DC CIRCUITS LAB $3$

$($Superposition Theorem$)$

OBJECTIVES: To solve a network containing two power sources.

To analyze the effect aiding and bucking currents have on circuits. To determine voltage drops across resistors and the polarity of the drops.

MATERIALS: Pos. Power Supply $24$ Vdc Breadboard Digital Multimeter Neg. Power Supply $12$ Vdc Resistors: $820\backslash$Omega $,1$k$\backslash$Omega $,1\mathrm{.}5$k$\backslash$Omega $,2\mathrm{.}2$k$\backslash$Omega

NOTE: On a calculation sheet $($s$)$ show all formulas and all calculations. Record answers and findings on these lab sheets.

PROCEDURES:

I $1.$ Adjust the Positive power supply to $24$ Volts and the Negative power supply to $12$ Volts. Set up the circuit shown below.

$2.$ Measure the voltage at the points indicated and enter them on the schematic.

$3.$ Calculate the voltage drops using any of the techniques you learned and enter them below the schematic. Mark the polarity of each drop and how much drop for each resistor on the schematic.

Calculated Values $($These should match the measured values!$)$:

V$\_($A$)=,$V$\_($B$)=,$

V$\_($R$1)=,$V$\_($R$2)=$

Using the measured values for each resistor, calculate the current through each resistor and show flow direction by an arrow.

R$\_(1)=,$I$\_($A$)=,$I$\_($B$)=$

R$\_(2)=,$I$\_($R$1)=,$

R$\_(4)=,$I$\_($R$2)=,$I$\_($R$4)=$ II $1.$ Now we'll solve the circuit using the Superposition Theoroem. Set up the following circuit. V$\_($B$)$ is removed and replaced it with a short $(0$ ohms$).$ Apply V$\_($A$)$ and repeat as in step

I.

V$\_($A$)=,$V$\_($R$4)=$

V$\_($R$1)=$

V$\_($R$2)=,$

Calculate:

I$\_($A$)=$

I$\_($R$1)=$

I$\_($R$2)=$ III $1.$ In the following circuit V$\_($S$2)$ has been re$-$installed and V$\_($S$1)$ was replaced by a short $(0$ Ohms $).$ Apply V$\_($S$2)$ and repeat as in step II$.$

V$\_($RL$)=$

V$\_($R$2)=$

V$\_($B$)=$

Calculate:

I$\_($RI$)=$

I$\_($R$2)=$ q$,$

V$\_($R$4)=$

I$\_($B$)=$ q$,$

I$\_($R$4)=$

Disconnect power supply and measure resistance across points C and ER$\_($C$-$E$)$ and record. R$\_($C$*$E$)=$

Calculate R$\_($T$)$ and record. R$\_($T$)=$

$3$ IV $1.$ Copy the currents from step $2$ into this schematic. Show direction of

currents by making arrows with dotted lines longrightarrow or $^(*)$ Then copy

the currents from step $3$ into the same schematic showing their direction

by making arrows with dashed lines

or

Observing whether currents are aiding or bucking, mark and label the

resultant amount of current through each resistor in solid lines

or $.$ Mark the total current next to the arrows.

I$\_($R$1)=$

I$\_($R$2)=$

I$\_($R$4)=$

Calculate:

$\{($:$[$V$\_($RI$),]),($V$\_($R$2),=)$:$\},$V$\_($R$4)=$

Do these values agree with the values on the original schematic on page $1?$

$($Hint: They should$)$ Ans

V $1.$ Now treat R$2$ as the Load resistor. Use Thevanins Theorem to find I$\_($R$2).$

Does this value agree with the value from Step IV$?$

$($Hint: It should$)$ Ans.

CONCLUSIONS:

What I learned from this lab: