week 2

Blog sheet week 2

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

The role of A/B switch is Selects Simultaneous Voltage & Current metering for the “A” or “B” supplies. For example, when in the A position, the V and mA meters are connected to the “A” supply. When in the B position, the V and mA meters are connected to the “B” supply. So if I am on A, B would still give me a voltage.

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

0.5A or 4A means current capacity: the 0-24V supplies are adjustable and are capable of current output of 0-0.5 amp. The fixed 5V supply has a current output of 0-4 amps.

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 and the “A” and “B” power supplies are completely independent from one another: when used in the independent operating mode, the operating controls of the two power supplies are completely independent and either supply can be used individually or both can be used simultaneously.

There are two tracking mode: serious tracking and parallel tracking. In the series tracking mode, the “B” supply tracks the voltage of the “A” supply. In the series tracking mode the “A” and “B” supplies are connected in series, allowing a single output of 0-48V at up to 0.5 amps. In the parallel tracking mode, the two supplies are connected in parallel, allowing a single 0-24V output at up to 1 amp.

4.     Can you generate +30 V using a combination of the power supply outputs? How? (Photo)
      In order to generate 30 volts we put channel A and B in series tracking mode. We then adjusted to voltage of each channel to 15 volts. Then added together we get 30 volts.

5.     Can you generate -30 V using a combination of the power supply outputs? How? (Photo)
     To generate -30 volts we did the same thing we did to generate 30 volts, but we switched the polarity.

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

      In order to get 10 V and -10 V at the same time we grounded the positive terminal for channel B, and then measured the voltage of channel B at the negative terminal. This gave us our -10 volts. When we measured the voltage at the positive terminal of channel A we got 10 volts. 

7.     Apply 5V to a 100 Ω resistor and measure the current by using the DMM (remember the setup in DC 3). 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)

      The angle of the current knob makes the LED light on is about 30 degree as the figure shows.

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

Fuse is a device used in electrical systems to protect against excessive current (From https://en.wikipedia.org/wiki/Fuse). The receptacle of fuse shows in the figure below.

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

Fuse is a device used in electrical systems to protect against excessive current (From https://en.wikipedia.org/wiki/Fuse). The receptacle of fuse shows in the figure below.

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

They are different in input protection limits. The maximum allowable input of 2W resistor is 500V dc or ac rms; the maximum allowable input of 4W resistor is 250V dc or ac rms;

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

In this picture you can see the normal set up to measure low current.

(picture of normal set up)

In this picture you can see we moved the positive lead to the 12A port. This would allow us to measure current close to 10A.

(picture of the 12A set up)

week 1

Monday:

1.     What is the class format?

Monday: Quiz, Lab intro, Lab, and Wrap-up.

Wednesday: Lab and Wrap-up.

Friday: Blog discussions and Post-quiz.

2.     What are the important safety rules?

•Remember where the fire extinguisher and first aid kits, and remember telephone and emergency numbers.

•Don’t work with the defective equipment.

•Clean/tidy up!

•Power off while not working.

•Grounding.

•No wet hands.

3.     Does current kill?

Yes!

4.     How do you read color codes? (Video)

5.     What is the tolerance? Give an example from your experiment

Tolerance is the amount error that there can be from the designed resistance. The tolerance on our resistors was five percent, so this means the resistance in them could be five percent higher or lower of the intended amount. For example our 1500 ohm has a tolerance of five percent, and our measured amount was 1490 ohm. So this is within .67 percent which is within the allowed five percent tolerance.

6.     Prove all your resistors are within the tolerance range

Resistor value (Ohm)	Actual value (Ohm)	Error percentage (%)
1.5k	1.49k	0.67
120	119	0.83
360	355.8	1.167
150k	147.7	1.53
15k	14.75	1.67
1.5k	1.48k	1.3
2.2M	2.2M	0
47	46	2.1
2700	2708	0.3
820	816	0.49

The error percentages of all resistors are smaller than 5%, so all the resistors are within the tolerance range.

Wednesday:

1    1.  What is the difference between measuring the voltage and current using a DMM? Why?
      
     When you measure voltage with the DMM you measure it in parallel. When you measure the current you need to break the loop and take the measurement with the DMM in series with the circuit. You measure the voltage in parallel because you are measuring the difference across two points. In order to measure the current, the DMM must be in series with circuit so the current will flow trough the DMM.

2    2.     How many different voltage values can you get from the power supply? Can each one of them be changed to any value?
         
      For first channel the voltage is fixed at 5 volts, the other two can be adjusted anywhere between 0 and 25 volts.

3    3.     Practice circuit results (video) & (photo)

      

       Measure voltage:

    

Measure current:

                                                   

                                         

4    4.     How do you experimentally prove Ohm’s Law? Provide measurement results. Compare calculated and measured voltage, current, and resistance values. (Experimental setup photo)

      

      Ohm's Law: voltage/current = resistor.
    

For the 147.7kΩ (measured value):

Voltage (V)	Current (A)	Resistor (Ω)
5.02	0.0337	148.96
7.57	0.0511	148.14
10.09	0.0682	147.95
12.68	0.0857	147.96
15.01	0.1016	147.77
17.43	0.1180	147.73

For the 14.75kΩ (measured value):

Voltage (V)	Current (A)	Resistor (Ω)
5.01	0.3395	14.75
7.57	0.5134	14.74
10.1	0.6842	14.75
12.7	0.8600	14.74
15.0	1.0190	14.73
17.4	1.1835	14.73

The experimental set up will be the same us measuring voltage and current.

      Measuring current:

Measuring voltage:

5    5.     Rube Goldberg circuit (video).

Friday:

1.  Draw the circuit diagram for the Rube Goldberg set-up.

2.  How can you implement this setup into a Rube Goldberg machine? Drawing required.

After getting the power from the Rube Goldberg set-up, we can use it to power the dryer, and then use the wind from the dryer to blow the ball to the pinball track and use the basket to catch the ball finally.