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Old 10th July 2013, 09:59 PM   #11
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You could use four of the size 1210 SMD resistors (0.5 watt rating) to get a 330 ohm, 2 watt resistor in SMD. (330R parallel 330R) series (330R parallel 330R) for example.

Four of the size 0805 resistors (0.4 watts) will get you 330 ohms, 1.6 watts. Since you're actually dissipating (15.0 x 0.046) = 0.682 watts, you might deem this margin of safety to be "adequate."

LT1085 and LM337 are available in SMD, and so are the excellent rectifier diodes MURS120T and ISL9R860S.
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Old 11th July 2013, 12:42 AM   #12
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LT1963A/LT3015 --using anything less is like putting dirty underwear on after taking a shower.
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Old 11th July 2013, 07:23 AM   #13
tjencks is offline tjencks  United States
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Default LT1963A/LT3015

Jackinnj,

I'm guessing the combo you mention would be superior to LT3032 due to the faster transient response? As I don't believe the noise figure is as good. It looks as though these puppies have a lot more current capability than I'd need.

As for the application of all of this. I've built 5 Randy Slone Totem Pole amps for my home theater and have been having a tough time eliminating all the grounding hummm...

I've got it to a point where its not audible while sitting on my couch...but putting the ear to the speaker I can still hear it and its bugging me. So figured by going to a grounded connection to my Marantz 8801 may help a tad.
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Old 11th July 2013, 11:35 AM   #14
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Quote:
Originally Posted by gmphadte View Post
Better use 317L/337L

Gajanan Phadte
The idle current issue u mentioned at post#5 is for the 317T and the one I mentioned are low current versions with L suffix which supply 150mA current instead of the 1.5A for the T version. Just to clarify

Anyhow, a shunt regulator is preferred over these.

Gajanan Phadte
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Old 11th July 2013, 12:57 PM   #15
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Quote:
Originally Posted by tjencks View Post
Jackinnj,

I'm guessing the combo you mention would be superior to LT3032 due to the faster transient response?
They surprised everyone by how well they performed in the great regulator bakeoff.

One of the best regulators for transient response is the Belleson -- but it's sound quality was assessed as "middling".

Noise was the least correlated factor when judging sound quality.
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Old 11th July 2013, 05:01 PM   #16
tjencks is offline tjencks  United States
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I suppose I should read the regulator bake off.
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Old 11th July 2013, 05:03 PM   #17
tjencks is offline tjencks  United States
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Any suggested shunt circuits out there other than the Salas?
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Old 11th July 2013, 06:47 PM   #18
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Originally Posted by tjencks View Post
Any suggested shunt circuits out there other than the Salas?
Walt Jung advocates modifying his "Jung Super Regulator" to a shunt topology (link to audioXpress interview), schematic on page 6.

Me, I'd probably start with something plain and simple like the attached. (Negative regulator would be the mirror image, more or less). You may decide to replace the single LED with a series string of several LEDs, to meet Walt's guaranteed start-up criteria: voltage dropped across string is larger than the reference voltage across IC1.

I've suggested puny transistors with low max-power specs, for this application whose load current (6 - 7 mA) is known to be low. Higher output current would need beefier transistors.
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Last edited by Mark Johnson; 11th July 2013 at 06:50 PM.
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Old 11th July 2013, 07:31 PM   #19
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R4 is not necessary. With RRO opamp, LED (D3) can be left out or replaced with small resistor. And CCS made from single BJT is not my cup of tea, nor LM329 as Vref.
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Old 12th July 2013, 08:32 AM   #20
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Don't think too much on which shunt regulator as your circuit does not demand it. If it was a phono preamp, story would be different.

Any costly exotics will give you small improvement proving the law of diminishing return.

Gajanan Phadte
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