DAY 8

In this lab, professor Mason ask us to start it with EveryCircuit.

After we finish the EveryCircuit, we keep it and do the pre-lab in the white board, and check answer with EveryCircuit.

The Thevenin resistance(Rth) is 7.349 k ohm, and the open-circuit voltage(V) is 0.456 V. 

This is a sketch which replaced our Thevenin’s Theorem.

 In this lab, we are going to learn how Thevenin’s Circuit works, and compare to the circuits. 

 First, we measured the theory resistors. Then we set up the board for experiment.

 We measure the voltage on the 4.7 K ohm resistor which is 0.179 V. compare to our theory value 0.175 V. The precent difference is -2.29%. 

 We measure the voltage on the 1 K resistor  resistor which is  0.055 V. compare to our theory value 0.055 V. The precent difference is 0%. 

 Use three resistors to replace the 7.35k ohm resistor.

 We found the Rth is 7.35k ohm, Vl is 0.175V.

Now, we us a potentiometer to replace old resistor. and measured the voltage on the potentiometer.

Experiment set up

 We are going to change resistance in potentiometer , and measure the voltage cross it.

Enter all data into a excel file, and calculate how much power on them(P = V^2 / R)

Use data to make a graph about Power vs. Resistance. In the graph, we see the power almost is a horizontal line, so we can know, the power on the potentiometer should be almost same.

DAY 7

In this lab, we guess what the Vout will be when we have different Vin. 

We guess the shape between Vin and Vout are same, but the amplitude will be different.

In the beginning of the lab, we are going to measure two resistors' true value. 

experiment set up. 

This is a sin wave. The frequency and period are same, but the amplitude is half.

This is a triangular wave. The frequency and period are same, but the amplitude is half. 

This is a square wave.  The frequency and period are same, but the amplitude is half.

In this lab, we are going to learn relationship between the collector current, IC and collector voltage.

  We are going to connect one 100K ohm resistor, one 100 ohm resistor, and a small signal NPN transistor in a breadboard,

Measured one 100 ohm resistor is 99.5 ohm

Measured one 100k ohm resistor is 99.4k ohm

 Experiment set up

The first input wave (top one). 

The second input wave (bot one).

  

The picture shows that oscilloscope of the wave it detected.

We can see that Ic vs Vce have 5 curves.

DAY 6

The purpose of this lab is going to use mesh analysis to calculate the theoretical voltage value which across the 22k ohm resistor, and the current i1 on the top line.

Here is the pre-lab of this experiment. 

In the beginning of the lab, we are going to measure the 4 resistors' real value because they will have some errors

The theory 22k ohm resistor that has a real resistance of 22k ohm.

The theory 1.8k ohm resistor that has a real resistance of 1.7k ohm.

The theory 4.7k ohm resistor that has a real resistance of 4.6k ohm.

The theory 6.8k ohm resistor that has a real resistance of 6.8k ohm.

Experiment set up

The value of V1 and i1 we measure.

The measure value for V1 (2.44V)

The measure value for i1(-0.24 mA) 

In this table, it has all data we have in the lab. The four resistors' theory and real value; the theory and real value for V1 and i1; the precent different for V1 and i1.

In the lab, we have a very close value for theory V1 and real V1(0.97% difference). For the i1, the percent difference is not small, but it is not big, either. (7.69% difference). 

QUIZ 2

We used mesh analysis way to do the group quiz. the work and answer is showed below.

DAY 5

In today's lab, we are going to use nodal analysis to calculate the two voltages at position V1 and position V2. And, compare the theoretical or actual value of voltage.

Per-Lab:

Measure the value of three resistors

After we calculated V1 and V2, we set up the experiment, and we connect it to with waveform as power supply. And connect the three resistors.

Recorded data.:

In the experiment, we recording two voltage data is 2.44V and 4.43V, compare the value from pre-lab 2.424V and 4.424V. their %difference are -0.660% and -0.136%. because our % difference are both less than 1%, our value should be very correct.

quiz one day 4

In the class, we had a quiz. However, when we are doing quiz, we mess up with other knowledge point, so after the classes, we do the quiz again, the answer is showed below.

day 4

  Temperature Measurement System
In this lab, we are going to connect a constant resistor, a changing resistor with temperature, and a constant voltage. And we guess that the changing temperature will affect total resistor. At room temperature, it has 11000 ohm resistance. But when we use hand to touch it, it has 7000 ohm resistance. In order, we change is greater than 0.5. And by calculating  we use theoretical value of  7k ohms at room temperature and 11k ohms as 37 degree.

We should choose a 5.6 k ohm resistor, but its real resistance is 5.49 k ohm.

 The voltage is 5.0 V.

After we set up, at the room temperature, the Vout is 3.38 V

After we warm the resistor with body temperature, the Vout is 2.68 V. 

In the lab we got a voltage is 0.7V; however, our theoretical should be 0.533V. our % difference is -31.3%. I think this problem is caused the by our teammater's hand is highter.

Post lab of this experiment. 

We are asked to design a new circuit and that device must be at least 0.1 V/degree. 

Depending to  our calculation,  it is impossible to get it. The maximum voltage we can get a is 0.563 V in 12 degree’s difference. In fact, Our lab data is bigger than the maximum probably the difference in our temperature is higher than 12 degrees. 

 video about our experiment. 

day 3

1. Cooking Hot Dog.
In the first, Professor Mason prepares a hot dog. And he connect the hot dog with voltage 120 V 
before the experiment, we guess nothing will happen; however the hot dog is going to slowly cooded.

b.) Then, we have three parallel, and two perpendicular LED.
Answer is B.

experiment set up: 

When the hot dog is connected with a voltage 120V, we find that the first and last paralleled LED light is lighting clearly, and other paralleled light up too, Other 2 are stay at the dark.

After looking the LED light up, we find that the hot dog is smoking

Result : When the hot dog is connected with a 120 V, we can know it has current goes though it, so that the LED light up, and hot dog goes to smoke. In the lab, there are only paralleled LED light up because there have different electric potential energy on the two side. But when the LED light is horizontally, there are not light because their two sides are same.

2. Dusk to Dawn Light

The purpose of the lab is going to build a circuit that is light sensitive by connecting a bipolar junction transistor to be a current controller, When we obstruct the light, the different voltage will be calculated. When the it is light, the resistance is 20k, and 1.67V. When it is not light, the resistance is 5k and 3.33V.

  Experience set up:

 When it gets dark(I use my close to obstruct light), the LED light starts to light up. When I move the close back, the LED light gets dark.

 When the LED light do not light up, measure the voltage across the resistor is 1.82V, Its % difference is -8.98.

  When the LED light do light up, measure the voltage of it across the resistor is 2.60V. The % difference is 21.9.

The both big % different is caused by room light, and my close can not apply a grade dark room.