Power Supply Question

[kbyrne]

I down loaded interesting new power supply for pre amps, tone control purposes. Upon examining
the schematic and board there is a difference in diode numbers. Could some one take a look at it
and advise me if this power supply is a working design or not as I am new but know how to set up the diodes and capacitors but lack in design experience?

Precision_15V_regulator_for_pre-amp_or_headphone_amplifier.pdf

sch.pdf

pcb_board.pdf

 

[liquibyte]

Which diodes are you referring to?  I took a look at both the schematic and the board and I noticed no discrepancies at all.  I've actually seen this design before on LT's pages and had considered building a version of it myself.  I'd say this is a working design but I've tended to notice that the only real way to determine if it does what it claims is to build it and try it out.

 

[kbyrne]

On the schematic D1 & D2 are at the 15v top together but on my PCB board pdf D1 & D3 are together
or am I wrong. On the schematic D3 & D4 are at the opposite 15v side of transformer but on my PDF
D2 & D4 are together. What I assumed was the text of the PCB was done wrong. On PCB PDF it goes from top to bottom D1, D2, D3 & D4. Am I right so far? ??? It should go D1, D3, D2, & D4.

 

[liquibyte]

Yep, you're right, the board and schematic are inconsistent.  How's this?

 

[Hero999]

Rather than messing around with PDFs, the address to the original image is at the top of each page.

It doesn't look like it'll work very well. The peak value of VCC will be around 15*sqrt(2) - 0.7 = 20.5V.  Q1 and Q2 are source followers with a voltage drop of over 5V for even a small current drain and 0.5V of headroom doesn't allow for much ripple.

If it's just a headphone amplifier, this could be fine but it's much easier to replace that op-amp and MOSFETs with an LM7815 and LM7915 which should give you superior regulation and current limiting too.

A properly designed audio amplifier doesn't need a well regulated amplifier. You could probably use a 12V-0-12V transformer, with an appropriate rectifier and filter capacitor.

 

[kbyrne]

Actually the address at the top of the page leads to a page that directs you to this project. Is this power supply workable with the change made to diodes Text of PCB board no matter what I use it for?
A larger amount other than 15v O 15v. What is the reason behind inductors L1 and L2 and where can I go to learn that fact?

 

[liquibyte]

I'd say it will work but listen to Hero999, he's got orders of magnitude more experience than I do.  I'd agree that if all you want is a + & - 15V supply, the 7815/7915 combo would be much simpler to work with.  Why reinvent the wheel if you don't have to, unless you want to experiment and learn that is.  Page two of http://electronics.howstuffworks.com/inductor.htm should give you an idea of what the designer intended with L1 & L2.  Now that I see this circuit again, I might just build it myself to see how it does.

 

[kbyrne]

Thank you I have the inductor info in my files. I like to try to build this type of project so I will give it a go and use my +15 gnd. -15 I already know all about for tone control circuits. Thank you for all responses. Best Kevin

 

[liquibyte]

Let us know how it works out.  I'd like to see the results after you get done and what, if any, issues you run into building it.

 

[kbyrne]

Will do. I have the SCH done in Express SCH and am working on PCB now in Express PCB. I also use
Xcheck, too check DRC, & Netlists & BOM. In the future I will post results as parts are easy to find. One more problem I saw under closer examination of inconsistent SCH and PCB. Below
IC1, and above IC2 there are two 1K resistors I fail to see on the schematic. I just missed these two
facts before I posted. How all of this got buy their proof reading of that web site I do not know. Does
any one know what is the purpose of those two resistors and if they are necessary as I am new and not good at design, nodal analysis ect?