Transistor Switching

Introduction: The purpose of this lab is to learn about transistors and how to use them.

Procedure: 
Step 1: First we model the following circuit with the proper resistors, led and etc.

Step 2: Assemble the breadboard. 

 

Step 3: Here we are turning on the switch from on to off by connecting them with our fingers. 

 

 Step 4:  The last circuit below was tested using a potentiometer to change the current entering the base while data was connected using two ammeters.

 

Step 5: Record the data.

FreeMat Lab

Introduction: The objective of this lab is to learn the basic functions of FreeMat to solve systems of linear equations by matrix operations and more. 

Procedure:

Step 1: Graph 2 sinusoidal functions on the same graph.

Graph of sine and cosine on the same graph

Step 2: Solve the circuit in the manual.

Here is the solution

Step 3: Plotting Exponentials
Assignment 1: Graph Circuits A and B with the output of 2e^(-t/t_c).
t_c of A is 100 ms, and t_c of B is 200 ms.

Step 4:
Assignment 2: Graph Circuits A and B now have an output of 2(1-e^(-t/t_c)). t_c of A is 100 ms, and t_c of B is 200 ms.

Step 5:
Assignment 2-1 Graph the functions 3sin(2t + 10°), 5cos(2t - 30°) and their function added together.

Next we make it into a script.



 This is what we get below.

Voltage Dividers

Introduction: Sometimes electrical systems will have multiple loads on them, and we need these electrical systems to be able to handle these loads. In this lab we will test out what kind of loads are possible on a circuit of this configuration.

This is "equivalent" of the circuit we will be assembling.

Step 1: Do the calculations

Step 2: Measure components.

Here are the actual ratings for the 3 1k resistors

More information

Step 3: Build the circuit on the breadboard.

This is a picture of us assembling the circuit.

The complete circuit.

Step 4: Take measurements of Req, Vbus, Ibus, and calculate Pload.

Us writing down measurements of Req,Vbus, and Ibus.

Data Table for this lab

Questions:
a. 2 Load calculation: P = VI = (11.58 mA)*(5.78 V) = 66.9 mW

b.

Load	Voltage (V)	Variation (%)
1 Load	6.07	-8.42
2 Load	5.78	-15.02
3 Load	5.52	-24.59

The voltages are not within 5% due to the unregulated power supply. Originally the power supply was measured to be 6.00 V. If the load increases, V changes which changes the values for VBus.

c. V_Bus,min = R_eq*V_s/(R_s + R_eq).
New R_eq = 1/4 kΩ.
V_s = 6.07 V,
R_s = 43.5 Ω
V_Bus,min = 5.52 V
The new variation using V_s = 6V would be -9.92 %.

d. Variation by 1% = 5.94 V < V_s < 6.06 V
V_s = 6.10 V
R_s = 10.3 Ω

Introduction to Biasing

Introduction: In this experiment we use two LED components, each are rated at different voltages and currents. We need to find the appropriate resistors and be able to know what real life capabilities are compared to theory. 

Step 1: First we modeled the system with laboratory equipment.

Step 2: We then calculated the theoretical values for the experiment. The two resistor values are shown above.

My group, doing the all the necessary calculations to do the lab.

The collection of data after calculation and written onto the lab handout.

 Q1: Determine the closest commercially available values for R1 and R2.
The closest values for R1 that we can obtain is 220ohms and for R2 is 420ohms. It would be better to go over the amount of resistance to not burn out the two LEDS.

Step 3: Then we measured the resistors, voltage, and current to ensure we have the right values  before assembling the circuit 

Step 4: Building the circuit on the breadboard. Eureka the LEDS work!

Step 5: Using the DMM to find out all the currents and voltages through each loop.

Step 6: Record all the values into a table, like the one below.

a. A 9V Alkaline battery has 0.2A-hr of current.
I_Supply = 33.6 mA
t = 0.2/I_Supply = 5.95 hr

b. Percent Error
LED1 (Yellow) = 40.32%
LED2 (Green) = 23.65%
Resistors are limited to only certain values in real life; different resistors must be used sometimes.

c. P_out = (14.06 mA)*(6.14 V) + (18.59 mA)*(2.14 V) = 114.8 mW
P_in = (33.6 mA)*(9.26 V) = 246.86 mW
Efficiency = P_out/P_in*100% = 36.3%

d. The efficiency would go up because having less power will be going through the resistors.
For the best efficiency, it would be to set the power supply to 5V

Introduction to DC Circuits

Pictures will be uploaded soon

Introduction: 

This lab is done in order to represent real life scenario in which equipment may have to be tethered anywhere from hundreds to thousands of feet.  In this lab we have to create a circuit with a battery and a load. We will run multiple tests to the circuit and determine what problems can arise. 

 

Steps: 

Given Assumptions

• A "Load" is rated to consume .144w when supplied 12V

• A miminimum load of 11V is required

• Constant battery voltage of 12V(approx) with a capacity of 0.8Ahr

Firstly, the theoretical value of resistance must be calculated.  

R=V^2/P               R=12^2/.144           R=1000ohms 

We then set up the experiment, connecting the equipment into a series and using a DMM for the readings as shown in the diagram. We set the power supply to 12V, and slowly increasing the resistance on the resistance box until the voltage drops to 11V, which will determine the max permissible cable resistance in the wire. 

Next, measure components 

Components      Nominal Value      Measured Value     Within Tolerance     Wattage

Power Supply          12V                12.09V                         Yes           1/8watt

RLoad                     1000ohm         985ohm                        No(1%)           1watt    

Next we performed the experiment

Measurement:

VLoad = 11V

IBatt = 12.1mA

RCableTot = 98Ohm

Data Calculations:

a)Amp - hr = amps x time

  .8 = .0121 x t

  t = 66.66 hrs

b)P = (I^2)R     

  Pcable = (.0121^2)(98) = .0143Watt    

  Pload = (.0121^2)(985) = .144Watt

   Efficiency = (Pout)/(Pout + Plost)100 = (.144)/(.144+.0143)100 = 90.96% efficient

c) Are we exceeding the limits of the resitor box? No

d) Given that the resistance of AWG#30 wire is 0.3451Ω/m, determine the maximum distance between the battery and the load. 

The total length of the wire came out to be 283.97 meters, but usable distance is 142 meters.

e) In the case of the robo-sub project running #28 wire with a 60 foot tether at 20mA 5V. The minimum power required to run the application is 2.6V and 5V is the max the wire can handle.

5V-2.6V = 2.4V left for the wire

V=IR        2.4 = .02(R)     R=120 Ohms
120Ohms * 1foot/.0764ohms = 1570.68 feet maximum for the wire length

f) We are sending 48 volts at 10amps but need at least 36 volts to the sub. So a maximum of 12 Volts can be lost but still safe for regulation.

12V = 10R     R=1.2 ohms

1.2ohms/60ft = .02 ohm/foot minimum

Therefore a minimum of 22 Awg is required.