Group Build: Dynafet

[DigiPete]

[luvdunhill]

Jacob:

I talked with pcbfabex and my suspicion was correct with regard to the silk screen issues. Minimum is 6 mil, if it's less than that they try to resize it, which as they said, often results in fail. They said maybe even go up to 7 mil. This applies for the lines as well as the lines that compose the text. I'm not sure what 7 mil corresponds to in "font size" ... who knows.

Everyone else:

I'm going to talk with Dan soon and we're going to need people to firm up their board quantity. Probably best to do this via PM, so be on the lookout for this.

I've talked with four places, all seem very eager for my business. I have two more board runs to bundle with this, so I'm trying to leverage all of them to get us the best cost, and to finalize the quote I'll need to firm up numbers, hence request for participation.

Specs I'm looking at are 0.062" FR4, RoHS gold immersion, black solder mask, 2 oz copper. Any suggestions with regard to fab choice or specs would, just let me know. Obviously I'm comparing the "standard" options as well, but from what I'm seeing so far, they are pretty much throwing in these "upgrades" due to the volume and new customer status.

[Smeggy]

Cool, sounds great. Shame these get hidden inside cases

[luvdunhill]

Cool, sounds great. Shame these get hidden inside cases

don't they make clear wood?

[Smeggy]

I'm still waiting for them to release transparent aluminum...

[DigiPete]

AMB has some

[luvdunhill]

Looks like $12.50 per board is the magic number, made to the above specs. Dan charges $10 + shipping per board for the other Dyna- boards, as a comparison price point.

This includes parts and shipping for two prototype boards, shipping from myself to Kevin and the initial run of the prototyping boards. This prototyping cost will be split up over the entire number of boards ordered, including Jacob's SMD only version. The divisor at the moment is 88 boards.

Price is ultimately determined on the final number of boards ordered, so be noodling on that one.

[Icarium]

http://spreadsheets.google.com/ccc?key=pPx9B-HzYy0covm0CZGJUEg&hl=en

Please check this spreadsheet and reconfirm the # of boards that you are allocated to on here and confirm whether you want the dynahi compatible boards or the j4cbo build boards.

The difference between the two is the j4cbo boards are slightly smaller and not compatible in most dynahi builds they are more smd oriented and will have a microcontroller for various temperature/current sensing features and possibly some others as well.

We will be doing two separate board orders one for each group.

The j4cbo board group is: Me/j4cbo/atothex/morphsci/pfkman23/naamanf/digger945.

The rest are marked down as dynahi compatible people.

Let me know! Then it will be time to collect money and get boards going.

[j4cbo]

I will be posting details on my version of the board very soon (tonight).

[luvdunhill]

I will be posting details on my version of the board very soon (tonight).

cool! Is it possible then to utilize the 1x4 SIP header and the locations for the current sensing resistors on the prototyping board for anything, or are they more or less unusable?

Icarium: Team vvs_75 requested 10 boards via PM, looks like you need to update their numbers.

[Pars]

<snip>

Specs I'm looking at are 0.062" FR4, RoHS gold immersion, black solder mask, 2 oz copper. Any suggestions with regard to fab choice or specs would, just let me know. Obviously I'm comparing the "standard" options as well, but from what I'm seeing so far, they are pretty much throwing in these "upgrades" due to the volume and new customer status.

Any reason for 2oz copper? Better heat dissipation or better solderability? Also, black solder mask? Ewwww....

Who are the fabs you are considering?

[Smeggy]

Any reason for 2oz copper?

Ah, I see where you're coming from... yes, we need moar! Insist on 4oz copper, just to be safe.

[luvdunhill]

Any reason for 2oz copper?

amb uses it for the beta22 boards

[Icarium]

Think we are leaning towards golden phoenix at this time. Plz confirm peoples! Yes yes certain things are out of date with info that has been provided to me.. I'll probably update tonight. Been busy/tired lately.

[luvdunhill]

amb uses it for the beta22 boards

... and low impedance

[n_maher]

My vote would be imagineering for the pcbs. I wouldn't cheap out on the boards, it seems penny wise, pound foolish to me.

[luvdunhill]

My vote would be imagineering for the pcbs. I wouldn't cheap out on the boards, it seems penny wise, pound foolish to me.

Yeah, I agree it's a hard choice, and it hasn't been set in stone. The cost differential is pretty high, almost 2x, as I can leverage the fact I've done a decent amount of business GP. At this point we really need numbers to be able to go any further.

[DigiPete]

What's haps?

[Icarium]

Boards Final

Here's the final spreadsheet for boards. People in bold are the people i"ve heard from specifically confirming numbers. The rest of you should confirm as well! I'm sure most of you aren't going to change in #s and are in, but think about if you want some extras for just in case.

Let me know thanks!

[Icarium]

Just in case being in case 1 or more of your boards blow up. Getting replacements may be tricky... Well consider yourselves all warned!

[Smeggy]

me = 3

[DigiPete]

Just in case being in case 1 or more of your boards blow up. Getting replacements may be tricky... Well consider yourselves all warned!

Well, if the board blows up, I would demand a refund, as I did not want that functionality in my board

now if parts soldered onto my board blow up, that may or may not be a fault of the board

[j4cbo]

Here's the custom version of the board.

http://b.j4cbo.com/temp/gbf2-custom-top.png

http://b.j4cbo.com/temp/gbf2-custom-bottom.png

http://b.j4cbo.com/temp/gbf2-custom-signal.png

http://b.j4cbo.com/temp/gbf2-custom-sch.png

Notable differences are:

- Most resistors are surface mount. Some are still through-hole, for power and ground plane integrity reasons. According to Marc's dissipation, all the small 0805 resistors dissipate well under 100mW, so there should be no heat issues because of this change.

- The rail capacitors near the outputs are rail-to-ground, not rail-to-rail. This lets you use only one type of large capacitor, rather than two different voltages; the net effective rail capacitance should be close to the same.

- There is no provision for mounting against an angle bracket. The transistors are right up at the edge of the board, for mounting directly to a heatsink. Note that you may want an external heatspreader anyway. This makes the board somewhat smaller.

- There are pads for an onboard relay to select between feedback points. This probably shouldn't be changed while the amplifier is running and headphones are connected.

- At the bottom of the board, underneath, is sensing circuitry for monitoring voltage, current, and output servo position. This is connected to pads for an Atmel ATtiny24/44//84 microcontroller. There are no programming headers for the microcontroller; the chip must be preprogrammed or used with a chip clip, such as this. The relay is also connected to the microcontroller. I can help people with this part but only to a very limited degree - don't count on it unless you know someone who can do AVR programming.

- Pads for a Dallas Semiconductor digital temperature sensor (DS18B20 / DS1822)

- A control bus with connectors on opposite sides of the bottom of the board. This allows for daisy-chaining of multiple boards with common 6-pin headers/connectors.

I've tried to make all the changes suggested in the prototyping process to both boards, as applicable, but please let me know if anything looks wrong about it.

I'll be sending Gerber files for the original and custom versions to luvdunhill soon.

[luvdunhill]

- There are pads for an onboard relay to select between feedback points.

jealous

Fantastic work! I sent you a PM just now. Again, nice work!

Since you've gone back to a four point routing shape for the board, what is the board size difference, I suppose I'll need that info for the board quote anyways.

[luvdunhill]

Okay, the numbers are in. I was able to negotiate the final cost down to $10 per board, which I'm rather proud of. This is for both board revisions (there was like a $0.10 difference or something, that I just rounded up and subtracted that from the prototyping costs) and this includes the prototyping costs and a total of four extra boards that were needed to meet numbers.

I guess I will take the payments. If the money is already in your account, there is usually no charge. Otherwise, please add 3.4%, or even better use a PayPal calculator, which I'd prefer that you do to double check my numbers below. I'll be sure to let you know if the amount transferred is correct.

My PayPal account is [email protected]

Deadline is... Friday maybe? Jacob still has a few changes to make, but I think this might just be doable.

Assuming standard PayPal fees, here's what I get:

luvdunhill - $103.30 (US)

naamanf - $51.80 (US)

vvs_75 - $103.30 (US)

digipete - $41.50 (US)

j4cbo - $257.78 (US)

kevin gilmore - $82.70 (US)

looser101 - $62.75 (non-US)

pars - $41.50 (US)

smeggy -$31.20 (US)

digger945 - $144.49 (US)

Icarium - $165.09 (US)

Spain - $270.86 (non-US)

Thanks guys!