Lab 5

1. Functional Check:  Oscilloscope manual page 5.  Preform the functional check. (Photo)

Functional check for CH1

Functional check for CH2

2.  Preform manual probe compensation (Oscilloscope manual page 8) (Photo of overcompensation and proper compensation)

Photo of overcompensation

Photo of proper compensation

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

When the attenuation switch is set to 1x, the P2200 probe limits the bandwidth of the oscilloscope to 7 MHz.  To use the full bandwidth of the oscilloscope, be sure to set the switch to 10x.

4.  How do the vertical and horizontal controls work?  Why would you need it (Oscilloscope manual page 34-35)?

The vertical controls adjust the height of the wave you see on the screen, and the voltage division control changes the height of the wave smaller or larger so you can fit it on the screen.  The voltage division control does not change the amplitude of the wave, simply how it looks on the screen.

A reason to use the vertical control to adjust the height or position of a wave would be so that you can see the whole wave, centered on whichever axis you deem necessary. 

The horizontal controls slides the waveform left or right.  The seconds division control just changes the amounts of crests and troughs you see on the screen at a time. 

A reason to use the horizontal controls is so you can shift the waveform to an axis of your choosing and so you can zoom in to a specific section so you can measure one period.

5.  Generate a 1kHz, 1Vpp, around a DC 2V 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).  For our measurement, frequency is 1kHz.  We have a 2V peak to peak and an offset of 2V.  To get this we used a amplitude of 1V and an offset of .5V on the signal generator.

A photo of the input signal

              b.  Figure out how to measure the signal properties using the menu buttons on the scope.  We figured out how to measure the signal properties using the menu button.  First you hit the measure button and then you hit one of the buttons on the side of the screen you can choose the source of the signal and you can press the type of value you are looking for such as; frequency, period, mean, RMS, peak to peak, and min/max values.

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

When we connected the oscilloscope probes switched we got an unknown signal on the oscilloscope that was an undefined wave.  The wave resembled the noise form (frequency coming from ground).  This happens because each probes ground is connected to the other probes' output, effectively grounding the source. 

7.  After calibrating the second probe, implement the voltage divider below.  Measure the following voltages using the oscilloscope and comment on your results.  We are using an amplitude of .5V an offset of .25V because that is what the signal generator would output.

a.  Va and Vb at the same time (Photo).  The value that we measured for Vb is 396mV, the value we measured for Va is 212mV.

A photo of Va and Vb being measured at the same time

b.  Voltage across R4.  The voltage we measured across R4 is 212mV.  We can't measure across R4 because the ground of the oscilloscope is a hard ground and it shorts the circuit out.  So to measure R4 we swap it with R5 since it is in series and then measure across R4, which is now at the end of the circuit, to ground. 

8.  For the same circuit above measure Va and Vb with the DMM both in AC and DC mode, explain your findings.

For DC, our Vb measurement is 34.4 mV and Va is 17.5 mV.  For AC, our Vb measurement is 237mV and our Va is 119mV. 

Since we are measuring with the DMM using the function generator we can't measure voltage directly across Va or Vb without shorting the circuit, the only way to measure the resistance of a resistor is to measure the one closest to the ground.  Since all the resistors are the same resistance the voltage drop should be identical for each.  It makes sense that the voltage for Vb is higher than it is for Va because there is more voltage to drop when you short the circuit at Vb than there is when you short the circuit at Va. 

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

    

A video showing the calculation of R

 For R we calculated that the resistance should be 2.5 kiloOhms.

     b.  Construct the circuit and measure the values with the DMM and oscilloscope (video).  Hint:  1kiloOhm 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.

           For R7 we measure that the voltage across the resistor is 5.12V which is nearly the same as the 5.07 that was calculated before.  For R6 we measured 2.2V which is fairly close to the 2V that is shown in the diagram.

A video of us measuring R6 and R7

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

1. DO NOT USE
2. Negative Input
3. Positive Input
4. -10V
5. DO NOT USE
6. Output
7. +10V
8. DO NOT USE

a.  Inverting amplifier: R_in = 1kΩ, R_f = 5kΩ (do not forget -10 V and +10 V). Apply 1 V_pp @ 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)

A video showing our inverted amplifier

b.  Non-inverting amplifier: R₁ = 1kΩ, R₂ = 5kΩ (do not forget -10 V and +10 V). Apply 1 V_pp @ 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)

A video showing our non-inverted amplifier