);
from math import pi
#Variable declaration
VCC=12.0; #Supply voltage, V
RL=8.0; #Driving load, ohm
#Calculation
#(i)
IC_sat=VCC/(2*RL); #Collector saturation current, A
P_o_max=round(VCC*IC_sat*0.25,2); #Maximum load power, W
#(ii)
P_dc=round(VCC*IC_sat/round(pi,2),2); #d.c input power, W
#(iii)
Collector_eff=(P_o_max/P_dc)*100; #Collector efficiency
#Result
print("(i) The maximum load power =%.2fW."%P_o_max);
print("(ii) The d.c input power=%.2fW."%P_dc);
print("(iii) The collector efficiency=%.1f%%."%Collector_eff);
#Variable declaration
P_T=10.0; #Power rating of each transistor, W
max_eff=0.785; #Maximum collector effciency
#Calculation
#Since, input power=max. a.c power + Power rating of transistor
#And, max. efficiency=max. a.c power/input d.c power
P_2T=2*P_T; #Total power dissipation by two transistors
P_o_max=(max_eff*P_2T)/(1-max_eff); #Maximum output a.c power, W
#result
print("The maximum output power that can be obtained=%.2fW."%P_o_max);
#Variable declaration
eff=60.0/100; #Efficiency of the amplifier
P_T=2.5; #Power dissipated by each transistor, W
#Calculation
#Since, input power=max. a.c power + Power rating of transistor
#And, max. efficiency=max. a.c power/input d.c power
P_2T=2*P_T; #Total power dissipated by both transistors, W
P_ac=(eff*P_2T)/(1-eff); #Output a.c power, W
P_dc=P_ac+P_2T; #Input d.c power, W
#Result
print("The a.c output power= %.1fW."%P_ac);
print("The d.c input power= %.1fW."%P_dc);
#Variable declaration
VCC=10.0; #Supply voltage, V
RL=10.0; #Load resistance, ohm
#Calculation
IC_sat=(VCC/(2*RL))*1000; #Saturated collector current, mA
VCE_off=VCC/2; #Collector-emitter voltage in off state, V
#Result
print("1st end point of a.c load line, IC(sat)=%dmA."%IC_sat);
print("2nd end point of a.c load line, VCE(off)=%dV."%VCE_off);