Wednesday, January 18, 2017

Blog 2 Group 1

Scout Case and Austin Kane

1.  What is the role of A/B switch?  If you are on A, would B still give you a Voltage?
The role of the A/B switch is it allows you to switch between two different adjustable voltages between 0-24 Volts.  If A is on, B will still be giving a voltage however the reading on the power supply will only read the voltage supplied to A.  If it is in Tracking mode it it can be linked in parallel or series with A which essentially means A and B are connected.

2. In each channel, there is a current specification (either 0.5 A or 4 A). What does that mean?
For each channel that is the max current allowed before it overloads the circuit.  .5 A is with the A and B switch because it can go up to 24 V.  The 4 A is for the fixed 5 V channel.

3. Your power supply has two main operation modes for A and B channels; independent and tracking. How do those operation work? (Video) 
Video 1: Shows the difference between tracking and independent mode.

The operations work like this.  In independent mode the voltages are free of each other. In tracking mode the voltages are linked together, allowing to get higher voltages we normally wouldn't be able to obtain.  In series tracking mode you can achieve up to 48 V and a current of .5 A.  In parallel you can achieve up to 24 V but a current of 1 A.

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

Fig 1: Shows a reading of +30 volts on the DMM
Fig 2: Shows the setup for the +30 volts reading.

Yes, you can achieve this by putting the power supply on series mode allowing the two voltages to link together.

5. Can you generate -30 V using a combination of the power supply outputs? How? (Photo)
Fig 3: Shows a reading of -30 Volts.
Fig 4: Shows the setup for the -30 Volts.

Yes, you can achieve this by just switching the ground and positive terminals which would make it read from the negative side.

6. Can you generate +10 V and -10 V at the same time using a combination of the power supply outputs? How? (Photo)
Fig 5: Shows a reading of -10 Volts.
Fig 6: Shows the reading of +10 Volts.

Yes, you put them in series mode.  You change the positive lead of the multi-meter to read from the negative terminal and then to the positive terminal.

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)
Video 2: Shows a video of how the current controls the circuit.

The light will come on if the angle of the knob gets below what is required to run the circuit. The video will show the angle.  If you keep decreasing the knob below the required current limit, both the voltage and the current will begin to drop until there is no voltage and current left. In addition, the LED will come on indicating that the current is being fixed as opposed to the voltage.

8. Where is the fuse for the power supply? What is it for?
The fuses are located in the front by the fixed and A channel.  There is also a fuse located in the back underneath the cord, which is the fuse for the power coming in.  The fuse is used to limit the current coming through the power supply.  If the current gets to high then the fuse will blow to cause a break in the circuit so that there is no current running through it. This safety feature helps protect the more expensive components of the power supply.

9. Where is the fuse for the DMM? What is it for?
The fuse for the DMM is located in the bottom right corner of the front panel.  There is also a fuse located in the back of the DMM by the plug.  Once again, in order to protect the more expensive components of the equipment if to much current goes in (2 amps is the max) it will trip the fuse not allowing current to flow.  There is also another location on the DMM that you can use up to 15A max, which doesnt use the same fuse as the 2A max fuse.

10. What is the difference between 2W and 4W resistor measurements?
The difference between a 2 wire and 4 wire resistor is that the 4 wire is for lower resistances because it reduces the effect of test lead resistance.  2 wire can handle up to 100 ohms of resistance.  For the 4 wire resistance, it can handle up to 1000 ohms.  So the difference between the two would be how much resistance each can handle.

11. How would you measure current that is around 10 A using DMM?
Instead of using the normal setup for current, which uses the 2 A fuse, you would use the 12 A setup which has a max of 15 A. The ground would stay the same, just the positive lead location changes.


  1. There appears to be a typo in your work. In question 9 you claim that the DMM can only take 2A. However, later on you go on to explain how it can measure 10A. You are indeed correct, if you look at the front of the DMM you can see that it has a rating for up to 12A max, then of course the fuse will blow.

    Other than that particular issue, I like the overall layout of your blog, the questions being bold helps them stand out.

    1. Thanks Alec for pointing that out! Should be all fixed now. Thanks for reading it and helping us out.

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  3. I believe that you have the 2-wire and 4-wire resistance values reversed. As far as I can tell, it is more beneficial to use a 4-wire for lower resistances. This is because the greater amount of wires allows for more accuracy because it reduces the effect of test lead resistance. Here is a link I found that may explain it better.

    1. Thank you for pointing that out. That article made it very helpful to understand the actual answer. Thanks Nick!

    2. I didn't know until this lab that you could reverse the polarity of the 30 V and add the voltages together! That is so cool. Also remember that the 2W and 4W are all about accuracy! The 4W is not going to add a +- ohms to your value. Good job on the videos though they were put together nicely!