Dual output dc power supply questions

[†D-fy†]

Hi, actually someone already posted the same questions but I thought it would be weird to continue from that post as I have a lot of questions of my own.

The assignment requires me to draw a schematic diagram of a dual output dc power supply, identify the sub sections that make up the power supply and lastly a report on how the power supply operates.

Ok, before I can NOT fully rely on the others' help to answer these questions I need to ask a few questions of my own because I absolutely know nothing about dual output dc power supply. Here goes...
1) What is a dual output dc power supply?
2) What does it do?
3) How does it do it?

Well, thanks for helping.

 

[Redbelly98]

Hi,

1) As the name suggests, it is a power supply with two separate outputs. They will be at different voltages: usually a positive and negative of the same value, but sometimes not. Examples: +15V and -15V, or +5V and +12V.
2) It outputs 2 voltages. For example, having both +/-15V is convenient for powering op-amps.
3) There are different ways to do this, I suppose. You might try a Google search on "dual output" "dc supply" and see what pops up. Adding the term "schematic" to that search might help too.

 

[†D-fy†]

I tried searching with google and other search engines but I can't seem to find any useful information. All I found was links to advertisement of products of the power supply by different companies.
I wish someone can help.

 

[†D-fy†]

Umm by the way, anyone can tell me if a dual polarity dc power supply and a dual output dc power supply are the same thing or are they different?

 

[†D-fy†]

Oh I forgot to mention that the assignment requires the dual output dc power supply to have the outputs of +15V and -15V and also it must have not more than 15 components. What does the "components" refer to anyway?

 

[Redbelly98]

Components are things like diodes, transformers, resistors, capacitors, and i.c.'s (integrated circuits). It would not include wires, connectors, or plugs.

I'm a little curious about this course and assignment. Does the professor assume you have been taught the necessary material in course lectures or textbook reading, or is it more of an independent study/research type of assignment?

Here is a schematic for a single-output dc supply:
http://home.maine.rr.com/randylinscott/nov98.htm
The circuit has 10 components. One could probably leave out the switch and fuse, for 8 components.

 

[Redbelly98]

Umm by the way, anyone can tell me if a dual polarity dc power supply and a dual output dc power supply are the same thing or are they different?

Not 100% sure, but I think "dual output" refers to any supply with 2 output voltages. It could be dual polarity (positive and negative), or not (2 different positive voltages, for example).

 

[CarlB]

A dual output power supply for +15V and -15V also requires a ground output.

Given only a dozen or so components, I'd be looking at center tap transformer, two rectifiers, about a half dozen capacitors, and a couple of voltage regulator chips. After getting something that regulates together, the most important thing is to verify that the components are specified so that they pass the smoke test. I.e. sufficient current and volage specifications.

You also need to have specified the incoming power. Maybe 120 VAC? Or perhaps DC which will require a switcher and may be problematic to keep under the parts list. Other things to think about: on/off switch. Power plug. Fuze. output jacks.

 

[†D-fy†]

I'm a little curious about this course and assignment. Does the professor assume you have been taught the necessary material in course lectures or textbook reading, or is it more of an independent study/research type of assignment?

I think the teacher wants us to research ourselves but he did not take into consideration that, not knowing anything, it would be very difficult for us to even understand our "research". What's worse is that almost none could find anything online.

Not 100% sure, but I think "dual output" refers to any supply with 2 output voltages. It could be dual polarity (positive and negative), or not (2 different positive voltages, for example).

So with output of +15V and -15V, the dual output dc power supply is also a dual polarity dc power supply?

Oh and thanks CarlB, if only the teacher had taught something about what you just said, I could have used what you said to draw the schematic...but I really don't understand what you said...I also saw a schematic somewhere but I don't understand it at all too...

 

[Redbelly98]

Sorry for being absent from this thread for the last 24+ hours. I am still unclear on just how thorough the teacher expects the assignment report to be, given that:
1) The students have little (or none?) exposure to electrical circuits, and
2) This seems to be a high school physics course (since you refer to your "teacher", not your "professor"), but I could be wrong about that. To my knowledge circuits like this normally appear in college-level electronics courses.

At this point, here is what advice I can offer:
1. Can you understand the schematic I linked to in Post #6, for a single-output power supply? A dual supply would be similar, but of course more complicated because there are 2 voltage sources instead of just one.
2. Can the teacher recommend a source or reference to look this up? A book in your library perhaps?

So with output of +15V and -15V, the dual output dc power supply is also a dual polarity dc power supply?

Yes. But I would go with whatever term or phrase is used by the teacher in the assignment write-up.

 

[Redbelly98]

Just found this Wikipedia article, which is a decent introduction to how many of these supplies work:
http://en.wikipedia.org/wiki/Diode_bridge