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Old 27th May 2007, 11:12 AM   #1
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Default Legal advice please (!)

Hi,

I have a couple of schematics of commercial gear (high power SS amplifiers) that might be of interest to the group.

What's the legal position regarding publishing them here?

As far as I know there's no problem with DIY clones; does anyone know different?

cheers

Chris
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Old 27th May 2007, 12:03 PM   #2
peufeu is offline peufeu  France
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Selling stuff that infringes on someone else's patents will get you in trouble.
However, building anything you want for personal use is perfectly legal.

Access to patents is unrestricted, patents are public, to facilitate research.

So, if you have not signed a NDA with the manufacturers, then post the stuff ; we're interested
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Old 27th May 2007, 01:15 PM   #3
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Quote:
Originally posted by peufeu
Selling stuff that infringes on someone else's patents will get you in trouble.
However, building anything you want for personal use is perfectly legal.

Access to patents is unrestricted, patents are public, to facilitate research.

So, if you have not signed a NDA with the manufacturers, then post the stuff ; we're interested
Thanks, Peufeu, pretty much what I thought.

The amps are C Audio ST600 and SRX3701; 600 and 900W respectively. The ST600 is an unusual design - basically a 5524 driving 4 pairs of lateral MOSFETS with the sources commoned to chassis (hence improved heatsinking) and the 'hot' output taken from the centre-tap of the transformer, with an independent secondary supplying the opamp.

I'd have thought the 5534 would have a hard time driving the capacitance of all those FETs but despite that, and the fact that the reservoir caps total 4700uF per rail, the amp is well regarded in terms of sound quality and reliability (from what I gleaned from Googling).

The SRX is a high-current monster with five pairs of BUZ90*D 16A 250W TO3 FETs and 100V rails.

The schematics I have aren't clear enough to be scanned, so I'll re-draw them and post them as PDFs.
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Old 27th May 2007, 01:33 PM   #4
SY is offline SY  United States
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The issue probably isn't patents, but rather copyright. If it's not your drawing, you don't have the right to distribute and post it. Now, if you redrew it yourself, that's a different story, a circuit can't be copyrighted, just the drawing of it.

Disclaimer: I am not a lawyer and my familiarity, such as it is, is with US law.
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Old 27th May 2007, 01:37 PM   #5
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If it says "Copyright 2007 by XYZ Corporation. May not be photographed, copied or reproduced by any means electronic or otherwise, except with the expressed written permission of XYZ corporation" Then they have an enforceable copyright.

If they have the above language on a schematic or manual you've been forewarned.

If they filed a patent, then most of what you need is going to be in the patent filing -- this is why a lot of interesting stuff uses trade-secret protection -- you don't want the kimona lifted too high. Some of the work of noteable posters on DIYAUDIO can be found at the USPTO using the IN/ (inventor) or AN/ (assignee) search tools.
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Old 27th May 2007, 01:52 PM   #6
djk is offline djk
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"lateral MOSFETS with the sources commoned to chassis"

Sounds like the Hafler Transnova, but with an IC rather than discrete transistors.

QSC is the same with BJT outputs.
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Old 27th May 2007, 02:56 PM   #7
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Default Having not the factory data written into the document


Than you can post...also do not give us guarantee that the schematic corresponds, for instance, to model XYZ.

You can post and inform that "someone told" you that seems to be XYZ.

Some innocence sometimes is needed....the same innocence factories deserves to you when they sell you equipments without inform what is inside.

Can be a stone?

If you ask them, for the schematic, your rigth!...they will tell you, with enormous "inoccence" that they never realised that someone would need that....that they have Oficial Repair shops and so on.

You can also use that "inocense", telling that you never realised that XYZ schematic belong to them.

Having nothing written over or under...the schematic "seems" that have not an owner...also seems to them that you are not interested in schematics when you buy audio systems.

Without signed under...no reference of property...it is a "public dominium" material....or...paper with ink only... legally....in our special sittuation...just binary codes.

regards,

Carlos
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Old 28th May 2007, 02:26 PM   #8
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Here's a schematic for a 900W amp. 100V rails. Enjoy!
Attached Files
File Type: pdf 900w.pdf (27.8 KB, 118 views)
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Old 28th May 2007, 02:38 PM   #9
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B-N,

thanks for drawing and posting, anxious to see the Edinburgh chip input amp.
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Old 28th May 2007, 02:44 PM   #10
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Interesting schematic Bootstrapping the folded cascode. No output source resistors?

What's D13-D14 (9V1) for?
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