Please help me with my lab report

EECE 315, Lab Report (SAMPLE)

Number (i.e. Lab 01) Pre / Class

Name FINAL LAB REPORT SAMPLE

Student ID

Date Wed / Fri

Collaborators No Collaborators

Testing of Vγ Introduction:

In this laboratory experiment, we are testing the turn-on voltage, Vγ of a diode. Using

Pspice, we will map out our circuit for analysis. The circuit is a simple one with a DC voltage

source, a varying resistor (ranged between 2,000-14,000 Ω).

For our pre-lab, we predicted what turn-on voltage we were expecting for the diode,

while varying both the voltage source, and the resistor. From our findings, we plotted in Excell

the results for VD and ID. We plotted our results against a semi-lograthmic scale. By doing this,

it enables us to view our results as a linear plot, rather than an exponential one.

For the lab portion of our experiment, our task is to measure the i-v characteristics of a

1N4148 diode. We will be creating a physical circuit of the pre-lab using the lab kits provided

for our use. On the breadboard, we constructed the simple circuit using the resistance we

selected from our Pre-lab. From this circuit, we analyzed the board using the digital

multimeter.

Circle one

Apparatus Diagram:

For the Pre-lab, we drafted the following schematic in Pspice:

Experiment Procedure:

Our Pre-lab procedure was all done digitally with the computing platform Pspice. Once

we got to lab, we first needed to set up all of our equipment properly so that we don’t have any

problems during our testing. First, we had to make sure that the computer was fully booted up

before turning on our oscilloscope and multimeter. This is because you can sync the

oscilloscope output on to the computers using the program Open Choice Desktop. Once this

has been done, we can get a digital output on our computer of all our oscilloscope results.

Our circuit was constructed on a breadboard, and we used a variable resistor for RVR so

that it is easy for us to test the same diode over different resistance values. By trying 2

different values of resistance, we measured (with the multimeter) the voltage drop across both

the diode and the resistor. We kept our results to a minimum precision of 3 significant digits.

Once we had the voltage drop across the resistor, we now know the diode current, ID. We then

adjusted the DC voltage source or the resistance so that we got the correct current, and

tabulated our data on an excel spreadsheet.

Data:

These are the results from

the pre-lab:

This was the data from our lab

results. We plotted our calculated

values of V vs I against our

theoretical values of a perfect-case

scenario which we calculate from the pre-lab:

Collaborators:

Discussion:

After getting our results, we used our values for the voltage drop across the diode, VD,

while keeping our resistance and power source voltage up to date with the required values

from our table from our pre-lab. We were running into some discrepancies with a few rows of

our data, where our predicted values of ID were inconsistent with our experimental results. We

improved our data by taking the voltage drops across the resistor for these situations, and

divided this by the resistance, and our data became more consistent. We finally plotted the

Voltage (VD) with respect to the current (ID) of our diode, and showed how on a logarithmic

scale for current, the voltage needs to be increased only slightly to see a decade-scale eruption

of current.

During our testing, we varied our voltage source from 0V-20V, but while doing this, we

only saw a minimal difference in the voltage drop across the diode. The voltage drop that we

measured ranged only from .7 Volts to .4 Volts.

Conclusion:

From this laboratory experiment, we learned many things about the diode. We tested

the turn-on voltage, Vγ across a range of voltages from .4V to .7V. However, it was at the

miniature scale of voltage range from .6V to .68V that was most interesting to us, and it is here

that we see the current, running through the diode, raise exponentially once Vγ is reached. In

order to see a smooth plot of these results, we plotted the Y scale of our data graph as an

exponential scale of the current, ID. This was a fun lab to do, and taught me much about how

the current gets “turned on” with the diode.