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Old 29th April 2013, 09:26 AM   #2891
qusp is offline qusp  Australia
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I wouldnt worry about trying to please batchPCB, afaik they have recently shut their doors, or minimum changed their supplier who is much more expensive, apparently higher spec process, but priced enough higher to make it not really worthwhile when there are other services around.

great work on the documentation btw! really excellent, I prefer the SMD version and i'm looking to use more dual parts to get the size down and with 4 layer boards so cheap now, if going for small size and high quality, it just makes sense to use 4 layer. obviously its not then possible to make at home, nor as widely accessible, but thats OK for me.

one thing though and this is half question, couldnt you go up a couple sizes for trace width on critical low noise and power supply traces?
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Old 29th April 2013, 09:34 AM   #2892
Variac is offline Variac  United States
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If you want them to bolt onto the new base plates and riser plates of the new diyAudio chassis' then the mounting holes should be in a multiple of 10mm in each direction, ie: 20x40, 30x40 50x50, 50x70, that sort of thing. The plates will have a grid of holes at 10mm centers in each direction. This is different than the heatsink UMS.

The Dangerous Prototypes/Sick of Beige SQUARE shapes are all just fine..
And our chassis' are FAR FROM BEIGE!

Last edited by Variac; 29th April 2013 at 07:18 PM.
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Old 30th April 2013, 02:55 AM   #2893
rsavas is offline rsavas  Canada
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Is there anything like a tutorial on how to administer a group buy?
I have no idea.
Quote:
I haven't seen a real paycheck in 6 months, so I'm not in a position to absorb the front-end costs of creating a stockpile to be sold over many months or years.
I am in the same boat, pay cheque wise, so I understand!!
I guess that will have to get our own fab'd.
Thanks Dale for the sim stuff and all your hard work
Rick
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Old 30th April 2013, 05:48 AM   #2894
Variac is offline Variac  United States
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If everyone's onboard with this design and gives it their blessing , including Scott who seems swallowed up by his day job, and the mounting holes fit the "multiples of 10mm" standard, then diyAudio could order a batch. We've made various boards which have come out of thread collaborations, and are still refining the process..

Here's our latest thoughts:
We list it in the store as "backordered" People order and pay for whatever number of boards they want, we then have them made at a good price, better if more are ordered. When they come in, the store then automatically sends them out. Now they would be "beta" at this stage and we can't be held responsible if they need reworking or something. Pretty seamless if people are really interested.

Mark

Last edited by Variac; 30th April 2013 at 09:26 PM.
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Old 30th April 2013, 08:40 PM   #2895
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Mark
I think that your suggestion sounds like a good idea, provided that you give some free PCB's to Dale (dchisholm), 25 free pcb's sounds like a fair suggestion.

Stein
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Old 1st May 2013, 04:56 AM   #2896
Variac is offline Variac  United States
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I think that Dale can decide for himself what is fair.

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Mark
I think that your suggestion sounds like a good idea, provided that you give some free PCB's to Dale (dchisholm), 25 free pcb's sounds like a fair suggestion.

Stein
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Old 1st May 2013, 04:59 AM   #2897
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Originally Posted by qusp View Post
. . . I prefer the SMD version and i'm looking to use more dual parts to get the size down . . .
Yes, I'd like to look at multi-device packages on the SMD version. My objective of getting down to the API2520 footprint didn't have much support but I'd like to give it a try out of principle. Motivation and interest have been lagging for several months. Knowing that there won't be a budget to construct anything I design doesn't help.

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. . . go up a couple sizes for trace width on critical low noise and power supply traces?
I think every trace on the latest (THD) PWB is 15 mils. That wasn't an entirely arbitrary value:
  • I chose a value that was within reason for home fabricators
  • On the patterns I used for TO-92 and SOT23 devices, a 15 mil trace can be routed between pads and meet "balanced" 15 mil trace/ 15 mil space constraints. (The TO-92 pattern itself has it's own trace/space problems, but that's another topic.)
  • A quick eyeball scan of the PWB seems to show that, except for the segments running between transistor pads, traces can be universally increased to 20 mils or even 25 mils, though several segments will need to be nudged around or re-mitered to meet clearance constraints.
Instruct me on this, especially the "critical low noise" traces. According to my intuition:
  • The only critical low-noise nodes are the gate leads on the input BF862 pair. The signals in the drain-source circuit of these devices have already been boosted well above device noise by the transconductance of the input devices.
  • Trace width shouldn't have significant influence on noise performance. If anything, wider traces will increase stray coupling capacitance and increase noise susceptibility.
But as they say, "What you know that just ain't so can kill you.".


For power traces, my thinking is based on:
  • Except for the output devices, no trace or component carries more than 10 mA, maximum.
  • By conservative PWB layout criteria, a 15 mil trace can carry 1 amp without compromising electrical performance. That gives 99% margin between operating levels and trace rating.
  • The output transistor collector-emitter circuits might carry as much as 50 mA (high output drive version). This is still 95% margin but I will increase these traces to 25 mil or more on the next rev.
Give me some more specific guidance on what I need to change!

Dale
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Old 1st May 2013, 05:05 AM   #2898
qusp is offline qusp  Australia
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honestly I think it would be pretty hard to compete with the likes of iTEAD unless you use the bulk buying power to get 2oz copper, gold plate (neither really needed) the current format we can get 10 pieces 100x100mm for $24 total

as far as the changes you pretty much covered it, the input and output nodes. the thinking comes from clock circuits, the wider the trace (within reason) the better. and I dunno, I just tend to follow that where I can, when it doesnt cause layout compromises I use signal traces that equal the pin size and I prefer power planes to power traces for low impedance. its just how I roll, the comment was meant to encourage discussion not say my way is better.

i'm pretty darn sure that we can throw together and manage you a couple parts kits and PCBs for your trouble...

Last edited by qusp; 1st May 2013 at 05:13 AM.
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Old 1st May 2013, 06:41 AM   #2899
RNMarsh is offline RNMarsh  United States
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being broke is no fun at all... I can kick in some funds to get it going.... thru hole version.
drop a note to me if I can help.


Thx-RNMarsh
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Old 6th May 2013, 06:52 AM   #2900
RNMarsh is offline RNMarsh  United States
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Originally Posted by RNMarsh View Post
being broke is no fun at all... I can kick in some funds to get it going.... thru hole version.
drop a note to me if I can help.


Thx-RNMarsh
Been quiet too long.... What's the status?

-RNM

Last edited by RNMarsh; 6th May 2013 at 06:53 AM. Reason: SUP?
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