Blog Report Week 2

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 allows you to read and set the values for the voltage and amperage, you can switch between A and B to see what each of the supplies are putting out on the meters. Suppose you are reading the meters for A, since both of the power supplies are independent from each other, B would still be able to give a voltage.

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

• On the power supply we use there are two types of channels: 1 Fixed, and 2 continuous. On the fixed channel, the current specification is at a constant 4A. As for the continuous independent A/B channels, they can range up to 0.5A each.

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

• This is a video discussing the three different modes of the DC power supply. The first being independent mode and the others being series and parallel versions of the tracking mode.

Video - Different PS Modes

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

• To generate the +30V output, you put the power supply in 

Figure 1: Shows that the tracking mode in series allows you to combine channels A and B to achieve voltages higher than 24 volts, up to 48 volts. 

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

Figure 2: This photo shows that if you switch the probes' polarity from Figure 1, you can achieve negative voltages of up to 48V as well.

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

• It is possible to achieve both negative 10V and positive 10V in the same power supply. This is achieved by connecting channel A and B in series at 10V, then grounding in between the two channels. Measuring from ground across channel B will give -10V and measuring from ground across channel A will give 10V.

Figure 3 (Left) and Figure 4 (Right): Figure 3 shows the voltage measurement at -10V because the probes are measuring from ground to the negative side of channel B. Figure 4 shows a measurement of 10V because the probes are measuring from ground to the positive terminal of channel A.

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?

• This video shows us supplying 5v to the circuit and reducing the current dial on the power supply until the light turns on. This light turns on to indicate that there is an insufficient amount of current to power the circuit to it's full power.

Video - Testing what happens when decreasing current at a rate 

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

• The Fuse for the power supply is located directly underneath the power-cable input-plug on the right side. Technically speaking the fuse is a safety feature, it helps protect the machine and circuits from damage, if too much current is supplied. In a situation where there is too much current, the fuse would blow and need a replacement to allow the power supply to operate again.

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

• The fuse's holder housing for the DMM is located on the back bottom-left panel, it is used to protect the circuits inside of the machine along with the user if too much current were supplied at once.

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

• The two wire and four wire methods are used to measure resistance more accurately. When measuring a resistor that is large, 1 kilohm or higher, the resistance of the two wire method does not make much of a difference. When measuring smaller resistors, 1 kilohm or smaller, the voltage drop across the probes of the multimeter can make a noticeable difference in your values. The four wire method allows the multimeter to push voltage through one wire and current through the other so there is no voltage drop across the probes.

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

• If we were asked to measure a current around 10A, the DMM would require the user to manually set the current range measurement to range up to 12A (AC or DC).

Blog Report Week 1

1.  The class format is:

Monday:                                           Wednesday:                                  Friday:
- Quiz discussions                           - Lab                                             - Blog commenting
- Lab introduction                             - Wrap-Up                                      - Blog discussions
- Lab                                                                                                              
- Wrap-Up

Outside of class:
- Response to comments                - Blog commenting                           - Finish blog entries
                                                     - Blog discussions                           - Comment on 2 blogs
                                                                                                           - Take-home quiz

Finals grades for the course will be calculated by a point system consisting of 1000 points

- Quizzes (15 x 30 points)
- Blog reports (15 x 20 points)
- Blog discussions (Also required for each week)
- Final Project (150 points)
- Midterm Exams (2 x 50 points)
- Final Exam (150 points)


2. Electrical Circuit Lab Safety Rules:

1) Don't work alone on energized electrical equipment.
2) Power must be switched off when handling projects components, make sure high voltage points are grounded, also remember capacitors can store dangerous amounts of energy.
3) When measuring a live circuit, make measurements with well insulated probes while having one hand behind your back.
4) Never under any circumstances touch electrical equipment while standing on a damp or metal floor.
5) Never handle wet, damp or ungrounded electrical equipment.
6) Wearing any type of metal, such as a ring or watch can be hazardous in an electrical labratory since such items make good electrodes for the human body.
7) Never lunge for a falling part of a live circuit.
8) Never touch two pieces of equipment simultaneously
9) Never touch a wire of a circuit.
10) Avoid heat dissipating surfaces of high wattage resistors and loads (They can cause severe burns).
11) Some components have exposed metal that is "hot". Be careful when working with these.
12) Ask instructor to review your circuit before applying power to it.


3. As you know current is what actually kills, and a very small amount of current can be lethal (unlike voltage). A small current of 0.01 Amps can cause a person to feel a painful shock, muscle paralysis, and labored breathing. A current between the range of 0.1 - 0.2 Amps can cause the heart to stop. Currents 1 Amp or above are considered violent, as they can cause severe burns, as well as death by asphyxiation due to muscular paralysis of the lungs and diaphragm.


4.

5. The tolerance of a resistor depends on the last band. A gold band means the resistance is (±5%) and a silver band means the tolerance is (±10%). Tolerance tells us how far off the resistance value can be from its expected value. As for our data below, they all fall into our gold's tolerance range, which would account for the slight measurement difference of the DMM from it's value.


6.

Since the tolerance bands were gold on all of the resistors, the tolerance is supposed to be within 5%. The values in this table show very clearly that the actual values are all within 5% of the predicted value.


7. For current, the multimeter has to be in series so it can measure the flow. For voltage, the DMM has to be in parallel to measure the difference from both ends. Current has to measured in series because it flows thru the multimeter as a path. For voltage, the probes must be placed in parallel to the component that you are measuring the voltage across. This is because it's a measurement of difference between two points and the probes precisely give that value as if it were a distance.

8. The power supply allows you to change to any voltage value between the range of 0 - 24 volts, the values are considered continuous, basically infinite possible values. However, some circuits cannot handle voltage loads above a certain amount.

9.

10. To experimentally prove Ohm's law, we can put a resistor with a known value into a circuit, while also controlling it's power supply voltage. There is a visible correlation between voltage, and the amperage in the table pictured below. Since Ohm's law states I = V/R, calculations using the resistors provided value prove the relationship between the three types of measurements to be true.

11. The following video and picture is of our 1st Rube Goldberg circuit in action:

12. Here is a circuit diagram drawing of the 1st Rube Goldberg circuit:

13. Say The room is dark for the beginning of our Rube Goldberg circuit's scenario, by hitting a switch for another circuit, it lights an LED which triggers the photo-sensor to send power to the motor in our circuit, thus the motor begins to spin, pulling a stopping block which releases a marble in the direction of a pressure sensor (another portion of the Rube Goldberg circuit).

Picture of Scenario: