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