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zei 29th August 2008 06:48 PM

Pass D1 I/V Stage PCB
Hi everyone.

I,m redoing the outputstage on my DAC (opamp based) And of course Mr Pass,s D1 I/V is one the i want.. :)

Soo,, to the drawing board... This is the result. Schematic found somewhere on the Net and layout ideas stolen a little bit here and there.... :cool: :angel:

Anyhow, I need your eyes to see if there are any mistakes.
I,m going to have some boards made and don,t want to buy PCB,s that do not work ... :)

Yez, i have got an ok from Master (if anyone wondered.) :)



Thanx !


khundude 29th August 2008 09:22 PM

I have no ideas about the I/V. However, if you build a real D1 I/V clone I would be very interested in buying some boards from you. I am looking for the original Pass D1 I/V. I hope this is what you are trying to achieve. I will keep posted.

zei 29th August 2008 09:37 PM

mmm i can see the schematic does,nt work.

here it is..

Thanx khundude


steenoe 30th August 2008 07:37 AM

Hi Zei
Except for R21B should read 100k, your schematic is fine. I take it that the trimpots are 20k.
I will go over your board later. What is the size of your board?
If you plan to use screw terminals for the outputs it would be a good idea to make 2 holes for standoff's in the output end for support when tightening the terminals. Just place them as close to the sides as possible. Nice work BTW.


zei 30th August 2008 07:53 AM

Thanx Steenoe!

Good eye spotting that resistor :)

Board size is about 50X60mm. My ide was to use output Caps offboard to due to size. Me and my friends might use different sorts.

I added the Screwterminals just to have that option when testing everything ;) Mkaes everything sooo much easier...

I,m alos going to redraw some wirds to tidy it up a bit.

Thanx Again!

Loking forward the the verdict on layout:)


steenoe 30th August 2008 08:03 AM

You are welcome.
When cleaning up; take a look at the tracks between R18B-R19B and C4+-Q1 drain.
From the pic, it looks like a little zig-zag'ing is going on there.
Hardwiring the outputcaps offboard is fine to keep a nice compact board size.


zei 30th August 2008 06:31 PM

I was thinking of usin a "standard" LM3x7 PSU to start with and then maybe use something like ZenMod,s Shiny...

Would i gain anything from changing to the Shiny? besides the obviuos coolness.. :cool:



zei 30th August 2008 06:58 PM

Thanx Steenoe for that sharp eye.. Here is a new image of that layout.

More comments before i send the files to PCB factory...?



steenoe 30th August 2008 07:10 PM

Hi Zei.
Just finished going through all the connections on the board and it seems to be perfectly fine. JP2 is underneath C9 and that is probably not the best place to have a jumper. If you wanted to, it looks like C9 (and C4 for board symmetry) could be moved closer to the middle and in the proces expose JP2's solderpad.
It would be nice if at least one more could do a little checking. 3 sets of eyes see more than 2.
I was going to ask you what you had in mind for the PSU. As far as I recall, the Shiny is a shuntreg? Could you post the schematic or link to it? A shuntreg is possibly the best choice, but it takes some calculating to get it right. Approx. 20mA excess current must run through the shunt element and the ccs must provide that on top of what the circuit draws, itself.


zei 30th August 2008 07:22 PM

Thanx again steenoe.

I,ll look inte our suggestions right away and the post a new image.

Regarding the PSU, I have no clue on calculatin it whatsoever. .so i was kinda hoping for some help in that area..
Here is where i found it Shiny Link :)


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