Lab 4 - Transistor Switching

Transistor Switching

Objective:

To understand the schematic of a transistor and its functioning components

Process:

Set up breadboard with 3 resistors, transistor, led, and switch to test behavior of transistor with a finger tap using circuit given.
Elements will be S1: Pushbutton
                         R1: 180 ohms
                         R2: 10k ohms
                         R3: 680 ohms
                         Q1: 2N3904 - transistor
                         D1: Led

Circuit schematic for Finger Switching

Circuit Complete for Finger Switching.

To demonstrate the relationship between the current going through the base and the current emerging from the emitter a new circuit will be built with a potentiometer and two ammeters to showcase both currents.
Elements will be R1:180 ohms
                         R2: 10 ohms
                         R3: 180 ohms
                         P1: 1M linear potentiometer
                         Q1: 2N3904 - transistor

Circuit Schematic for Current Testing

Circuit Complete for Current Testing

Data Collected for A1=I_b and A2=I_e

Data Analyzed in A1 vs A2

Data Calculated - Beta found

Conclusion:

During the first part of the experiment we found just how sensible a transistor can be by touching it and distinguishing the amplified voltage and noticed how bright or dim the led turned. As the experiment progressed  the components that make up  a transistor are the collector, base, and emitter. The transistor essentially amplifies any changes in current applied to the base creating a ratio from incoming current to outgoing. This ratio is called the beta gain and in our experiment yielded the value of 5.93. Unfortunately, range values were not hugh enough to establish a saturation point of when the internal resistance can not go any lower.

Lab 3 - Nodal Analysis

Nodal Analysis

Objectives:

1. Design a split plant operation circuit that would be fail-safe if one of the voltage sources would incur damage in a Typical Power System.
2. Apply nodal analysis to designed circuit using resistors as the load and cables in the System.

Process:

1. Problem
          Assign nodal voltage and establish unknown values of the power supplied by both batteries given the battery voltages, cable resistances, and load resistances. Measure current and voltage to determine validity of circuit analysis using the percent error equation.

2. Given Assumptions
          R_c1 = 100ohms
          R_c2 = R_c3 = 220ohms
          R_L1 = R_L2 = 1000ohms
          V_batt1 = 12volts
          V_batt2 = 9volts

3.Circuit Calculations

4. Built circuit

5. Data Collected

6. Data Analyzed

Conclusion:

In a Typical Power System, multiple voltage sources are used in conjunction with breakers to keep the system viable if one source should happen to get damaged. To emulate this situation an equivalent electrical circuit was given with all breakers closed(image one) and used for analysis fulfilling objective one. Nodal Analysis was performed on the designed circuit which gave V_2 at 10.28volts and V_3 at 8.77volts. Our measurements were near theoretical calculations except both currents were at a high error percentage rate. Possible cause for this is improper use of DMM or location of testing in the circuit.

Lab 2 - Introduction to Biasing

Introduction to Biasing

Objectives:

1. Demonstrate biasing ability by establishing the correct voltage across and current through two LED's so they operate correctly.
2.  Design circuit with use of resistors for biasing and apply KVL and KCL to complete design.

Process:

1. Problem
          Find appropriate values of R_1 and R_2 in given sample circuit schematic for the
LED's to function properly and light up. Measure voltage, current, and resistance to analyze circuit for efficiency and battery discharge.

2. Given Assumptions
          LED_1:  5 volts and 22.75mA
          LED_2:  2 volts and 20mA
          Voltage Source: 9 volts

3. Circuit Calculations

 4. Built Circuit

The LEDS work!

Testing after LED2 was removed from circuit

5. Data Collected

6.Data Analyzed

Conclusion:

Objective one and two were simultaneously met during circuit calculations. The goal was to find an appropriate resister value that would drop the voltage from burning out the LEDS. Those values were 175.82ohms and 350ohms. A crucial lesson learned during this process was that resisters are pre-made at more frequently used values for the market and therefore we could not acquire the necessary ohmage. Instead new resisters of similar value were implemented into the the circuit and caused some discrepancy between our between actual measurement and theoretical calculations yielding a 54.71% error.

Lab 1 - Introduction to dc circuits

Introduction to DC Circuits

Objectives:

1. Become familiarized with lab components and instrumentation equipment for circuit design

2. Design a circuit with unknown resistance load to oblige given constraint variables such as power and voltage.

Process:

1. Problem
          Find resistance in given simple circuit schematic required for it to operate properly with known values. Analyze circuit for distribution efficiency and approximation time before the battery discharges.        

2. Given assumptions
            Power consumed by Voltage load or "load" is 0.144W.
            Load functions at greater than 11V.
            Battery Voltage is constant at 12V(approx) and has a capacity of .8A-hr  

3. Circuit Calculations

     

4. Built Circuit

     

5. Data Collected

     

6. Data Analyzed

     

Conclusion:

         Objective one was met through hands on measurement of the the resistors, voltage source, and current of the circuit built using a Digital Multi-Meter. Classifying the components individually was essential to building the circuit on a breadboard. To find the unknown resistance that the tether could hold was derived through the power equation and came out to be theoretically 1000 ohms. When completed design of the circuit was successful, objective two was achieved. The results configured that it would take 71.81 hours to discharge the battery.