EGR 393 Week 3 Blog

Week 3

1. Compare the calculated and measured equivalent resistance values between the nodes A and B for three circuit configurations given below. Choose your own resistors?

The resistors are: 101  ohm, 47 ohm, 1.2 K ohm, and 47 ohm.

Group	Measured (ohms)	Calculated (ohms)
A	32	31.3
B	146.3	145.6
C	77.5	79.4

 Table 1. Calculated and measured value for resistor combinations

2. Apply 5V on a 120 Ω resistor. Measure the current by putting the multimeter in series and parallel. Why are they different?

 in series we got 39.8 mA, in the parallel we cannot measure the current because the current here is so high, and the resistance is like 0+ and V/0+ gave an infinity.

3. Apply 5 V to two resistors (47 Ω and 120 Ω) that are in series. Compare the measured and calculated values of voltage and current values on each resistor?

Resistor(ohm)	Calculated Voltage(V)	Measured Voltage(V)	Calculated Current(mA)	Measured Current(mA)
47	1.4	1.43	29.94	28.98
120	3.6	3.64	29.94	28.98

 Table 2. Calculated and measured values for 47Ohm and 120Ohm Resistors

The measured and calculated value for voltage and current are so close. The current for both resistors is the same because they are in series.

4. Apply 5 V to two resistors (47 Ω and 120 Ω) that are in parallel. Compare the measured and calculated values of voltage and current values on each resistor?

Resistor(ohm)	Calculated Voltage(V)	Measured Voltage(V)	Calculated Current(mA)	Measured Current(mA)
47	5	5.03	97	90
120	5	5.03	42.23	39.9

table 3. Calculated and measured values for 47Ohm and 120Ohm Resistors

 The measured and calculated value for voltage and current are so close. the voltage across the two resistor are the same because they are in parallel but the current is different.

5. Compare the calculated and measured values of the following current and voltage for the circuit below: (breadboard photo)
a. Current on 2 kΩ resistor.
Measured is 1.94 mA,                       Calculated is 1.9993
b. Voltage across both 1.2 kΩ resistors.
 For R1=1.2kΩ,            Calculated voltage = 0.84V,            Measured voltage = 0.859V.
 For R2=1.2kΩ,           Calculated voltage = 0.689V,           Measured voltage = 0.705V

6. What would be the equivalent resistance value of the circuit above (between the power supply nodes)?
Equiv. Res. = 2520 Ohms

7. Measure the equivalent resistance with and without the 5 V power supply. Are they different? Why?

The equivalent resistance without power is 2.62 k Ohms, and you can't measure it with the power on.  You can't measure the Eq. Re when the power is on because there is a current flowing through the circuit and it'll measure the current or the voltage, but not the resistance.

8. Explain the operation of a potentiometer by measuring the resistance values between the terminals (there are 3 terminals, so there would be 3 combinations). (video)


The potentiometer changes the resistance values when the pins are set in different orders.  The combination of (A/C)/(B/C) had minimum readings, and then (A/B) had the highest reading.

9. What would be the minimum and maximum voltage that can be obtained at V1 by changing the knob position of the 5 KΩ pot? Explain.

The minimum voltage would be 0 Volts and the maximum voltage would be 5 Volts.  0 Volts comes from max resistance and 5 V comes from no resistance.

10. How are V1 and V2 (voltages are defined with respect to ground) related and how do they change with the position of the knob of the pot? (video)

V2 is always lower than V1.  When V1 goes lower, V2 goes lower because it is always in respect to the input voltage of V1.

11. For the circuit below, YOU SHOULD NOT turn down the potentiometer all the way down to reach 0 Ω. Why?

Turning down the potentiometer all the way down to zero acts like you are dividing the voltage by 0+, and will short the circuit because too much current will be flowing through the circuit.

12. For the circuit above, how are current values of 1 kΩ resistor and 5 KΩ pot related and how do they change with the position of the knob of the pot? (video).

When the resistor was 1K Ohm, the current was 5mA, and when the Resistor was 5K Ohm, the current was 1mA.  This is because there are 5 Volts flowing through the circuit, so it needs to be the same with the current/resistance change. It has to add up to 5 Volts.

13. Explain what a voltage divider is and how it works based on your experiments.

A voltage divider turns large voltage into smaller voltage.  Using two resistors in series, the output voltage is much smaller than the input.

14. Explain what a current divider is and how it works based on your experiments.

A current divider creates an output current that is much smaller than the input current.  You use one with two resistors in series.

EGR 393 Week 2 Blog - Drake Csage and Mohammad Ghallab

1. What is the role of A/B switch? If you are on A, would B still give you a voltage?

The A/B switch shows the display of the voltage.  It selects simultaneous current and voltage metering for the A B supplies.  When the position of the switch is in the A position, the meters are connected to the A supply, and same goes with the B position.  If the circuit is still on, then yes the power supply will still give you a voltage.  

2. In each channel, there is a current specification (either 0.5 A or 4 A). What does that mean?

This is the max current that is allowed to flow through each of the channels.  If the red light comes on it means that the circuit has overloaded or is close to overloading and the current or voltage should be lowered.  

3. Your power supply has two main operation modes for A and B channels; independent and tracking. How do those operation work? (Video)

In the independent mode, A and B can be set differently from each other and you can switch between the different voltages.  In the Tracking mode, the voltages track each other and will be the same.  It will be the smallest voltage set between A and B.  

4. Can you generate +30 V using a combination of the power supply outputs? How? (Photo)

Yes.  You can keep the Power Supply on independent, and set both A and B voltages to 15 Volts.  Then connecting them to the Digital Multi meter it will read 30 V.  

5. Can you generate -30 V using a combination of the power supply outputs? How? (Photo)

Yes.  Using the same setup that was used in number 4, switch the clips.  This will change the polarity and make the voltage negative.

6. Can you generate +10 V and -10 V at the same time using a combination of the power supply outputs? How? (Photo)

Yes.  By setting the output to series, and the voltage to a set such as A to 10 Volts, you can generate +10 and -10 just by switching the terminals and changing the polarity.  

7. Apply 5V to a 100 Ω resistor and measure the current by using the DMM. Compare the reading with the current meter reading on the power supply. At what angle of the current knob makes the LED light on? If you keep on decreasing the current limit, what happens to the voltage and current? (Video)

 Using the 82Ω resistor we used Ohm's law to prove that the current for 5 volts was 60.9 mA.  The angle of the current knob that makes the LED light on is 180 degrees from the positive x-axis.  If we keep decreasing the current, the voltage goes down along with the current.  

8. Where is the fuse for the power supply? What is it for?

There are three fuses.  Two fuses are in the front and one is in the back.  The fuse is a safety feature if the current goes higher than it is rated, then the fuse will trip and not allow anymore power to go through.  It will save the machine and not blow the circuits. 

9. Where is the fuse for the DMM? What is it for?

The fuse is in the front.  It is a safety feature that will save the machine and not override the circuits if the current is too high.  

10. What is the difference between 2W and 4W resistor measurements?

The 2W and 4W resistor measurements are all about accuracy.  The 4W is a more accurate measurement because you are measuring the voltage and current at the same time, and not adding the resistance of the W to the resistor.  The 2W adds it's own resistance to the circuit so it will have some sort of % error to it.  .  

11. How would you measure current that is around 10 A using DMM?

On the Digital Multi Meter there is a spot that is 2A max measurement and a spot that is 15A max measurement.  To measure current connect the wires to the 15A max and COM, then break the circuit so it is in series and the current will flow from the circuit to the multi meter and give you your current measurement.  

WEEK 1

Week 1 Blog - Drake Csage and Mohammad Ghallab 


1.     What is the class format?
Monday:.                              Wednesday:                       Friday:              
Quiz discussion                         Lab                                            Blog commenting
Lab introduction                                                                           Blog discussion                      
Lab

Quizzes are worth 45% of the grade, Blogs 30%, Midterms 10%, Final Exam 15% of grade


2.     What are the important safety rules?
• Must know where is the fire extinguisher and first aid kits, and remember telephone and emergency numbers.
• Never touch electrical equipment while standing in a metal floor.
• Ask the instructor if you have questions.
•Power off while not working.

3. Does current kill?

Yes when the amperes is between 0.1 and 0.2 it could cause death. Lower amperes will cause some pain and breathing problems with shock.

4. How do you read color codes? Video

https://www.youtube.com/watch?v=9j4gbLbszio 

5. What is the tolerance? 

The tolerance on the 390 Ohm resistor is 5%.  We know this because the final band color is gold. 

6. Prove all of the resistors are in the tolerance range.

Resistors and Tolerance
390 Ohm	390	G
2200 Ohm	2166	G
270 Ohm	267.2	G
1500 Ohm	1470	G
681 Ohm	682	W
180 Ohm	177	G
2020 Ohm	1980	W
150 Ohm	150	G
2720 Ohm	2700	W
301 Ohm	299	W

Some of the white resistors weren't exactly 0% when we measured, but this could be a glitch with how we read the colors.  For instance, red could have been orange, etc.  

7.Difference between measuring voltage and current using a DMM?

When we measured current we had to break the circuit, and when we measured the voltage we did not.  This is because to measure the current we couldn't allow it to reach the resistor or else a voltage would be measured.  Ohms law - V = iR , so current we had to break the circuit.  

8.  How many different voltages can you get from the power supply?

We can get 3 different voltages at one time.  Two of them with supplies and one with the A and B labels that get go from 0 to 25 volts and can be changed with the turn of the button.  

9. Practice circuit results (video) 

Current Video; 

https://www.youtube.com/watch?v=1MKeVwMW590 

Voltage Video: 

https://www.youtube.com/watch?v=aUOOyLXxW5o 

10. How do you experimentally prove Ohms Law?

To experimentally prove Ohms law, we measured the voltage of the DMM with our handheld multimeters, and then we calculated the current that was going through using the handheld multimeter as well.  Then, we found the resistance using Ohms law.  

82 Ohm Resistor

1 Volt	11.07 mA
2 Volt	20.96 mA
3 Volt	34.17 mA
4 Volt	44.9 mA
5 Volt	56.3 mA

46.5 Ohm Resistor

1 Volt	20.5 mA
2 Volt	38.1 mA
3 Volt	57.1 mA
4 Volt	76.7 mA
5 Volt	91.6 mA

11. Rube Goldberg Video

https://www.youtube.com/watch?v=rn_FwWsQdpo 

12. Draw the Circuit 

Rube Goldberg Circuit Drawing

13.  How to Implement into a Rube Goldberg Machine?

by turning on the light that go to the photo sensor which is connecting to a fan, the the fan is turning on an move the small ball until it hits the ground.