The simplistic Salas low voltage shunt regulator - Page 192 - diyAudio
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Old 2nd March 2010, 03:01 PM   #1911
klewis is offline klewis  United States
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Quote:
Originally Posted by HiFiNutNut View Post
The picture in post 1898 is only a wiring guide with perfboard. With standard ExpressBCP I can't find the symbols for the right sizes of the transistors. Note that the MOSFETs were drawn as TO-220 type but should be TO-247. I also soldered all gate stoppers directly at the MOSFET legs.
I made you a TO-247 for express pcb. see attached.

Ken
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File Type: zip TO-247.zip (523 Bytes, 190 views)
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Old 2nd March 2010, 03:14 PM   #1912
estman is offline estman  Estonia
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Default output capacitor

http://calex.com/pdf/3power_impedance.pdf
Is it useful to follow these instructions in choosing output caps?
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Old 2nd March 2010, 05:50 PM   #1913
Salas is online now Salas  Greece
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The proper RC Zobel is already there as you can see on the ccts. The paper you linked is correct in general. Because the termination is a sensitive matter, that is why a film cap is specified there, so the resistor should surely determine it without uncertainty due to widely variable electrolytic specs, also not stable with heat and aging. To guard off bad interaction like oscillations or performance degradation when applying these ''speedier'' ccts, its advised to check all is well with an oscope on the supply lines (see no wiggles). If there is some local decoupling on the audio circuits already fixed, there is chance for incompatibility, especially if there are very small value/low ESR capacitors across supply lines to ground. Its a total reg/audio client system with many factors and parasitics, oscope is your friend and decoupling can be deleted or altered locally on the client boards if problematic cooperation occurs. V1.0 is designed with less edge performance but has broader tolerance, it can always be employed with remote sensing to enhance it even, if the situation is decidedly reactive with no solution when with V1.2. Performance gains are seldom a plug n' play game in a total system, although V1.2 has shown good behavior in compatibility up to now. That was one of the main goals of the independent beta testing effort btw.
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Old 2nd March 2010, 07:44 PM   #1914
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Quote:
Originally Posted by klewis View Post
I made you a TO-247 for express pcb. see attached.

Ken
That is nice. Can I export the component and import it into the general component library so that all my new files can use it? If so, have you got a resistor with 2 x 2.54mm handy?

Regards,
Bill
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Old 2nd March 2010, 08:54 PM   #1915
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Quote:
Originally Posted by estman View Post
http://calex.com/pdf/3power_impedance.pdf
Is it useful to follow these instructions in choosing output caps?
It depends on the actually load. The output of the regulator not only sees the output capacitor, but also the load, including the local bypass capacitors. The whole should be treated as one unit.

We often hear comments that one regulator is good and another one is not so good, or for the same regulator, one says it is good and another one says it is bad. I think for a given well designed regulator, it is always good by itself, it is the interaction of the regulator with the load that determines if the regulator can perform well or badly.

From the output of the regulator to the circuit board, there are wire inductance and resistance. The circuit has parasitic capacitance. The LCR forms a resonant circuit.

I found with my opa627 buffer, there is input capacitance that causes resonance. I use a 2.2uF film capacitor in series to 1R resistor as local bypass / damping circuit and this completely kills the resonance.
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Old 2nd March 2010, 09:23 PM   #1916
DougL is offline DougL  United States
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Quote:
Originally Posted by Salas View Post
Its about the performance things discussed in this thread.

The cascode tail increases the psrr of the ccs. Vbe ref for no Rset hassle with LEDs. Cascoding brings it up to par.
The resistor comes handy for an adjustable output. Its low noise enough but leds are better, and stiffer for drift btw.
The RC feedback is a compensation to keep oscillations away.
The buffer helps open up Zo performance in frequency.
Rsensing is a good practise not to throw the better performance measures out of the window.

About subjective merits, I hand it over to the testers.
Thanks for the explanations.
Just what I was looking for.

The engineering of this is very high level.
Hats off to you.

Doug
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Old 2nd March 2010, 10:09 PM   #1917
Salas is online now Salas  Greece
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You are welcome. Credit must be given where credit is due and we shall not forget thanking Ikoflexer for keeping the topic alive seeking performance.
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Old 3rd March 2010, 01:22 AM   #1918
iko is offline iko  Canada
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Hey, thanks, but this is your baby, and it rocks! Looks good Salas, well done!
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Old 3rd March 2010, 01:33 PM   #1919
klewis is offline klewis  United States
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Quote:
Originally Posted by HiFiNutNut View Post
That is nice. Can I export the component and import it into the general component library so that all my new files can use it? If so, have you got a resistor with 2 x 2.54mm handy?

Regards,
Bill
Bill,

Open the file I sent, with the arrow pointer tool (top one lefthand side) select the symbol, from the list across the top of the screen (File, Edit, View, Component, etc.) select Component/Save custom component... Now it will be in your library. Then when you go to place a component and go to the pull down list, you'll see it in the first group - custom components.

So, you know, I made it in about half a minute, it took longer to zip and send than to make. I don't have a 2 x 2.54 resistor, but, you should try making one.

Start by placing a through hole pad of the desired size. Then under View/Set Origin with mouse, place the Origin at the center of the pad, (it helps if you zoom in). Now place a second pad at the appropriate distance from the first pad, because you moved the Origin and the first pad is at 0,0, the X, Y readout at the bottom lower left will show you where where the second pad is relative to the first without having to do any math. Now select the first pad with the arrow tool by double clicking on it. Make it pin no. 1, select the second pad, make it pin no.2. These pin numbers correspond to the numbers on the schematics, so, for more complex parts, you need to look at the data sheet and make sure your pin numbering is consistent. Then select the the line tool, pic the yellow line, and draw the outline of the resistor. After drawing, with the arrow tool select the whole thing. Then select Component/Group to make PCB component, then do the Component/Save custom component... give it a name and it's in your library.

Ken
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Old 3rd March 2010, 09:36 PM   #1920
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Ken,

Thanks. I have now made my resistor.

Regards,
Bill
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