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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KHz

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#761
kuribo said:
Is this going to ship with some sort of manual?

I am still curious as to how three or four boards can be synced to use it with a three or four way active system????
Click to expand...

Søren posted recently that a manual will be ready when the boards ship - he was finishing the firmware for release and would start writing the documentation once that was done.

There was some discussion in this thread about multi-board setups. You'd have to dig back and find the posts.


** Just checked the first post and see that Soekris has just updated it with information that first batch is sold out, and second batch is close to being sold out.
I wonder how many DIY oriented products sell 600 boards in less than 3 hours?
 
Last edited:
#775
TNT said:
So Soren recommends at least / around 10V in post #766 and 2 post later You link to 7V trafos...

//
Click to expand...

Søren has repeatedly said 6-7V and 5W, and said a couple of posts prior to mine that 9VAC is too high.

10V refers to DC voltage - and obviously if you rectify 7VAC to DC you get:

7 x 1.414 = 9.898V DC or close enough to 10VDC

The reason Søren is warning against using 9VAC is that the rectified DC voltage is:

9 x 1.414 = 12.726VDC which is fine while the Trafo is loaded.

But the off load voltage output by the transformer can rise by around 18-23%. The one I linked to has a regulation spec of 18%.

So unloaded:
7VAC x 18% = 8.26 x 1.414 = 11.68VDC
9VAC x 18% = 10.62 x 1.414 = 15.016VDC

Even at 18% off-load regulation the 9VAC secondaries are at the maximum limit of the board.

The 10VAC Trafo you think Søren was proposing:

10VAC x 18% = 11.8VAC x 1.414 = 16.68VDC = toasted Soekris R2R DAC.

cheers
Paul
 
#776
spzzzzkt said:
There is a Farnell part that was suggested by a member:

MCFM50/07 - MULTICOMP - TRANSFORMER, TOROIDAL, 2 X 7V, 5VA | element14 Australia

Element14/Farnell are out of stock.

However, there is a UK based eBay seller who does have stock:

MCFM50/07 Multicomp Mini-Toroidal , 5Va 2X 7V | eBay

I got one from this seller and the transformer arrived in Farnell packaging.
Click to expand...

I will use 15-0-15-0 troidal transformer and this regulator.
4.17uV Ultralow noise DAC power supply regulator +-12/15V 1A - DIYINHK

at the end u get 12v 1A regulated power.
 
#780
spzzzzkt said:
Søren has repeatedly said 6-7V and 5W, and said a couple of posts prior to mine that 9VAC is too high.

10V refers to DC voltage - and obviously if you rectify 7VAC to DC you get:

7 x 1.414 = 9.898V DC or close enough to 10VDC

The reason Søren is warning against using 9VAC is that the rectified DC voltage is:

9 x 1.414 = 12.726VDC which is fine while the Trafo is loaded.

But the off load voltage output by the transformer can rise by around 18-23%. The one I linked to has a regulation spec of 18%.

So unloaded:
7VAC x 18% = 8.26 x 1.414 = 11.68VDC
9VAC x 18% = 10.62 x 1.414 = 15.016VDC

Even at 18% off-load regulation the 9VAC secondaries are at the maximum limit of the board.

The 10VAC Trafo you think Søren was proposing:

10VAC x 18% = 11.8VAC x 1.414 = 16.68VDC = toasted Soekris R2R DAC.

cheers
Paul
Click to expand...

You also need to account for line variation, I typical put that at +- 15%.

So at max 16V DC internal gives: 16 + 0.5 (diode bridge) / 1.15 (high line) / 1.25 (load reg) / sqrt2 = 8.1V
And at min 7V DC internal gives 7 + 0.5 (diode bridge) * 1.15 (low line) / sqrt2 +1 (ripple) = 6.8V

So trafo have to be specified at 2x 7V-8V AC when you account for line and load regulation. But nothing stops you by powering it by a DC power supply....
 
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