Summer Amplifier (Week 6 - Day 11)

     In this experiment, we analyzed an operational amplifier in order to implement a single mathematical operation: addition. We used this op-amp in order to add voltages from two sources.

     We used both waveform generator channels with v_b set to a constant 1V, and v_a ranging from -4V, -2V, -1V, 0V, 1V, 2V, 3V, 5V. The resistances chosen in this experiment and their measured values are as follows:

R₁ = R₂ = 1kΩ, R₃ = 1.2kΩ
R₁ = 0.995kΩ, R₂ = 0.997kΩ, R₃ = 1.169kΩ

The desired result from this experiment was to measure v_out to be equal to the sum of both voltages.

Complete setup of summing amplifier circuit

Theoretical values using measured resistances along with measured values for v_out:

     There was a discrepancy with some of the theoretical values with the measured ones due to the use of the Digilent product. The Analog Discovery reached saturation at certain input voltages, which we can see from the data collected. Other than that, our actual results came to within about 0.3% - 1.2 % error. This experiment was an overall success. We confirmed that v_out is simply the ratio between the feeder resistor and the other resistors multiplied by their respective voltages.

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(Week 4 - Day 8)

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Time Varying Signals (Week 4 - Day 7)

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Nodal Analysis I (week 2)

Fiesta--Nodal analysis

     Nodal Analysis I:

In this experiment, we analyzed a circuit containing multiple power supplies.

Below is an image of the schematic for our circuit: a +5 volt source, -5 volt source, -3 volt source are connected to a 10 kΩ, 20 kΩ, 6.8 kΩ resistor, respectively.

     One adjustment made in our experiment was the 20 kΩ resistor. We did not have that element available, so we replaced it for a 22 kΩ resistor. 

The following is an image of our circuit set up.

Red = +5 V, White = -5 V, Yellow = -3 V, Black = Ground

     Then, we measured the voltage across the 22 kΩ and 6.8 kΩ resistors.

     Our calculations before actually setting up and testing the circuit...

     

Note: For our V1 we calculated a 0 % error; however, it is more likely that the error was minute. The DMM could only produce a value to the hundredths for our measured voltage, so that was a limiting factor. 

     Overall, the nodal analysis method was successful because the measured values were very close to our predictions.

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Day 6 -- Mesh Analysis Continued (week 3)

In this lab, we continued mesh analysis with the use of two power supplies and various resistors. Our goal was to find the voltage through two circuit elements by first calculating the current flowing through them. We achieved this by method of mesh currents and used our values for i1, i2, and i3, in order to calculate the voltage through the 22 kΩ and 1.8 kΩ resistors. With our predictions, we tested our circuit and proved the accuracy of this method. 

Mesh current values: 

i1 =  0.898 mA

i2 =  -0.112 mA

i3 =  0.260 mA

V1 = (0.112 mA)*(22 kΩ)

      = 2.47 V

Setup of circuit respective to schematic

Measured value of voltage through 22 kΩ resistor

[Insert image of measured voltage through 1.8 kΩ]

Measured voltage through 22 kΩ; V1 = 2.45 V ± 0.005 V

Measured voltage through 1.8kΩ; V2 = [insert]

Expected V1 = 2.47 V

Expected V2 = 0.468 V

Percent differences

[insert]

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Freemat (week 1)

Freemat Exercises:

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Resistance and Ohms Law - Voltage-Current Characteristics (week 1)

Feb 26, 2015

Overview:

     To experiment with a voltage source and resistor, in order to analyze the relationship between voltage, current and resistance.

  Measured resistance: 97.7 ± 0.1 Ω
  
  Display of assembled circuit. The breadboard was used for   
  organization of all the wires.

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Dependent Sources and MOSFETs (week 1)

Overview:
     The purpose of this lab is to use a MOSFET in order to test and analyze a simple voltage controlled current source.

Schematic of circuit:












                       

  

         Experimental Resistance: 97.7  Ω

         MOSFET theshold voltage: 1.45 V

Data:

     Gate-to-Source Voltage vs. Drain Current

     

     

     From our data and plot, we discovered that the drain current can be manipulated with a variable voltage through the gate terminal. This means that the MOSFET behaves as a VCCS because the current through it is dependent on the voltage across it. As we slowly increase the gate voltage, we notice the drain current rise. There was a dramatic rise on our results between voltages of 2.05 and 2.45.

     With the use of Excel, we found the value of g 97.275. The selected points were 2.05 < Vg < 2.45

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