Lme49830

[nickarsow]

Thanks Sergan,
Please note the module has no POWER FETS on it , so it has only one ground - analogue. So , my question was should I take some care for that ground or not . I' clear on two grounds , separated commonly by 10R , but the situation is much different with only analogue ground.
Thanks again
Nick

[Segran]

Please note the module has no POWER FETS on it , so it has only one ground - analogue

Ok, but I guess you have a few decoupling caps around the chips. My point is that the ground connection for all decoupling/bypass cap's should have it's own ground wire to the Star GND point, not mixed with the analog signal GND. I was amazed myself how much noise you pick up from those...

[nickarsow]

Dear Sergan,
Would like to send you the PROTEL file for opinion?
What kind of PROTEL files could you read?
Nick

[Segran]

Sure, I'd be glad if I could be of any help.

Bit I don't know what a PROTEL file is, I'm using Ultiboard (Multisim) myself. I also have Eagle.

Can you export to Gerber files, so I can use a Gerber file viewet?

[AndrewT]

Originally posted by Segran
[BI guess you have a few decoupling caps around the chips. My point is that the ground connection for all decoupling/bypass cap's should have it's own ground wire to the Star GND point, not mixed with the analog signal GND. I was amazed myself how much noise you pick up from those... [/B]

The Signal Ground must not be contaminated with any dirty (spiky) currents. All dirty currents must return to the Audio Ground (star grnd) on a separate connection from the clean currents returning through the Signal Ground.

[nickarsow]

Thank you Segran and Andrew,
Please find attached the gerbers for LME49380 module.
Write a few words of could you read the files.
Nick

[Segran]

No problem to read the files, but a schematic would be helpful. Can youu provide that as a .pdf file?

[nickarsow]

Dear Segran,
Please excuse me I can't send you the sch file now , because till monday I'm out of my work , but monday morning I'll send you the file.
Nick. Preliminary - the schematics is based on an original National's file and a 1/2 LM833 , 2 bypass electrolytic for the LME49830 and 2 for LM833. 2 outputs through resistors to the FETs and 3 connections to the external bias NPN. Nothing else - very simple , but the idea is that module could be used by anyone anywhere where needed.
Regards
Nick

[nickarsow]

Dear Segran,
Please find attached the schematics in *.bmp and *.dxf ( *.dvg ).
I'm sure you could read one of the files.
Nick

[Segran]

Hi Nick,

my advice (and AndrewT's) is still to use separate ground connections for power (decoupling caps and pin 3 onLME49830) and the analog signals and connect the both using separate wires all the way to the Star GND point.

This will minimize the noise level to a minimum. As it is done on the PCB now you will have a lot of 100Hz noise.

Connect the GND leads of R4, R6, R7, C7 and C10 to the Signal Ground, and all the remaining capacitors to Power Ground.

Good luck!