# Switching Mode Power Supply Explanation Help

Discussion in 'Homework Help' started by mjcole82, Nov 27, 2012.

1. ### mjcole82 Thread Starter New Member

Nov 3, 2011
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I have a lab to do on analog circuits. This is the circuit I was assigned. I know it is a switching mode power supply, but the teacher has told us nothing about it. Only gave us a link to some indecipherable indian guy on youtube.
Essentially, I just need to know the process of how to set the values of the components. I know how to do all the relevant formulas, just can't figure out where to start. Seems like everytime I try to figure out one value of a component, I need the value of another I don't know and so on in a vicious circle.

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2. ### crutschow Expert

Mar 14, 2008
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Look up hysteretic switching regulator.

The relative value of R1 and R2 determine the output voltage as compared to the reference voltage V2.

The relative value of R3 and R4 determine the value of the hysteresis voltage for the U2 switch around the reference switching point.

3. ### bountyhunter Well-Known Member

Sep 7, 2009
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more evidence to support my claim that computers are making the world lazier and stupider than it already was......

justtrying likes this.
4. ### mjcole82 Thread Starter New Member

Nov 3, 2011
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Thank you for taking the time to reply in a completely useless way. Computers, and the internet, give people access to information that was previously nearly impossible to obtain at such speed. A person would be a fool if they did not see it wise to take advantage of this resource. You, obviously, perceive this as laziness. I see it as using the tools I have at my disposal.
Finally, just because I made this post does not mean I didn't spend hours doing other research in other places. Once again, thank you for being one of those people that clutter forums with completely useless drivel.

5. ### bountyhunter Well-Known Member

Sep 7, 2009
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Listen, dude: I perceive LAZINESS as laziness and here is exactly what you said:

That's the problem. I have a total of three engineering degrees and I am constantly stunned by what passes for "teaching" these days. If any instructor had dumped an assignment on me with no collateral information (and a few did) I would simply camp at his office until he told me what he should have told the class in the first place.... which was a learning experience for him since he learned it's better to actually teach the CLASS in unison than have them come to his office in single file to get the information he was too lazy to prepare for the class as he should have.

I know exactly what computers are good for, I use one every day. I also know that many teachers are using them to be lazy and this is a good example of it.

And BTW, I spent about 20 years teaching which is to say I prepered volumes of technical material for training classes so I know what I'm talking about. Doing it right is a lot of work, doing it wrong is a lot less work and you get what you put in... of course, I would have been fired for doing what your instructor did but in private industry you actually have to do the job you are paid for, we didn't have the protection of "tenure" and a powerful teacher's union who defend the jobs of incompetent teachers.

As for:

Why is it useless to point out that when a student has received no information from a teacher..... never mind, I give up.

Last edited: Nov 29, 2012
6. ### Audioguru Expert

Dec 20, 2007
10,397
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Does the teacher's union say that a teacher who does not do their job still gets paid?
I am not talking about their enormous pension when they retire.

A teacher on my street retired while still fairly young. The pension pays full salary (from my taxes!). This teacher has a new job with the school board for even more income.

7. ### bountyhunter Well-Known Member

Sep 7, 2009
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It certainly does, The worst teachers (who have tenure) are fully protected by the unions to the point of insanity. I could tell you tales you might not believe but are true none the less. Unions spend 99% of their resources (including their legal counsel) defending the worthless scum who should be fired. If you have ever wondered why public education is what it is, that reason tops the list (see references at the bottom of this post).

Yep, another problem.

The classic double dipper.....

Last edited: Nov 29, 2012
8. ### JoeJester AAC Fanatic!

Apr 26, 2005
3,898
1,731
mjcole82,

Are you paying the institution for the class your taking?

Dec 4, 2009
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That is too much of very strong words for a casual remark or personal opinion, and that too to someone who is very highly experienced and has been actively offering valuable help here.

10. ### crutschow Expert

Mar 14, 2008
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I'm not sure I understand the relevance of that question.

11. ### bountyhunter Well-Known Member

Sep 7, 2009
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Yeah, it's inexcusably terrible teaching either way but I would be a lot madder if somebody I was paying directly had shined me off that badly....

12. ### Audioguru Expert

Dec 20, 2007
10,397
1,140
The lazy teacher tells the students to look online then he goes to play golf.
A teacher should TEACH things and is paid to TEACH things.

Maybe the lazy teacher had a teacher who never taught how to teach.

13. ### Audioguru Expert

Dec 20, 2007
10,397
1,140
Deleted a double-post.

Last edited: Nov 30, 2012
14. ### mjcole82 Thread Starter New Member

Nov 3, 2011
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Yes, I pay nearly \$2000 per class. Which does not include books or my parts kits.

15. ### mjcole82 Thread Starter New Member

Nov 3, 2011
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My apology, I thought you were calling me lazy for asking for help on this forum. I now see that you were referring to the teacher.

16. ### JoeJester AAC Fanatic!

Apr 26, 2005
3,898
1,731
You are not getting any value for that 2000 your spending. If the teacher isn't teaching, they report to someone, like the Chair of the department, and the Chair reports to someone.

It's a shame you are spending that much cash and not getting anything in return.

My wife complained to the Chair about a course's false advertisement ... Statistics using Excel, and the teacher stated on the first day that he didn't know anything about excel. She got her money back.

So you are paying for the privledge of sitting in a class for a semister. I haven't read where learning by osmosis has been perfected.

17. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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Do you have ANY of the design parameters, such as input voltage, output voltage, allowable output voltage ripple, output current ability, etc? It's a little on the impossible side to design without that information.

There have actually been two large studies done and a few smaller ones, showing no correlation between higher teacher wages and better student performance. In fact, they tend to prove the inverse up to high school level, and then no change through college education.

18. ### bountyhunter Well-Known Member

Sep 7, 2009
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Have there been any studies about the correlation between unions protecting incompetent teachers and poor quality public education?

The study I did.... during about 12 years of schooling I attended in california certainly supported it.

Last edited: Dec 2, 2012
19. ### bountyhunter Well-Known Member

Sep 7, 2009
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apparrently, you do get what you pay for:

http://www.rand.org/pubs/working_papers/2006/RAND_WR378.pdf