Lab 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 A/B switch tells the V meter and mA meter of the power supply to either show the current and voltage of the A or B channel. Regardless of the position of the switch there is voltage being applied to both channels.

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

     

      The fixed 5V supply can provide a 0-4 amp current depending how much the circuit requires. The two supplies labeled “A” and “B” are the 0-24 Volt supplies. They continuously supply voltage within that range and each has a 0.5 amp current capacity. 

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

      When the power supply is on independent operation mode, which is when the button is all the way to the right, the “A” and “B” power supplies are completely independent from one another. Tracking mode can be in positions Parallel or Series. When the switch is in the middle position it is in Parallel tracking and the “A” and “B” supplies are wired together. The current and voltage can be adjusted using the “A” controls. The two controls can also be used independently, but somewhat follow one another, also known as tracking. The output can be used as a 0-24 volt supply with a 1 amp capability. When the switch is the left position the power supply is in Series tracking mode. In this setting the “A” controls are used for the maximum voltage of both supplies. In this mode the voltage terminals at “B” supply tracks the voltage on the “A” supply. The positive terminal of “B” is also internally connected to the negative terminal of “A” supply which allows the two supplies to be used as one 0-48 volt supply. 

            Here are two videos explaining the differences between the switch positions.

Video 1:

A video containing the first half of a 51 second clip showing the differences between switch positions.

Video 2:

A video showing the second half of a 51 second clip showing the differences between switch positions.

     

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

   

        Yes, the power supply must be in series mode and your ground probe should be in negative slot on the B supply and the positive probe should be in the positive slot on the A supply.

A picture of +30V output and the connections used to obtain it.

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

       Yes, the power supply should be in series mode and your ground probe should be in the positive slot on the A supply and the positive probe should be in the negative slot on the B supply.

A picture of -30V output and the connections used to obtain it.

                         

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

       Yes, you can get +10v and -10v at the same time.  What you need to do is connect two power supplies in series at 10V each so you have a total of 20V.  When you measure you ground the DMM in between the two power supplies, at the positive terminal of the first power supply.  To measure the to get +10V you connect the red wire to the positive terminal of the second power supply and to get -10V you connect the red wire to the negative terminal of the second power supply.

A picture of +10.29V output and the connections used to obtain it.

A picture of -10.29V output and the connections used to obtain it.

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)

       On the DMM we have a reading of 2.5 micro amps and on the power supply we have a reading of 30 mA.  When the current knob indicator is approximately 45 degrees from 0 setting the LED indicator light turns on.  When you hit 45 degrees from the minimum the voltage and current decrease with each additional degree you move the knob. 

A video showing the angle at which the LED light comes on.

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

       

       The fuse for the power supply is located on the back below the power cord connections.  The fuse is there to ensure the equipment is not damaged in case of an overload in current.

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

       The fuse for the DMM used in class is located on the back below the power cord connector. The purpose of the fuse is to protect the equipment in case of an overload in current.

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

       98.058 4W measurement

       97.843 2W measurement

      

       2W stands for 2-wire resistance measurements and can get good measurements at higher resistances. 4W stands for 4-wire resistance measurements and is often used to measure lower resistance values. 

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

        You would plug the positive terminal into the bottom right connection on the front of the DMM and the negative terminal into the original slot.  You then use the up arrow to select the amps measurement.