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Old 22nd April 2011, 04:45 PM   #671
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Originally Posted by NYCOne View Post
Thank you for your interest and guidance to me, and the forum.
Yes, nelson is da man.

Hereby my schematic sofar, should look pretty familiar except maybe for the current sensing resistor setup which I picked up from the pass d thread. As far as I understand it allows for the load (from bdx into 4700 cap) and unload (from buffer cap into IRFP) currents to be separated from each other, a bit like push-pull magic.

Click the image to open in full size.
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Old 22nd April 2011, 05:09 PM   #672
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Originally Posted by chriscam View Post
Both schottky's and mosfet are of the fully insulated types, i.e. the backplate is covered in plastic and allows mounting without the regular mica wafer. While at the subject, could you tell me what the thinking is behind those ceramic pads ? What's their advantage over standard isolation wafers ?
I only mentioned ceramic because that's what I use (not your regular stuff but a ceramic-based 2mm thick material I get from a friend).
In general, and based on my experience with switching amplifiers, it's recommended (and I'm quoting from Tripath's Application Notes 17 - "DO’S AND DON’TS WHEN DESIGNING FOR EMI COMPLIANCE"):
Quote:
...where external MOSFETs are required, use low dielectric constant insulators to prevent the switching noise from coupling onto the heat sink. Aluminum Oxide insulators or polyester film thermally conductive insulators (such as Poly-Pad K-10 from The Bergquist Company at Thermal Interface Material, Thermal Management ~ The Bergquist Company) can be used with the MOSFETs. Both of these insulators reduce radiated EMI from the chassis.
Moreover, quoting from Tripath's AN11 ("DESIGNING FOR EMI REGULATORY COMPLIANCE"):
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The use of thicker insulators under the output FETs has been shown to be very effective at broadband suppression.
Hope that helps.

Last edited by TheShaman; 22nd April 2011 at 05:19 PM.
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Old 22nd April 2011, 06:19 PM   #673
NYCOne is offline NYCOne  United States
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Originally Posted by osscar View Post
NY - very nice DIY case - i like those immersed bolts!
Thanks for the props, but I didn't build the case - I don't have any real tools (I finally bought a drill press of PCBs and a router to make OB speakers). I'm about to post a how to thread on building your own. I'll post all the sources in that thread.
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Old 22nd April 2011, 07:17 PM   #674
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Originally Posted by chriscam View Post
Would you like to comment on the use of a switched current source to half dissipation ?
As in a switching amplifier with a high output impedance?

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Old 22nd April 2011, 08:08 PM   #675
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Originally Posted by Nelson Pass View Post
As in a switching amplifier with a high output impedance?
I was referencing this thread were QED047 suggests to replace the current source with a self oscillating bucket switcher.
Quote:
Originally Posted by QED047
The inductor takes time for the current to build when it is "in circuit" (storing power as a magnetic field). The transistor switch keeps on connecting and disconnecting the inductor to maintain a controlled current about the set-point. The inductor returns "unused power" via diode at the open switch to the +v rail. Using this arrangement there is (theoretically) no power loss in either the inductor or switching transistor, yet there is a DC current flowing across a DC voltage!
The proposed setup :

Click the image to open in full size.


Not only would Zen efficiency rise 50%, it would also lower my electricity bill while maintaining the wonderful sound. And TheShaman, thanks for the explanation ! I'll keep that in mind when I start playing around with the bucket switcher.

Last edited by chriscam; 22nd April 2011 at 08:16 PM.
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Old 22nd April 2011, 08:53 PM   #676
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Quote:
Originally Posted by chriscam View Post
I was referencing this thread were QED047 suggests to replace the current source with a self oscillating bucket switcher.


The proposed setup :

Click the image to open in full size.


Not only would Zen efficiency rise 50%, it would also lower my electricity bill while maintaining the wonderful sound. And TheShaman, thanks for the explanation ! I'll keep that in mind when I start playing around with the bucket switcher.
Hey Guys, What happened to the pictures?
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Old 23rd April 2011, 12:38 PM   #677
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Originally Posted by WithTarragon View Post
Hey Guys, What happened to the pictures?
Ooo shoot, sorry, got a bit distracted by all these pics from energy wasting currentsourced heatsinks, I'll start a separate thread.
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Old 23rd April 2011, 04:56 PM   #678
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Originally Posted by chriscam View Post
Not only would Zen efficiency rise 50%, it would also lower my electricity bill while maintaining the wonderful sound.
If it maintains the wonderful sound, then I'm all for it.

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Old 24th April 2011, 12:13 AM   #679
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Originally Posted by d to the g View Post
I'm running a miniA in my garage off a pair of 12V 6A switchers (apex jr for $8/pc) but I threw in a tiny RC filter afterward. I felt that a 1000uF cap cleaned it up a lot.
Should try a toroidal instead much cleaner.

I love my smd minis....
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Old 30th April 2011, 10:57 PM   #680
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I made this.

Whit help

And Papa design.

Tanks...
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