Week 2, 18 - 23 January, 2016

  Due to the Holiday Monday we will only have one blog entry this week.
 
  Below are the questions posed to us by Dr. Kaya this week followed by our answers as well as pictures and videos for clarification purposes.

  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 is used to determine which potion of the power supply will be monitored by the built in Amp and Volt meters.  When” A” is selected the meters display the output amperage/voltage of power Supply A, and similarly if “B” is selected Supply B’s output will be displayed.   This switch only controls the integrated meters, and has no direct control over either supply, therefore it is possible for Supply B to be providing power while the A/B switch is in position A.

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

The 5v fixed channel has a 4 Amp current capacity meaning it can supply a constant 5v at 0-4 Amperes of current.  The Variable Power Supplies on Channels AB can supply a greater range voltage (0-24v) but can only sustain a maximum current of 0.5 Amperes 

  

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

A Brief video with audio explaining the operation of our power supply's main operating modes.

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

   Yes by putting the Power Supply in Series Tracking Mode and connecting the leads to Channel A's
         Positive output and Channel B's negative output the voltage can be increased to up to 48 volts.

Power supply configuration we used to achieve +30 V

  5.)     Can you generate -30 V using a combination of the power supply outputs? How? (Photo)
 
         Yes, -30 Volts can be achieved in the same manner as +30 Volts (See Question 4) with the only
         variation being reversing your connections so that the positive lead is plugged into the Negative
         output of Channel B, and the Negative lead in to the positive output of channel A.

Power supply configuration
we used to achieve + 30 V
(Also a pretty good photo bomb from Group 1)

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

         To achieve +/- 10V simultaneously we used the Series Tracking Mode with both outputs using the
         Negative Channel A terminal for their grounds.  The +10V output was connected to the positive
         Channel A terminal, while the -10V output was connected to the Negative Channel B Terminal

Photo showing the power supply configuration
we used to achieve +/- 10V simultaneously

  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 LED Light illuminated at approximately 20mA according to the integrated amp-meter. 
         The Current Knob was less than an eight of a turn above minimum at the time it illuminated.
         Both current and voltage decrease as the current limit is reduced.

Video showing the power supply connected to a 100 Ohm resistor as the current limit is decreased

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

        The Power Supply Fuse is located on the back side of the unit just below the power  cord.

        The Fuse protects the power supply's circuitry from over-current conditions

Power Supply Fuse

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

     

         The fuse for the DMM is located in the lower left corner of the front panel.  It protects the DMM  
         circuitry from an over current condition caused by connecting the meter to a circuit with an       
         amperage that exceeds the DMM's operating range.  A second fuse (not pictured) is located on the
         back of the unit this fuse protects the DMM from excess current coming from the wall outlet it is
         plugged in to. 

Front Panel of DMM.  Note the fuse holder in the lower left corner

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

   

           The two wire method of taking resistance is simpler but less accurate than the four wire method
          because it does not account for current loss due to resistance in the leads which can lead to
          inaccurate readings in circuits with small amounts of resistance.  The four wire method is a bit
          more complicated to set up but increases accuracy by using four leads (2 to measure amps two to
          measure volts) then calculating resistance based on measured current and voltage

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

          To measure a current of approximately 10 Amps you would plug your positive lead into the Red
          15A max Fused port on the DMM and the Negative lead into the Black port.  You then need to turn
          the range selection to manual using the "Auto <" button and manually select the appropriate range
          using the up and down arrow buttons.