Week 2

Wednesday

1.) What is the role of A/B switch?

The role of the A/B switch is to specify which supply is being displayed on the meter. If the switch is on A, B still gives voltage.

2.)  What do the current specifications for each channel mean?

The current specified are the max current allowed per channel. Up to 4A for the fixed 5V channel, and up to .5A for the A and B channels.

3.) Power supply modes: independent and tracking.

Independent mode is when the A/B switch is used to control the voltage of the outputs independently. 

Tracking mode has two different categories:

Series Tracking mode is when the the negative B terminal is connected to the positive A terminal, functioning in series to each other. One dial (A) can be used to control the output and the actual metered output is double the displayed voltage.

Parallel Tracking mode: A and B outputs function in parallel to each other. The B controls do not work, only A output terminal controls should be used. Current is doubled.

Figure 1: Shows the different modes of the power supply.

4.) Can you generate +30V?

By putting the power supply in series tracking mode, it is possible to achieve up to 48V, so by setting the output to 15V, the supply is actually giving 30V.

Figure 2: the +30V output using series tracking mode.

5.) Can you generate -30V?

Yes, by using the same method as #4, set in series tracking mode but with the polarity reversed will give a -30V instead of +30V.

Figure 3: the -30V output using series tracking mode.

6.) Can you generate +10V and -10V at the same time?

Yes, by setting the power supply to independent mode, 2 different simultaneous outputs can be achieved. To get -10V, the positive and negative leads of the DMM have to be connected to the opposite outputs of the circuit. For +10V the leads are connected traditionally.

Figure 4: Is the +10V output using independent mode.

Figure 5: Is the -10V output using independent mode and reversing the leads of the DMM.

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)

Figure 6: shows the response of a 100ohm resistor to 5V

In the video, the current readings on the power supply and DMM are compared and are found to be very close. Then, the current dial is adjusted until the constant current light turned on which occured when the dial was between 8 and 9 o'clock. Lastly, it was shown that as the current dial is lowered, the voltage reading responds directly and decreases as well.

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

The fuse for the power supply is located on the rear panel. The purpose of the fuse is to prevent excessive current from damaging the device.

Figure 7: is the rear panel of a Triple Output DC Power Supply

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

The fuse for the power supply is located on the rear panel. The purpose of the fuse is to create an open circuit when the circuit is overloaded in order to prevent any damages to the DMM.

Figure 8: is the rear panel of the Digital MultiMeter

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

4W is more accurate for lower resistance testing because it cancels out wire resistance, 2W is less accurate for lower resistance because it doesn't cancel out wire resistance which in turn gives an improper reading.

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

To measure current that is around 10 A using the DMM plug positive lead into 12A max port. This should allow us to measure this current.