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Old 14th May 2012, 05:45 PM   #11
dtproff is offline dtproff  United States
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Guess I'll dig a little deeper here.

When you say "Noise" do you mean transient response or the 120Hz ripple and EMI coming in the AC Line cord.

Tony
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Old 14th May 2012, 08:17 PM   #12
agdr is offline agdr  United States
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Quote:
Originally Posted by andrea_mori View Post
I believe that a CLCRC filter is a good way to decoupling regulator from AC, either for analogue than for digital, so I think we can use it in both case.
^+1 (agreed). I've had good results with CRCRC filters before the regulator chip. I'm using several right now. Just be sure to solder small (0.1 - 0.01uF) XLR or COG MLCCs right across the electro leads in each section to also nuke the stuff above the audio band traveling in both directions (from the line and to the line in the case of digital).
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Old 14th May 2012, 09:08 PM   #13
PET-240 is offline PET-240  Australia
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Dumb Question Number 1:

What are these things?

Quote:
Originally Posted by agdr View Post
^+1 (agreed).small (0.1 - 0.01uF) XLR or COG MLCCs right across the electro leads in each section to also nuke the stuff above the audio band traveling in both directions
I am assuming caps of some sort but clarification would be nice....

Thanks,

Drew.
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Old 14th May 2012, 10:10 PM   #14
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Quote:
Originally Posted by dtproff View Post
Guess I'll dig a little deeper here.

When you say "Noise" do you mean transient response or the 120Hz ripple and EMI coming in the AC Line cord.

Tony
About shunt regulation, I mean all undesirable noise coming from previous stage, since it provides a path from the supply voltage to ground through a variable resistance.
Feed forward shunt provides a better supply noise rejection than feedback shunt, although it is more difficult to implement because you must predict the maximum noise to be canceled in the design.

Andrea
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Old 15th May 2012, 01:25 AM   #15
qusp is offline qusp  Australia
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Quote:
Originally Posted by PET-240 View Post
Dumb Question Number 1:

What are these things?



I am assuming caps of some sort but clarification would be nice....

Thanks,

Drew.
yes they are types of ceramic cap. MLCC is multilayer ceramic capacitor, Np0 or c0g are the same thing and are tempco ratings. NP0 stands for Negative Positive Zero, meaning that the capacitance does not change over temperature. for c0g it stands for

C = 0.0 ppm/c
0 = -1 (multiplier)
G = 30ppm tolerance over 25-85c temp range

on the other hand adgr your XLR was obviously a typing error and you meant to type X7R which is the same sort of rating but from a different coding system.

X7R
X= low temperature requirement of -55c
7 = high temperature requirement of 120c and
R = +/- 15% tolerance

and you take from that, that c0g is superior (and more expensive than) X7R also you cannot find many large value c0g/np0 caps, they generally top out at 0.47uf/470nf at least for the standard small package leaded and SMD

also adgr: people have been throwing randomly chosen bypass caps at problems for many years so I cant blame you, but it certainly isnt guaranteed to improve matters

Last edited by qusp; 15th May 2012 at 01:41 AM. Reason: reformatted for readability
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Old 15th May 2012, 01:54 AM   #16
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Quote:
Originally Posted by qusp View Post
and you take from that, that c0g is superior (and more expensive than) X7R also you cannot find many large value c0g/np0 caps, they generally top out at 0.47uf/470nf at least for the standard small package leaded and SMD
Great post qusp and thanks Drew for asking a Not So Dumb Question.

I didn't know the ratings system info, I learned something today!
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Old 15th May 2012, 01:57 AM   #17
raul_77 is offline raul_77  Europe
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...about capacitors:

Capacitor Sounds, Speaker Cables and Crossover Inductors.
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Old 15th May 2012, 11:57 AM   #18
PET-240 is offline PET-240  Australia
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Hey Hochopeper,

I learnt in Year 7 at school the sting on a bee is in its bum. I was laughed at but now I knew. Course if you asked them capital cities or their times tables, the blank looks one would get would swear they didn't understand the question......

Indeed learnt much from that, what fascinated me most is.......

That's probably all in his head.........I can remember all sorts of stuff, that I'll need to write down......!

Cheers,

Drew.
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Old 30th May 2012, 11:18 PM   #19
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Default The starting point

After several simulation with different topologies of regulator the following schematic is the starting point to build a prototype.
First stage, rectification and filtering, use a CRC filter to well decoupling regulator from AC.
Second stage is an op amp based series regulator with preregulation using a monolithic IC LT1085. The reference of preregulator is the clean regulated output of the stage, such as in the Jung super regulator. Follows a conventional series regulation implemented by an LT1028 low noise high speed op amp and a classic D44H11. Voltage reference of feedback circuit is an AD780, very low drift 3ppm/C. Op amp is decoupled from power supply with a 0.5 ohm resistor and a capacitance multiplier.
Last stage is a feed-forward shunt section, consisting of an op amp, a mosfet, a capacitor and a few resistors. This stage reduce the noise about 30 db and improve transient response. Based on a Maxim application note, it can cancel noise up to 1.3 mV. Best choise for op amp should be OPA350, but I'm note sure it can tolerate 6V power supply; data sheet indicates 7V as absolute maximum supply voltage and 5.5V max operating voltage.

I'm still working with simulation, then I'll order components to buld a prototype and test its real performances.

Any suggestions are wellcome.
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Old 30th May 2012, 11:33 PM   #20
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I'm going to write some "Cardinal Rules" for regulators:

1) Regulate the clock Vcc/regulator separately from analog circuitry regulation.

2) Load the regulator for as much current as the pass transistor can handle (heat sinked of course.) If you have to, add a ballast resistor to accomplish this.

3) Don't skimp on trace width.

4) where you think you can use a 1/4 watt resistor use a 1/2 watt resistor.

I would take a look at the layout which Jan did for Jung's regulator and go from there.
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