Sunday, February 12, 2017

Week 5 Lab

1. Functional check: Oscilloscope manual page 5. Perform the functional check (photo). 
Picture 1.1 shows the functional check for the 1st port on the oscilloscope
Picture 1.2 shows the functional check for the second port. 

2. Perform manual probe compensation (Oscilloscope manual page 8) (Photo of overcompensation and proper compensation). 
Picture 2.1 shows a functional check when the probe is overcompensation

Picture 2.2 shows a functional check when the probe is proper compensation

3. What does probe attenuation (1x vs 10x) do (Oscilloscope manual page 9)? 

Using 1x on the porobe limits the bandwidth to 7MHz where 10x uses the full bandwidth. The 10x also reduces the amplitude of the signal 10x more than 1x probe. The 10x also does not disrupt the circuit reading as much as the 1x which can change the waveform readings. The 1x probe is only better for reading low voltage measurements. 
4. How do vertical and horizontal controls work? Why would you need it (Oscilloscope manual pages 34-35)? 

By using vertical positioning knobs for graph one you can change where the displays on the y axis by moving up and down on the y axis. Using the horizontal knobs changes the view of the display left and right down the x axis. These allows us to shift the waveform on the display to get more accurate reading and to compare it to other waveforms.  

5. Generate a 1 kHz, 0.5 Vpp around a DC 1 V from the function generator (use the output connector). DO NOT USE oscilloscope probes for the function generator. There is a separate BNC cable for the function generator. 

a. Connect this to the oscilloscope and verify the input signal using the horizontal and vertical readings (photo). 
Picture5.1: shows the input signal using horizontal and vertical readings 
We generated a voltage of 560mV peak to peak on the osiclloscope by using the function generator.  By generating 0.25Vp and 1 KHz using the function generator.

b. Figure out how to measure the signal properties using menu buttons on the scope. 

By using the measure button on the oscilloscope which is located above the vertical adjustment nobs and to the left of the auto set button. Then on the display on the right of the screen you can use the buttons for each slots to change the variable the oscilloscope will measure and what channel it will measure from.  

Picture5.2 shows where the button is located 

6. Connect function generator and oscilloscope probes switched (red to black, black to red). What happens? Why? 

When we switch the connection between the probes of the function generator black and red with the probes of the oscilloscope the oscilloscope does not read anything because if we connect the red probe of the function generator to the clip of the oscilloscope the values sent from the function generator is sent to ground since the clip is the ground. 

7. After calibrating the second probe, implement the voltage divider circuit below (UPDATE! V2 should be 0.5Vac and 2Vdc). Measure the following voltages using the Oscilloscope and comment on your results: 

a. Va and Vb at the same time (Photo) 
Picture7.1:show  signal of Va and Vb  after measuring from the oscilloscope
  The first channel measured a small value which was 1 V and the second channel measures a bigger value which was 2V. 

b. Voltage across R4. 


Since the the measurement of Vb is measurement of voltage across R4 and R5, and the measurement of Va is the measurement of voltage across R5. So Vb-Va should be the measurement of voltage across R4.
AC= 0.118V
DC= 1.337V

8. For the same circuit above, measure Va and Vb using the handheld DMM both in AC and DC mode. What are your findings? Explain. 
Table 8.1 shows the values obtain from measuring Va &Vb using the DMM in AC & DC modes. 
Since the the 5V DC should be equally spread across the resistor which should be a DC value of 1.67V across each resistors. Va is a measurement of just one resistor so it should be close to that value which we got 1.335V and the measurement across Vb is two resistors which should be 3.406V or just double the measurement of Va so using our value of Va Vb should be 6.670V we got 2.672V.

9. For the circuit below 
a. Calculate R so given voltage values are satisfied. Explain your work (video) 

Video9.1: show how we found R7

b. Construct the circuit and measure the values with the DMM and oscilloscope (video). Hint: 1kΩ cannot be probed directly by the scope. But R6 and R7 are in series and it does not matter which one is connected to the function generator. 

Video9.2: measuring resistance 

Video9.3: measuring resistance 

10. Operational amplifier basics: Construct the following circuits using the pin diagram of the opamp. The half circle on top of the pin diagram corresponds to the notch on the integrated circuit (IC). Explanations of the pin numbers are below: 

a. Inverting amplifier: Rin = 1kΩ, Rf = 5kΩ (do not forget -10 V and +10 V). Apply 1 Vpp @ 1kHz. Observe input and output at the same time. What happens if you slowly increase the input voltage up to 5 V? Explain your findings. (Video) 

  Video10.1: Explain what happens when we increase the voltage 

of the voltage when we increase the voltage of the input in an inverting amplifier.

When the input value(in Blue) increases from 0.5V to 5 V, The peak to peak value will increases until it reaches its maximum value which was in our video 9.5 Vpp and then the wave of the output  will round out. In our experiment we tried to increase the voltage of the input but the output value wouldn't change and Output voltage would read 5 Vrms.  

b. Non-inverting amplifier: R1 = 1kΩ, R2 = 5kΩ (do not forget -10 V and +10 V). Apply 1 Vpp @ 1kHz. Observe input and output at the same time. What happens if you slowly increase the input voltage up to 5 V? Explain your findings. (Video)
                                                            Video10.2: Explain what happens when we increase the voltage                                                            
    of the voltage when we increase the voltage of the input in a

Non-inverting amplifier.

it is like the inverted amplifier but in the non-inverted amplifier , the input voltage and the output voltage starts close to each other when the value is small but as the voltage increases, the output voltage increase greater and it is because the gain is higher. Until the maximum value is reached which is 9.6V, then it would round out and no matter how we increase the input value, the output voltage willn't increase.


  1. I found that most answers similar to our answers.
    In Q6, also the function generator will be sorted.

  2. Captions are not there in most of the photos and videos. It is a bit hard for me to see the photos you are standing a little far maybe. but as I can see question #1 is almost the same we have. For question #5 and #7 there is a big difference. I guess you have not done question #9 part A yet. Other than that great explanation and clear videos.
    Well done.

  3. good job this week. we had the same reasoning for the answer for number 6 and most of our numbers also were quite similar. for number 2 however, we didn't have to calibrate our probe as it was already calibrated so its interesting to see what it looks like when it isn't.

    1. It is great. That means our measurements are accurate, thanks

  4. You had a pretty good blog this week. Other than adding an explanation to most of the questions, the explanations you guys have are pretty full and well explained. We also had a similar answer for number 6.

    1. Thanks for your comment, it was really helpful