pinkmouse said:Your silkscreen notations for the jumper settings will end up as indecipherable blobs, they are way too small and too fine.
Does that qualify me as a beta tester?
Good point.
The PCB Fab says they are within spec, but we will leave the documentation for jumper settings here and on our site so if people get blobs we won't be out of luck.
If you want in on the test then your in.
Cheers!
Russ
Shhhh!
It's ok, I just printed everything out on the works printer for later perusal!
Oh, and anther quick point, can you move the component designators out from under the footprints? It makes fault finding so much easier. Not a great problem with the number of components on this board, but a good habit to get into.
It's ok, I just printed everything out on the works printer for later perusal!
Oh, and anther quick point, can you move the component designators out from under the footprints? It makes fault finding so much easier. Not a great problem with the number of components on this board, but a good habit to get into.
I know I am late The input stage could use some refinement IMHO. I would load the primary side after the cap with 150 Ohm and I would load the secondary side with 150 Ohm too. Definitely keep the input cap, it protects the pulse transformer from DC. A 10 kOhm from the SPDIF-2 to GND wouldn't hurt, it will keep the primary side at low potential when switching cables with the DAC powered on. I used this circuit a lot ( also for inspiration ) but please note that it uses a 1:4 transformer:
http://members.brabant.chello.nl/~m.heijligers/DAChtml/dig_r2a.pdf
*It is adviseable to use a 75 Ohm BNC chassis connector directly on the PCB for optimal results as standard PCB connectors really aren't suitable 75 Ohm devices. Please see the DAC Peter Daniel designed to see what I mean. The circuit with SN75179 also works well but IMO the guideline with semiconductors is that "less is more"....
When I was searching for the right thread I stumbled upon this one that I did not try ( to me both the caps and the 10 Ohm resistors at the secondary side seem useless but I may be wrong ) but you'll get the idea:
The input stage could use some refinement IMHO. I would load the primary side after the cap with 150 Ohm and I would load the secondary side with 150 Ohm too. Definitely keep the input cap, it protects the pulse transformer from DC. A 10 kOhm from the SPDIF-2 to GND wouldn't hurt, it will keep the primary side at low potential when switching cables with the DAC powered on. I used this circuit a lot ( also for inspiration ) but please note that it uses a 1:4 transformer:http://members.brabant.chello.nl/~m.heijligers/DAChtml/dig_r2a.pdf
*It is adviseable to use a 75 Ohm BNC chassis connector directly on the PCB for optimal results as standard PCB connectors really aren't suitable 75 Ohm devices. Please see the DAC Peter Daniel designed to see what I mean. The circuit with SN75179 also works well but IMO the guideline with semiconductors is that "less is more"....
When I was searching for the right thread I stumbled upon this one that I did not try ( to me both the caps and the 10 Ohm resistors at the secondary side seem useless but I may be wrong ) but you'll get the idea:
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jean-paul said:
Your in,
Let, me see what I can do about your suggestions.
Keep in mind I did not anticipate the PCB being directly mounted to a chassis, so I have not provided for PCB mounted BNC or RCA. Instead I was going to allow for chassis mounted connectors which would be wired to the PCB via the terminals. This may not be optimal, but it is very practical...
Cheers!
Russ
BTW I am reworking the silkscreen(had some flubbage) and layout a bit based on the input so far.
Jean Paul,
I think I can work it so that we have a PCB mounted BNC, those who do not want to mount the PCB to the chassis can simply wire to the pads, or I may have alternate pads for the terminal block.
I will post the changes tomorrow.
Jean Paul,
I think I can work it so that we have a PCB mounted BNC, those who do not want to mount the PCB to the chassis can simply wire to the pads, or I may have alternate pads for the terminal block.
I will post the changes tomorrow.
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