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Experiment #9
EE 330 Lab | Fridays 1 PM
Joe O’Connor | Onochie Ani | Artin Darabari
Performed on 3/20/2015
Overview:
In experiment 9 we learned about diodes and their applications. We got familiar with the currentvoltage relationships of diodes then we built rectifiers and wave shaping circuits using the diodes. The
purpose of this lab is to understand rectifiers and diodes better.
Steps 1-2:
For these steps we had to build the circuit illustrated in figure 6. We also had to connect the DMMs
properly so that one measures current and the other measures voltage. We then had to measure
current and voltage by varying the power supply from 0 volts to 1 volt in 0.1V steps and 1V to 12V in 1V
steps. Our 1k ohm resistors actual value was 0.9738. Our Measurements for current and voltage are
below: We noticed the value of id exceeds 40uA around 500mV.
Vps
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
2
3
4
5
6
7
8
9
10
11
12
Vd (mV)
0.0437
0.0821
0.174
0.266
0.358
0.379
0.438
0.468
0.486
0.498
0.507
0.526
0.536
0.548
0.552
0.557
0.631
0.645
0.653
0.663
0.674
0.683
Id (mA)
0.316
0.773
0.18
0.27
0.368
0.427
0.538
0.63
0.733
0.819
1.02
2
3.006
4.014
5.053
6.032
7.062
8.093
9.064
10.09
11.082
12.098
Steps 4-5:
For these steps we had to create the circuit under test (fig 7). We then connected the dmm properly and
then measured the voltage across the 10 ohm resistor. We measured voltage from -10v to 10v using
0.2v steps for -1.4v to 1.4v and using 1v steps outside of that range. Our measurements are below. The
slope when v = 0 is very close to 0, and the other slopes (1v, 4v, and 9v) all are very close to 1 (around
0.9).
Vps
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
2
3
4
5
6
7
8
9
10
v
-103.8
-93.7
-83.9
-72.64
-62.33
-51.528
-41.714
-30.15
-20.67
-14.422
-12.73
-10.286
-8.621
-6.521
-4.01
-2.151
0.003
2.391
4.023
6.157
8.48
10.433
12.4
14.627
20.848
31.096
41.6
50.703
61.52
72.502
82.828
93.303
104.186
Step 6:
For this Step we had to replace the power supply with the function generator. We set the function
generator to Hi-Z output, 1kHz sine wave with a 4Vp-p(+ - 2v) and zero offset. We then used the
oscilloscopes channel 1 to monitor the input and channel 2 to monitor v. We then used the scopes
cursor function to manually measure voltage difference between the peak voltages of the function
generator and v. By measuring the voltage drop across the diode between the resistor and function
generator, we found that delta V was around 700mV.
Steps 7-9:
For these steps the only thing we needed to do to the circuit was to add a 0.47uF capacitor in parallel to
the kohm resistor. The value of our capacitor was .487uF. We did the same thing as the previous step
(channel 1 to monitor the input and channel 2 to monitor v). We then hoped to see something like
figure 5. We then used the scopes measure function to automatically obtain AC and DC RMS values of v
(around 2.932v). Then we used the scopes cursor function to manually measure the peak to peak ripple
of v (around 0.52v). Our wave is below, it was indeed similar to figure 5.
Step 10:
For this step, we replaced the 0.47uF capacitor with some between 2 and 5 uF. The one we got was
4.7uF which was easy to find. Then we repeated the same steps as steps 7-9. We got the waveforms
below. We used the scopes measure function to automatically obtain RMS value of 3.05V. Then we used
the cursor function to manually measure the peak to peak ripple of wave form v to be around 0V. The
RMS value of v is not affected that much by the capacitor value. The higher the capacitance the smaller
the ripple voltage becomes. Our waves are below:
Steps 12-14:
For this step we had to build the circuit of figure 10 and then use the triple output power supply for Vin
and the other power supply for Vdc = 1.5V. Then we connected the com of the triple output power
supply to the negative terminal of the other power supply. Then We measured Vout while varying Vin
from -4v to 4v in 0.5 increments. Our measurements are below. Because the diode and Vdc voltages
absorb the power supplied by that voltage which leads directly to ground, when the diode is forward
biased Vin gets larger and Vout goes to 2v. When the diode is reversed biased Vout equals Vin because
the diode acts like an open circuit which means no voltage drop from the resistor. The current flow in
the resistor when the diode is forward biased is the diode current because the resistor and diode are in
series.
Step 15:
With Vin from figure 10 attached to the Function generator, we set the function generator for Hi-Z
output, 1kHz sine wave, 0V offset and 8Vp-p (+ -4Vpeak). Then we set Vdc at 1.5v. We then used the
scopes channel 1 to monitor Vin and channel 2 to monitor Vout. We then set the scope for DC coupling
and adjusted the ground voltages of channel 1 and channel 2 to center of the oscilloscope. Then we
used the scopes cursor function to measure Voutmax to equal around 1.5-1.6V and Voutmin to equal
around -8.2-8.3V. Our wave form is below.
Step 16:
This final step used the same set up as the previous step but we had to repeat the measurements with
Vdc to equal 0.5V and 2.5V. For 0.5v, We got Voutmax to be around .75V and Voutmin to be around -8v.
For 2.5v we got Voutmax to equal around 2.5v and Voutmin to be around -8.5v. Vdc effects Vout
because Vdc sets a voltage limit on how much voltage at the positive signal can go through the diode.
When Vdc goes up the sine wave signal limit goes up. Same for the negative current direction. The
diode acts as an open circuit at all times because the negative current can’t go through the circuit. Our
waveforms are below: