EGR 101 Resistance Lab • Read this before class on Tuesday
Transcript
Slide 1
EGR 101 Resistance Lab Read this before class on Tuesday
Slide 2
Reminder about Teaming Share the technical load Make sure each
team member understands whats going on
Slide 3
Digital Multimeter (DMM) Used to measure the following: Voltage
DC and AC Current DC and AC Resistance Capacitance Temperature w/
extra probe Also used to check: Diodes Transistors
Slide 4
Today Well Use the DMM to Measure Resistance Resistors restrict
the flow of current, given a fixed voltage Unit = Ohms, They come
in different packages
Slide 5
Color Code The resistors well test today have a color code to
identify their resistance and tolerance.
Slide 6
ColorValueColorValue Black Brown Red Orange Yellow 0123401234
Green Blue Violet Gray White 5678956789 Band 1 (closest to the end)
first digit Band 2 second digit Band 3 power of ten multiplier
(most cases simply the number of zeros) Band 4 tolerance (Red = 2%,
Gold = 5%, Silver = 10%, none = 20%) Resistor Color Band Code
Slide 7
What is Tolerance about? If a resistor has a nominal value of
1000 and a tolerance of 10 % then individual resistors with the
same nominal value are allowed to vary in their actual values from
900 to 1100 and still be considered acceptable. Any resistor
fabricated with an actual value outside that range should be
rejected as not meeting specifications.
Slide 8
Ultimate Goal of this Lab To generate a histogram demonstrating
how many of your resistors meet specifications. A histogram is a
plot that shows how many of an item fall into specific bins.
Slide 9
Example Histogram R#Value 11000 21050 3990 41075 5950 6899
71102 81080 91005 101020 BinFrequency 9001 9501 10002 10503 11002
More1 Raw Data Table Generated by Excel Plot of Excel Table Data
Number of resistors with values < or = to 900 Number of
resistors with values from 1051 through 1100
Slide 10
Practice Problems Brown Blue Red = Yellow Violet Gold = 33 k
Ohms = 1.8 Ohms =
Slide 11
Resistance Lab Part 1 (45 minutes) Each team will be given a
package of resistors. For each resistor, Determine the expected
value of resistance by applying the color code. Measure the actual
value of the resistance by using the ohmmeter function on the
Digital Multimeter. Compare the actual and expected values of
resistance does the actual value fall within the allowable range?
Enter your results in an EXCEL table, as shown on the next
page.
Slide 12
Data for Resistance Lab Part 1 Names:Team # Determined from
color band code Leader:Timekeeper:Recorder: Eg: 450-510 Ohms
100*(Meas-Nom)/Nom
Slide 13
Resistance Lab Part 2 (55 minutes) Each team will be given a
sample of resistors having the same nominal value. For each
resistor: Determine the nominal value from the color code. Measure
and record the resistance of each resistor in the sample. Enter
your data in an Excel table (sheet 2) as shown on the next page.
Plot a histogram bar graph of the measured values and determine the
mean and the standard deviation of the resistance values.
Slide 14
Data for Resistance Lab Part 2 ======
Leader:Timekeeper:Recorder:
Slide 15
Preparing to Plot a Histogram Before you start to generate a
plot, generate a sequence of 5 numbers in your Excel sheet, equally
spaced, from the minimum of your allowable range to the maximum of
your allowable range. For example, if my range was 400-800, I would
generate the following sequence: 400 500 600 700 800
Slide 16
Generating a Histogram Table Click on the Tools pull-down menu
Select Data Analysis (If you dont see Data Analysis, click Mcrosoft
logo, click excel options at the bottom, select Add-Ins and then
select Analysis ToolPak) Select Histogram For Input Range Enter the
cell range with your resistance measurements (e.g. a4:a20) For Bin
Range Enter the cell range of your 5 values For Output Range Enter
the cell that you want to be the upper left corner of your
histogram table
Slide 17
Generating a Histogram Plot Select (click and drag the cursor
over) the table that was created using the histogram command Click
on the Insert pull down menu Select Chart Select Column chart type
(default), click next Youll see a preview of your plot, click next
Enter a label for the x axis and change the plot title from
frequency to something with your nominal resistor value in it,
click next Select as object in sheet 2 in last step then click
finish
Slide 18
What needs to be turned in: Everyone's practice problems A
printout of the data table from the 1 st experiment A printout of
the data table from the 2 nd experiment including: The original
data The histogram table The histogram plot Each participating team
member needs to print and sign his/her name