Capacitor and Inductor Voltage-current Relations

Capacitor and Voltage-current Relations
Using different voltage sources(sine and triangular). We will measure that voltage across the capacitor Vc and the current passing through it ic.

Pre-lab:
Before starting the lab we draw prediction of how Vc will look like .

 

Lab:
First we apply a sinusoidal input voltage with frequency=1kHz, amplitude=2V, and offset=0V, then we used the oscilloscope to see that graph of Vc(yellow) and ic(red). 

Second we apply a sinusoidal input voltage with frequency=2kHz, amplitude=2V, and offset=0V, then we used the oscilloscope to see that graph of Vc(yellow) and ic(red). 

Third we apply triangular input voltage with frequency=100Hz, amplitude=4V, and offset=0V, then we used the oscilloscope to see that graph of Vc(yellow) and ic(red).  

Circuit Setup:

Inductor Voltage-current Relations
 Using different voltage sources(sine and triangular). We will measure that voltage across the inductor VL and the current passing through it iL. 

Lab:
Using the same bread boar and only changing the capacitor to inductor(100mH). We apply a sinusoidal input voltage with frequency=1kHz, amplitude=2V, and offset=0V and plotted a graph using oscilloscope.

  
frequency=2kHz, amplitude=2V, and offset=0V

Circuit Setup:

Passive RC Circuit Natural Response

Using simple RC circuit we examined its natural response by using two different voltage sources(DC and square wave).

Pre-lab:
We calculated the time values for a and b.
a.) t=0.0352s
b.) t=0.242s

Lab:
First we measured the actual values of the resistors.
R1=0.98KOhms
R2=2.15KOhms

Then we apply a 5V source to the circuit. Then we open the oscilloscope to record the data. during the data collection we unplug the voltage source, and we got a graph. From the graph we got the value of  discharge time=361.6ms. Comparing the two values experimental and theoretical we got a percent error of 2.68%. Since the percent error is fairly low I think the measured values are acceptable.

Using a square wave with amplitude of 2.5V and a n offset of 2.5V to supply the circuit. Then we used oscilloscope record the graph of charge and discharge. The time it takes to charge is 68.23ms and the time it takes to discharge is 75.29ms.

 Circuit Setup:

Summing and Difference Amplifier

Summing Amplifier

 In this experiment we created a simple summing amplifier with two voltages.

Pre- Lab:

First we choose a value of the resistor that greater than 1KOhms. The value for all the resistor we choose is 4.7KOhms.  

Lab:

The actual measured values for the Resistor are R1=4.63KOhms, R2=4.66KOhms and R3=4.62KOhms.

We also checked if the analog is working. First we checked wavegen channel 1(Va) and channel 2(Vb). The measured value for the first value for Va=-3.97V and Vb=0.98V. We also checked if the scope(V+ and V-) is working.

Circuit Setup:

After setting up the circuit, we test our design by measuring the values of the output voltage in different values of Va(listed below) and a constant value of Vb(1V).

Sample Vo measurement:

Using the formula Vo = - R3(Va+Vb)/R1, we can compare that values we measure and the theoretical values of Vo. Since R1=R3 we can say that Vo=-(Va+Vb). Looking at the values of Vo we can say that setup of the circuit is right.

 Difference Amplifier
 In this experiment we created a simple difference amplifier with two voltages.


Pre-Lab:
In the pre-lab we determine the relationship Va, Vb and Vo.
Vo=-2(Va-Vb)
The actual values of the resistors are also listed below. 

Lab:
We used the same setup of analog discovery as the summing amplifier. The values of of Va and Vb for part 1 and 2 are listed below, and we measured the values of Vo.

Circuit Setup:

The measured values of Vo in part 1 and 2 are acceptable since Vo=-2(Va-Vb) and Vo must be between +5V and -5V.

Inverting Voltage Amplifier

Prelab:

Before the lab we determine what values of the resistor we need to have a gain of 2.

Lab:

First we got the actual values of the resistor

R1 = 2.15Kohms

R2 =  4.62Kohms

We use red and white wire from scope to provide the V+ and V- which are +5 and -5. We also connected the an input voltage that started from -3V to 4V with an increment of 0.5V. Then, using the DMM we measured the output voltage and recorded the values.
 Setup:

Sample Data:

Data and Chart:

Circuit Gain = - R2/R1
Circuit Gain = - 4.7/2.2
Circuit Gain = - 2.136

Using the measured and expected circuit gain, we calculated the percent error of  the circuit gain and the value we got is 0.468%. The percent error we calculated is fairly small so the measured value are acceptable.

Matlab

Solving Simultaneous Equation

Dependent Source and MOSFETs

In the experiment we setup VCCS and tested the results.

Lab:

We setup the circuit in the bread board and connected the analog box.

Using wavegen we supplied voltage from 0 to 5V, and we measured the current.

We repeated the step 9 more times, and plotted a graph of Voltage vs Current.

Looking at the chart the threshold voltage of the MOSFET is around 36.1V. The MOSFET is behaving like a dependent source. Since as we change the value of the voltage the current also changes. Using the plot we created a line of fit to get the slope the line which is the value of  g.

g = 10.124

Mesh Analyis 2

In this experiment we predicted the values for voltage and current using mesh analysis. 

Prelab:
Using mesh analysis we calculated the value of current and voltage in the circuit.

i1 = 5.56E-05A

i2 = -0.00032A

i3 = -0.00106A

I1= -0.00032A

i = i2 - i3

i = -0.00032A - -0.00106A       

i = 7.4E-4A

V1 = iR

V1 = 7.4E-4A(6800ohms)

V1 = 5.032V

Lab:
We first measured the resistance of the different resistor we are using.

Circuit setup

Current and Voltage value measure.

Percent error between measured and expected values of V1 and I1. The voltage values are acceptable but the value for current has a large percent error.

Temperature Measurement System

This experiment used a thermistor that change resistance with the temperature.

Prelab:
We first calculated the values of R for the temperature between 25°C and 37°C,and voltage out(Vout) value increases by a minimum of 0.5V. The value calculated for R is between 5727ohms to 9000ohms. The resistor that we have in the lab that is between the calculated value is 8200ohms.

From the graph Temperature vs Resistance:

11000ohms @ 25°C

7000ohms @ 37°C

Lab:

First check the resistance value of the given resistor. R = 7.98Kohms

We also check if the thermistor is working by changing its temperature from room temperature to normal body temperature. The value of thermistor's resistance is inversely proportional to temperature.

The bread board setup

Then we measured the voltage in room temperature to normal body temperature.

Intial Voltage - 2.18V

Final Voltage - 2.74V

Output Voltage increase - 0.58V

The Output voltage is close to the desire value of 0.5V over the temperature range of 25 to 37 degree C.

Percent Error 

Video Clip: