ENGINEERING-43
Load Effect • Thevenín Equivalent
Lab-07
Lab Data Sheet – ENGR-43 Lab-07
Lab Logistics
Experimenter:
Recorder:
Date:
Equipment Used (maker, model, and serial no. if available)
Part-1 Directions – Loading Effects
1. Note that in this and ALL OTHER Laboratory Exercises ENGINEERING UNITS must
accompany ALL Data-Entries and Calculated-Quantities
2. Check out a DMM and Power/Probe Leads for the Power-Supply and DMM
3. Go to the side counter collect resistors, “bread board”, and leads required to construct the
circuit shown in Figure 1.
 When unloaded RL = ; i.e., RL is an Open Circuit.
 See the instructor if the 100-330 kΩ resistors are unavailable
4. Make the Measurements and Calculations needed to complete Table I
© Bruce Mayer, PE • Chabot College • 291199291 • Page 1
Figure 1 • High Drive Current. Vs = 10.00 Vdc. R1 = R2 = 0.8-3.3 kΩ. RL = per Table I
Table I - Hi-Drive Loading Effect
 COLOR-CODED Resistor Values & Tolerances
R1 =
R2 =
 Actual (DMM) Values
Vs =
R1 =
R2 =
RL Nominal
RL Actual
Vout (Calc)
Vout (Meas)
Unloaded
100-330 kΩ
10-33 kΩ
0.8-3.3 kΩ

% = 100x(Vcalc – Vmeas)/Vmeas
© Bruce Mayer, PE • Chabot College • 291199291 • Page 2
Vout %
Part-2 Directions – Loading Effects
5. Modify the previous circuit to the configuration shown in Figure 2 .
 Use the SAME Load Resistors as in part-1.
6. Make the Measurement and Calculations needed to complete Table II.
Figure 2 • Low Drive Current. Vs = 10.00 Vdc. R1 = R2 = 5-11kΩ. RL = per Table II
Table II - Lo-Drive Loading Effect
 COLOR-CODED Resistor Values & Tolerances
R1 =
R2 =
 Actual (DMM) Values
Vs =
R1 =
R2 =
© Bruce Mayer, PE • Chabot College • 291199291 • Page 3
RL Nominal
RL Actual
Vout (Calc)
Vout (Meas)
Vout %
Unloaded
100-330 kΩ
10-33 kΩ
0.8-3.3 kΩ

% = 100x(Vcalc – Vmeas)/Vmeas
Part-3 Directions – Introduction to Thevenín Equivalents
7. Go to the side counter collect resistors, “bread board”, and leads required to construct the
simple “Ladder” circuit shown in Figure 3.
8. Make the Measurements and Calculations needed to complete Table III
 Deactivate a voltage supply by removing its leads and replacing the supply with a short
to GND
 Calculate Vth, Isc, and Rth using the “Actual Values” for Vs, R1, R2 and R3
 Compute the third column of Table III (Vth/Isc) as at the Quotient of columns 1 & 2.
9. Return all lab hardware to the “as-found” condition
Figure 3 • Thevenin Equivalent Circuit. Vs = 9.00 Vdc. R1 = 2.5-4.9 kΩ. R2 = 5.5-8.5 kΩ.
R3 = 0.8-1.8 kΩ.
© Bruce Mayer, PE • Chabot College • 291199291 • Page 4
Table III - V & I DMM Measurements for Figure 3
 COLOR-CODED Resistor Values & Tolerances
R1 =
R2 =
R3 =
 Actual Values Measured by DMM
Vs =
R1 =
R2 =
R3 =
Value
Determination
VTH
ISC
VTH/ISC
RTH
RTH %
Calculated
Measured
%


n/a
RTH % = 100x(RTH – V/I)/(V/I)
%J = 100x(XJ,calc – XJ,meas)/XJ,meas
 Where Xj  one of:
o VTH
o ISC
o VTH/ISC
o RTH
© Bruce Mayer, PE • Chabot College • 291199291 • Page 5
Run Notes/Comments
Print Date/Time = 29-May-16/04:00
© Bruce Mayer, PE • Chabot College • 291199291 • Page 6