[PeterR]

Quote:

Originally Posted by BCBill If R22 on my _alternative_ schematics is changed from 1K to 10K and if the 47pF beside it (C7) is deleted, they may _finally_ represent the group-buy PCB.

I think so. The 1k resistor should have gone in series with the input, BTW. There are no provisions on the board for those two parts of an input network, but it still
wouldn't be that hard to add them...

 

[rsaavedra]

Quote:

Originally Posted by PeterR There are no provisions on the board for those two parts of an input network, but it still wouldn't be that hard to add them...

Obviously you guys have applied your keen vision and scrutiny onto the minute details of the schematics and diagrams. How "not hard" will it be to deal with these issues you've mentioned? Or actually, do you mean we will have to use some hookup wires and keep some components kind of floating in the air to really close the circuit as it should be? E.g. the PCB won't really have all the needed connections between components on the board?

I haven't inspected anything in detail yet, but after your comments I'm not sure if populating the boards properly will be more tricky than straightforward.

 

[rsaavedra]

Boards delivered!!! Will go home soon before the administration of the building closes to make sure I can post pics today.

 

[randytsuch]

Quote:

Originally Posted by PeterR I've just taken a look at the Gerber files - the "mystery" resistor goes from input to ground, setting the input impedance.

Hi Peter,
Thanks for looking at the gerbers, and clearing that up. I don't have a gerber viewer.

Bill,
I would agree with leaving that final input tweak out. Seems like it is something you could try adding later, if you want. Kevin did not think it was important enough to add to the PWB, so I don't think it is a big deal.

Now, I can go order some parts

Randy

 

[rsaavedra]

Couldn't wait, went home quickly to pick up the package, shoot some pictures and post them here:


Right after removing the thick layer of foam beads:

They come in little wrapped bricks of 25 boards each. That makes 175, maybe they sent one extra for free, haven't counted the 7 packages in detail, just one since I took the pics and came back to the office quickly:

Here the top of the board, still in the plastic wrap:

Here the seven packets:

Here's the invoice. Smart me I placed a pen on the address for security, and missed my credit card on the bottom left whose last 4 digits were printed, only now I realized that was there. Just covered it using Window's XP Paint. Btw as you can see, shipping from PCBNet to me was exactly $20:

Opening one of the packets:

Here both sides of the boards with a ruler on top:

Ain't that pretty?

 

[PeterR]

Quote:

Originally Posted by rsaavedra How "not hard" will it be to deal with these issues you've mentioned? Or actually, do you mean we will have to use some hookup wires and keep some components kind of floating in the air to really close the circuit as it should be? E.g. the PCB won't really have all the needed connections between components on the board?

No, everything you need is on the board, that input filter is optional and probably not necessary. If you want one, you could solder the C directly to the 10k resistor in the middle. Then solder one end of the 1k resistor to the input pad, the other end of the resistor is now your input. Shouldn't get too messy.
Quote:

Originally Posted by rsaavedra Boards delivered!!!

 

[rsaavedra]

Quote:

Originally Posted by PeterR No, everything you need is on the board

Ah ok great, thanks Peter, I was worrying too much then.

 

[TrevorNetwork]

They look great!

Will you ship next week? Are we having a PSU / HS / FET groupbuy as well?

 

[rsaavedra]

Quote:

Originally Posted by TrevorNetwork They look great! Will you ship next week? Are we having a PSU / HS / FET groupbuy as well?

Certainly I'll start shipping on Monday. Came back home, here two more pics in a slightly larger size for more detail:

I compared the thickness of the bricks of boards putting them next to each other (and keeping an eye on the thickness of the bubble wrap side of the wrapping, which can be misleading). One of the unopened bricks is thinner and has 24 boards, all the others are same thickness having 25. So we have exactly what we ordered: 174 boards.

 

[ayt999]

cool.

thanks for the pictures.

 

[hegestratos]

Quote:

Originally Posted by Glassman still working on Blue Hawaii so no dynahi psu yet.. talking to someone here in diy section we came to a conclusion that default jung reg should work just fine.. the boards are available here.. you will need two of these boards and some bigger heatsing to bound those two TO220 parts to.. also you'll need to build a rectifier bridge and some big capacitors on a breadboard to put before those regulators.. or you can ask aos to redesign the boards such that this rectifier will sit together with two regulators on single pcb..

Don't forget the current source must be adjusted too. Let's assume D44H11/D45H11 pass transistors, a 1.6V LED and ZTX750/ZTX751 transistors. I'll use the names/numbers as in ALW's schematic. There will be a drop of at least 0.35V over R1, so in order to get the 0.05A current we need to get 2A through the negative side pass transistor, R1 must be less than 7 Ohm. That's not a lot. I would suggest replacing the red LED. A 3.4V blue LED wouldn't just look good in a plexiglass case. It would also give 2.15V over R1, making it 43 Ohm.

I haven't looked at the amp in detail so I'm not entirely sure about the power requirements; I think KG mentioned 28V 1A supplies. So this should give enough power for a balanced amp. For a non-balanced amp you can increase R1 to 86 Ohm so it supplies at most 1A on the negative side.

About capacitors & heatsinks: a simple estimate shows that with a 30V transformer you'll need some 4000uF capacitance and 20W of heatsinking on either side of the supply for 2A.

Cheers, Alfred

 

[rsaavedra]

Hello Everyone1,

Went to the post office, I asked for options and the most convenient way to ship within the US would be using their small priority mail boxes. If weigth is less than 1 lb. the cost is flat $3.85 anywhere in the US. This I had also verified here initially: http://www.usps.com/consumers/domest...%20flat%20rate

I took two boards with me bubble wrapped, the weigth was 2.9 oz, each board then is about 1.5 oz. The post office employee suggested that I use cardboard layers between and outside the boards, then bubble wrap that bundle, which sounded like a great idea. With the cardboard layers, I estimate 8 - 10 boards will still be within 1 lb limit. Under 2 lbs, UPSP link above indicates the cost varies from $3.95 to $5.75 depending on zone.

The cardboards layers I can make from older boxes, but I have to buy enough bubble wrap. Instead of arbitrarily charging let's say $4.00 instead of $3.85, I'll purchase a bubble wrap roll, and will divide the cost by # of boards. This will be almost ludicrous, but so that we all pay exactly our total costs. Another thing: you all paid $5 per board for bill #1, but their cost eventually became $4.20, so all of you have a positive balance from bill #1.

Shipping from PCBNet to me was $20.0, that divided by 174 boards == $0.11 per board.

So for all of you in the US and with less than 10 boards ordered, I'll send Paypal payment requests for your Bill #2, the amount will be

[size=small]Bill#2 = Rate + (0.11 + bubbleWrap/174)*#boards - (your positive balance from bill#1)

Where Rate == $3.85

[/size]

The 10-12 board cases might be a little more if the bundles go above 1 lb, I'll let you guys know tomorrow.

For international addresses: One of you groupbuyers in Germany suggested to use the "Large Flat rate" USPS envelope, which has a flat rate of $9 if within 1 pound. I just checked here and that rate applies also to Japan, Norway, and the UK. Canada's rate is $7. Using the small envelope rates go down to $5 and $4 respectively. Your bill#2 amount will be same formula as above, but rate will be your specific international rate.

Cheers,
Raul

PS. In fact, after applying the formula it turns out I owe some people money. Those who are in the US and ordered 6 or more boards have a positive balance from bill 1 larger than the final shipping charges. In those cases, instead of a payment request I will be sending you what I owe you.

 

[raif]

Quote:

Originally Posted by rsaavedra PS. In fact, after applying the formula it turns out I owe some people money. Those who are in the US and ordered 6 or more boards have a positive balance from bill 1 larger than the final shipping charges. In those cases, instead of a payment request I will be sending you what I owe you.

you can save yourself the trouble and keep mine.(the money not the boards

)

 

[h3nG]

seriously...i am sure it's not that much. your time is probably worth a lot more than the chump change.

 

[intlplby]

you can keep it or donate it to head-fi- your choice


thanks for letting us know though