EE4012 - Lab 2A
Ciarn O Mara - Student ID: 15154394
Lab purpose
1. Installation of circuit simulator Simetrix.
2. Download the user manual.
3. Schematic entry and DC simulation.
Procedure
1. Download the Simetrix circuit simulator from their website.
2. Download the user manual from their website.
3. Follow the lab PDF to draw and configure the schematic.
4. Configure the simulator to DCOP.
5. Display Bias information for R2 and observe it in the command shell.
Circuit Analysis
The circuit was entered configured and simulated on Simetrix.
In this circuit the voltages are displayed at the two nodes respectively.
The bias information is displayed for R4 also. This gives other information such as
total power dissipation.
In figure 3 the circuit was drawn out. This shows where the results seen in the
simulation come from.
Fig 1. Circuit Schematic (Simulated)
Fig 2. Bias Info
Conclusion
The results generated by the simulation were as expected and based on the analysis
calculations its clear where they come from.
The schematic was very easily entered into Simetrix and there were no problems
encountered when doing so, configuring or simulating.
Fig 3. Circuit analysis calculations
Module: EE4012 Circuit Analysis 1
Lab: 2
Student name: Ciarn O Mara
Student ID: 15154394
Lab Purpose
1.) Prototype a simple resistive circuit
2.) Carry out DC measurements
3.) Correlate measurement results simulation (Lab 1)
Part(i) Circuit and Resistor Tolerance
Lab Summary / Procedure
Measure the actual resistance of the resistors you are going to use using an ohmmeter and calculate
their tolerance using by taking the expected voltage away from the actual voltage and dividing by the
expected voltage.
Set up the circuit as shown in the diagram with two 1K resistors, two 10K resistors and a 3.3K resistor.
Connect up the two power supplies calibrated to 5v and 12V and the voltmeter at the relevant nodes
A and B and compare the readings to the results generated in the simulation on Simetrx.
Take the results down in a table. Then take further readings from Vb while changing the second
voltage from 8V to 12V in increments of 1V.
Finally use simultaneous equations to solve for the two constants in the equation of the relationship
of Vb and V2.
Expected Resistor Values
Measured Values
Tolerance % Tolerance
R1 1K 985ohm - 0.015 - 1.5%
R2 1k 988ohm - 0.012 - 1.2%
R3 3.3K 3.28K - 0.0006 - 0.06%
R4 10K 9.9K - 0.01 - 1%
R5 10K 9.9K - 0.01 - 1%
Margins of error (Va and Vb) due to the tolerance in the resistors
The percentage that we saw in when comparing our lab results to the theoretical simulation result
was virtually 0%. This was probably due to the fact that we only took readings correct to two decimal
places so they were rounded and appeared the same as the simulation results.
When the actual lab environment was simulated i.e. when the theoretical resistor values were
replaced with the actual resistance that was measured in the lab a small percentage error was
observed in the difference between Va and Vb
Part (ii) Investigating relationship between voltages at Vband V2
Its clear based on the graph below that theres a
linear relationship between Vb and V2. The slope
of the line based on the equation above is 0.22.
This means that for every volt you add the the
power source the voltage at node b will increase
by 0.22. The y-intercept is also obvious from the
equation being at 1.38V, meaning that when V2 is
0V there will still be a voltage of 1.38V at node due
to V1.
Simulation (expected R) Lab (actual R) Margin of error
Va = 2.69886V Va = 2.69V ~ 0%
Vb = 4.01136V Vb = 4.01V ~ 0%
Simulation (expected R) Simulation (actual R) Margin of error
Va = 2.69886V Va = 2.70149V ~ 0.09744%
Vb = 4.01136V Vb = 4.01609V ~ 0.1179%
Voltage Supply Voltage at B
8V 3.14V
8.5V 3.25V
9V 3.36V
9.5V 3.47V
10V 3.58V
10.5V 3.68V
11V 3.79V
11.5V 3.9V
12V 4.01V
Fig 1. Simulation (expected R) Fig 1. Simulation (actual R)
These are both an experimental graph,
created in Matlab from the lab results
and the theoretical graph that was
created in Simetrix laid on top of each
other to scale. It is evident that they
virtually have the same slope. This is
further evidence that shows for this
particular circuit the tolerance of the
resistors had virtually no effect on
readings while also showing that the
values calculated for m and n are very
accurate.
m and n are calculated simply with the use of simultaneous equations. Vb from two
voltages (8V and 9V) were subbed in and
manipulated so as first n could be calculated
and then m. The answers for both m and n
were subbed back into the theoretical results
from Simetrix to check if the answers
calculated were correct. The answers could
also be checked by calculating the slope and
y-intercept of the theoretical graph
Conclusion, Comments and Analysis
The tolerances measured for the resistors were very small and well inside the 10% tolerance
limit.
The measured voltages at nodes A and B were virtually the same as those from those seen in
the simulation. They had a 0% error but this was mostly down to the fact that
measurements in the lab were taken to two significant figures.
Any margins of error could be explained by looking at the tolerances of the resistors, the
accuracy of the voltmeter, or even the smalls resistances due to the jumper wires.
Vb = mV2 + n
1.) 7.14 = 8m + n
2.) 3.36 = 9m + n
3.14=8(0.22) +
n
n = 1.38
3.14 =8m + 3.36 -9m
-0.22 = -1m
m = 0.22
Check for 12V
4.01 = 12(.022) + 1.38
4.01 ~ 4.02
Fig 3. F(x)=0.22x+1.38 plotted in
Matlab and Simetrix on top of each
other
There is a linear relationship between Vb and V2 which is observed in the results, graph and
in the calculation and the check. The two constants being the slope (m) and the y-intercept
(n) of the graph
Fig 4. Pictures of the circuit voltage
supply and voltmeter
Module: Circuit Analysis 1 EE4012
Lab: 3
Student name: Ciarn O Mara
Student ID: 15154394
Lab Purpose:
Design and optimisation of a voltage circuit
Resistor E series (12). Parallel connection
Use voltmeter and ohmmeter
Lab Procedure:
Calculate the two resistor values that when placed in series will create a voltage
divider that will divide 5V down to 3.3V from the list of E12 resistors.
Take the two chosen resistors from the box and measure their resistance using the
ohmmeter.
Set the power supply to supply 5V to the digital designer bread board.
Connect the two resistors in series from 5V to ground and the voltmeter from node a
as shown in the diagram to ground.
Take note of the reading from the voltmeter, then calculate how you could improve
the accuracy of the result by including resistors in parallel.
Take note of this new and more accurate reading and continue to calculate the
percentage error in the result using the tolerances of the resistors.
E12 Resistors {1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3,9, 4.7, 5.6, 6.8, 8.2}
Fig 1. Simple Voltage Divider Circuit
Lab Summary
Design and build the circuit
The circuit was built using two separate sets of resistors to
see which two would generate an answer closest to the 3.3V
required.
The ideal resistors values for the circuit would be a 3.4K and
a 6.6K however these resistors are not an element of the E12
set.
Therefore, a 3.3K resistor was placed in series with a 6.8K
resistor. The voltage reading node A with these two values of
resistors was 3.355V, (percentage error 1.67%)
(5V)(6.8/3.3+6.8) = 3.3663V
The inaccuracy is as a result of the tolerance of the resistors.
Improve the circuit
The second part required a second resistor in parallel with one of the resistors to
increase the accuracy of the voltage divider.
After various calculations it appeared as though a 120K resistor in parallel with the
6.8K.
The calculated resistor need was ~110K however the
closest value resistor that was available from the E12 set of
resistors was 120K.
Parallel = (6.8*120)/(6.8+120)
(5V)(Parallel/(Parallel+3.3)) = 3.305V
Fig 2. Simetrix Simulation 1
Fig 3. Simetrix Simulation 2
Resistor Tolerances
The expected tolerance of an E12 resistor is said to be 10%. The measured resistance of the
resistors used in the lab were well inside the 10% tolerance allowance which means that
differences in both theoretical and experimental results should be minimal.
Results
The first set of calculations with the 3.3K and 6.8K resistors had a 2% percentage error
theoretically. When the experimental results were analysed it became clear that there was a
1.6% percentage error. The decrease in margin error is down to the resistors tolerance.
When a 1