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ECE 233 LAB 9 DIODE CIRCUITS CH1 CH2 I1(t) R1 D1 VDC1 D2 VDC2 R I(t) R2 I2(t) VAC + V(t) - Figure 1: Diode circuit 1 Theoretical analisis for the circuit in Figure 1, (assuming that the diodes are ideal). If V VDC1 then I 1 V VDC1 V VDC1 , I 2 0 and I I 1 I 2 Amper R1 R R1 R If VDC 2 V VDC1 then I1 0 , I 2 0 and I I1 I 2 0 Amper If V VDC 2 then I1 0 , I 2 VDC 2 V V VDC 2 and I I1 I 2 Amper R2 R R2 R Theoretical analisis for the circuit in Figure 1, (assuming that the diodes are not ideal and their threshold values are VT). If V VDC1 VT then I1 V VDC1 VT V VDC1 VT , I 2 0 and I I1 I 2 Amper R1 R R1 R If VDC 2 VT V VDC1 VT then I1 0 , I 2 0 and I I1 I 2 0 Amper If V VDC 2 VT then I1 0 , I 2 VDC 2 VT V V VDC 2 VT and I I1 I 2 Amper R2 R R2 R 1- Construct the circuit in Figure 1 on the breadboard. The circuit parameters are as follows: VDC1=1.5 Volt, VDC2=1.5 Volt, R1=2.2 kΩ, R2=1 kΩ, R= 1 kΩ, VAC=8sin(2πft) Volt (For VDC1 and VDC2 use the small batteries, for VAC use the function generator and take f=1000 Hz). If the channels of the oscilloscope are connected as in Figure 1, CH1 will show the total voltage drow over the circuit whereas CH2 will show the total current over the circuit. Hence, when we use x-y operation on the oscilloscope we will observe the V(t) versus I(t) characteristic for the circuit. For both channels (CH1 and CH2) take Volt/Div= 2 Volt. Draw what you have observed on the oscilloscope in x-y mode to Figure 2, indicate the important points in your plot. Figure 2: Oscilloscope view when Volt/Div=2 Volt for part 1. CH1 CH2 I1(t) R1 D1 VDC1 R D2 R2 I(t) VDC2 I2(t) VAC + V(t) - Figure 3: Diode circuit 2 Theoretical analisis for the circuit in Figure 3, (assuming that the diodes are not ideal and their threshold values are VT and VDC1+VT>VDC2-VT). If V VDC1 VT then I1 V VDC1 VT V VDC1 VT , I 2 0 and I I1 I 2 Amper R1 R R1 R If VDC 2 VT V VDC1 VT then I1 0 , I 2 0 and I I1 I 2 0 Amper VDC 2 VT V V VDC 2 VT and I I1 I 2 Amper R2 R R2 R Theoretical analisis for the circuit in Figure 3, (assuming that the diodes are not ideal and their threshold values are VT and VDC1+VT=VDC2-VT). If V VDC 2 VT then I1 0 , I 2 If V VDC1 VT VDC 2 VT then I1 I I1 I 2 V VDC1 VT , I 2 0 and R1 R V VDC1 VT Amper R1 R If V VDC 2 VT VDC1 VT then I1 0 , I 2 V VDC 2 VT Amper R2 R Theoretical analisis for the circuit in Figure 3, (assuming that the diodes are not ideal and their threshold values are VT and VDC1+VT<VDC2-VT). I I1 I 2 VDC 2 VT V and R2 R V VDC1 VT V VDC 2 VT , I 2 0 and I I1 I 2 Amper R1 R R1 R V VDC1 VT V VT V , I 2 DC 2 and VT then I1 R1 R R2 R If V VDC 2 VT then I1 If VDC1 VT V VDC 2 1 1 VDC1 VT VDC 2 VT Amper I I 1 I 2 V R1 R R2 R R1 R R2 R V VT V If V VDC1 VT then I1 0 , I 2 DC 2 and R2 R V VDC 2 VT Amper I I1 I 2 R2 R 2- a) Construct the circuit in Figure 3 on the breadboard. The circuit parameters are as follows: VDC1=1.5 Volt, VDC2=0 Volt, R1=2.2 kΩ, R2=1 kΩ, R= 1 kΩ, VAC=8sin(2πft) Volt (For VDC1 and VDC2 use the small batteries, for VAC use the function generator and take f=1000 Hz). If the channels of oscilloscope are connected as in Figure 3, CH1 will show the total voltage drow over the circuit whereas CH2 will show the total current over the circuit. Hence, when we use x-y operation on the oscilloscope we will observe the V(t) versus I(t) characteristic for the circuit. For both channels (CH1 and CH2) take Volt/Div= 2 Volt. Draw what you have observed on the oscilloscope in x-y mode to Figure 4, indicate the important points in your plot ( VT 0.7 Volt). Figure 4: Oscilloscope view when Volt/Div=2 Volt for part 2-a. b) Construct the circuit in Figure 3 on the breadboard. The circuit parameters are as follows: VDC1=0 Volt, VDC2=1.5 Volt, R1=2.2 kΩ, R2=1 kΩ, R= 1 kΩ, VAC=8sin(2πft) Volt (For VDC1 and VDC2 use the small batteries, for VAC use the function generator and take f=1000 Hz). If the channels of oscilloscope are connected as in Figure 3, CH1 will show the total voltage drow over the circuit whereas CH2 will show the total current over the circuit. Hence, when we use x-y operation on the oscilloscope we will observe the V(t) versus I(t) characteristic for the circuit. For both channels (CH1 and CH2) take Volt/Div= 2 Volt. Draw what you have observed on the oscilloscope in x-y mode to Figure 5, indicate the important points in your plot. ( VT 0.7 Volt). Figure 5: Oscilloscope view when Volt/Div=2 Volt for part 2-b. c) Construct the circuit in Figure 3 on the breadboard. The circuit parameters are as follows: VDC1=0 Volt, VDC2=3 Volt, R1=2.2 kΩ, R2=1 kΩ, R= 1 kΩ, VAC=8sin(2πft) Volt (For VDC1 and VDC2 use the small batteries, for VAC use the function generator and take f=1000 Hz). If the channels of oscilloscope are connected as in Figure 3, CH1 will show the total voltage drow over the circuit whereas CH2 will show the total current over the circuit. Hence, when we use x-y operation on the oscilloscope we will observe the V(t) versus I(t) characteristic for the circuit. For both channels (CH1 and CH2) take Volt/Div= 2 Volt. Draw what you have observed on the oscilloscope in x-y mode to Figure 6, indicate the important points in your plot. ( VT 0.7 Volt). Figure 6: Oscilloscope view when Volt/Div=2 Volt for part 2-c.