Lets put some Circuit analysis/theory, to practice...Newbies/Pros Plz read!! :)

[ENS Audio]

Hello there, I am trying to learn some bit of circuit analysis/theory from the ground up and so here I have this
Green Pre PSU schematic

I want to basically start with asking "What formulae(s) would I use to find common values such as Volts, Current and Resistance for starting with D1 (then adding C5 and C6 into the formulae)  (listed here) >>>

Bridge rectifier used which is the Bridge Rectifier 3A BR31 datasheet

http://www.rectron.com/data_sheets/br305-br310.pdf 

I dont need an "into" to how rectifiers/diodes work..I was just wondering how in the practical sense would I go about measuring correct values.


My goal behind this thread is to clear up any misunderstanding/confusion that I may have and to also prevent any additional "newbie" questions/threads from being asked in the near future for I have noticed that there are way too many redundant questions (which Im guilty of contributing to) that should be summed up in one "generalized" basic thread like this one for example ;D ...it will make "searching" less tedious..



Now I'll post the second part after I can get the first question summed up...


I'd like to go through  "component" by "component" or at least the first several/few that are in the schematic listed above.


Possibly if no "fiscal" surprises occur I can donate some money to this forum for it really does have real value to it when everyone participates in the Q n' A of these kind of threads


Thanks,

ENS Audio

 

[Ptownkid]

Also how would I decide which probe to connect???  (+) to? (-) to?

I'm totally confused by this question...I think you are asking how to read certain values using a meter, and if so (-) goes to ground and (+) goes wherever you want to get a reading from.

or i could be completely wrong with what it is that you are asking.

 

[gemini86]

http://www.allaboutcircuits.com/

enjoy...

I learned all my basic DC theory from automotive tech school, and studying on my own (via google and forums like these). A little research goes a long way...(and can greatly reduce redundant newb question, HEY! Two birds with one stone!)

 

[ENS Audio]

Also how would I decide which probe to connect???  (+) to? (-) to?

I'm totally confused by this question...I think you are asking how to read certain values using a meter, and if so (-) goes to ground and (+) goes wherever you want to get a reading from.

or i could be completely wrong with what it is that you are asking.

In other words if I wanted to find DC Voltage, Current or Resistance through D1 (Bridge Rectifier)....

Would I use  Ohm's Law??  Or something else? BTW didnt mean to jargon up what I typed up ealier

Hope I make sense :-[

 

[skipwave]

Boo....

 

[Gus]

http://www.groupdiy.com/index.php?topic=6887

 

[PRR]

> "What formulae(s) would I use to find common values such as Volts, Current and Resistance for starting with D1 (then adding C5 and C6 into the formulae)

This is not a calculation. You don't get a choice like in steel I-beams, 14" 30lb, 14" 37lb, 15" 43lb... you get 1A 2A 4A 8A, and at DIY pricing it is cheaper to over-buy than to think.

Transformer AC current rating twice DC load current.

Rectifier current rating greater than -transformer- current rating.

Rectifier voltage rating twice AC RMS voltage (and in low-volt work in DIY economics, use 400V everywhere because it is same-price as 50V).

C5 C6 are bull-pucks. They do NOT affect basic power delivery. They may sometimes be needed to suck-up MHz wobbles from the chips.

Your basic Power is stored on C1 C2 (omitted in your snippet). Use 1,000uFd per Ampere load current. Use more below 10V-20V, use less over 200V.

Do you have a half-clue what your Load Current is?

If you do, you'll note that C1 C2 are about 50 times bigger than "necessary". This is partly because the preamp is a very small-signal thing and we like clean power (even if we will be regulating). It is mostly because electrolytic caps are SO cheap that it is hardly worth fooling with anything less.

> to also prevent any additional "newbie" questions/threads from being asked

Not only is the question so far very BASIC and can be answered (though not clearly) with a bit of Googling, it has been touched MANY times here, and I know I've written the words above at least a dozen times.

You could also breadboard a 10-Amp transformer, a bridge of 1N914 diodes, 5uFd and 5,000uFd caps, and 10K and 10 ohm dummy loads. The '914s may even survive the 10A into 5uFd un-loaded, but fry with any load or large cap. Put in 1N4001 or 1N4007 diodes, they may survive but 5uFd filter with 10R load will have HUGE ripple. '01 and '07 diodes give the same result, can be found (DIY quantity) at same price, are cheaper by the 10-pack, use '07 for everything. 5,000uFd will clean the ripple, but a 10A winding into 1A diodes -will- eventually fail at turn-on.

You rarely measure current, especially around a rect-cap loop like this.

Back in the 1970s, Texas Instruments published a book of power supply design. Of course half of it was selling their then-new regulators, but the other half is a great reference. Is that re-posted on-line somewhere? (Rochey?)

 

[sahib]

Back in the 1970s, Texas Instruments published a book of power supply design. Of course half of it was selling their then-new regulators, but the other half is a great reference. Is that re-posted on-line somewhere? (Rochey?)

It is a fixed asset in my library. Motorola and GE also issued one around the same time and I got them too. Excellent engineering references. At a suitable time I would happily scan the reference half and post it on the forum.

Being on this forum with you is like being on the stage with a cracking guitar player. When you launch into a solo there is only one thing is left for one to do, stand back and watch. Although this occassion is no exception I would like to throw in this very basic, consolidated formula that will help the guys understand the relevance of the ripple between the capacitor and the load resistance.

C = 2405/T RL

or

T= 2405/C RL


T : Ripple factor
RL: Load resistance
C : Filter capacitor in microfarad
2405 : Constant for full wave rectifications.

 

[moamps]

http://sound.westhost.com/power-supplies.htm

on-line ripple calculator :

http://hyperphysics.phy-astr.gsu.edu/Hbase/Electronic/rectct.html#c3

 

[PRR]

The Voltage Regulator Handbook, Staff of Texas Instruments, Spencer and Pippenger, 1977
ISBN 0895121018, 9780895121011

It was clearly written because TI's staff had to sell the new Regulator Chips, but got tired of hearing the same-old "how big cap?" questions over and over.

And Google Books has a copy, but it is under copyright so they won't let you read more than snippets.

Where is 'Rochey' who seems to work for TI's support staff? He should tell his boss "Release copyright on TVRHB; we never got rich selling it, but it IS very useful to many people. And the TI name on the cover can't hurt. Tell Google to un-snippet their copy."

But it is worth paying for, if that's the way it must be.

Original review: "The Voltage Regulator Handbook is yours for four dollars; at three cents a page, it's a bargain." The price of everything has gone up, but a few of you can score for $10.

http://www.alibris.com/search/books/qwork/7080516/used/The%20voltage%20regulator%20handbook
http://www.amazon.com/voltage-regulator-handbook-Dennis-Spencer/dp/0895121018

 

[sahib]

Motorola book also carries the same title but it does not have ISBN;

Voltage Regulator Handbook
Author; Henry Wurzburg
Principal Contributors; Bernie Montoya, Cal Lidback, Nick Lycoudes

Part of the text is identical of the TI Book as it is based on the graphical data by Schade, 1943.

I recommend another book called Motorola Silicon Rectifier Manual. Although I have the 1980 print, it goes back to mid 70s. There was one on UK e-bay for 99p and it did not sell. What a shame. People are (mostly the younger generation) put off by the printing date of these books but they never realise that all the newer books are the repeat of old. In my view the great majority of new publication text books actually suck, because they assume a certain amount of knowledge hence edited badly.  A very good example is about transistor circuits. Overwhelming majority of books give an example of bootstrapped input to raise the impedance but fail to give the formula to calculate it.

 

[Gus]

Is the Motorola the white and baby blue covered one?  IIRC Radio Shack carried a NS regulator book IIRC I think it was a green cover.

1964 general electric transistor manual has good stuff in it.

Now I will need to look for my copies I have them stored someplace in the house.

 

[sahib]

My 1980 edition of Motorola book is Green cover. Previous edition was I think orange colour.

I have GE 1964 Transistor Manual. It covers transistor fundamentals and loads of application examples too. Great read.