Simplified LM3886 amp with PCB

[carlmart]

someone have an one side pcb for lm4870, lm3886 or lm3875?

The one above is an LM3886 one side pcb design.

Except for the LM4780, which is more tricky, you can adapt any double side pcb design for 3886 and 3875 and converti into single side. Parts are just a few.

Follow what Kostas changed since his first design to see how it's done.



Carlos

 

[cjd]

For the LM3875...

I have LM3886 layouts as well, just not handy.

C

 

[Peter Daniel]

someone have an one side pcb for lm4870, lm3886 or lm3875?

Check those: http://www.diyaudio.com/forums/sear...d=744366&sortby=lastpost&sortorder=descending

 

[samsagaz]

peter, ur link dont work, please just put the string that i need to search

cjd, thanks, ill try that.


carlmart, thanks for the tip.

 

[Peter Daniel]

http://www.diyaudio.com/forums/showthread.php?s=&threadid=32885

 

[samsagaz]

thanks peter

 

[samsagaz]

cjd

have u the schematic for that pcb?

 

[KostasTheGreat]

oK guys we are ready

here is the final pcb bottom layer

the dimension are 5x8cm exactly...


thank you carlos, thank you all!

 

[samsagaz]

kostas, u tested it?

 

[cjd]

cjd

have u the schematic for that pcb?

It's all in the datasheet... ROut is optional (useful if you try to parallel these).

C

 

[samsagaz]

thanks

 

[barroccio]

thanks for you all for the pcbs
now i'm lokking at a 3886 pcb like that CJD posted in post 22

thanks all group

 

[carlmart]

thanks for you all for the pcbs
now i'm lokking at a 3886 pcb like that CJD posted in post 22

The post 22 pcb is for 3875. Try Kostas design for 3886.


Carlos

 

[demogorgon]

nice layout, but some of the part values are "gone".

would you mind writing the complete part list?

regards
marius

 

[KostasTheGreat]

Parts List:

Resistors:
2 x 220K 1% film resistor
1 x 56K 1% film resistor
1 x 10K
1 x 27K 1% film resistor


Caps:

1 x 47uF
3 x 100nF
1 x 100uF electrolytic
2 x 1000uF 50V electrolytic

1 x LM3886T of course


you can take a look on the schematic
the two bypass caps of the 1000uf will go as near as possible either under the pcb or in the left space beside caps.

search the complete post for the last pcb revision6

 

[demogorgon]

thanks for the help Kostas!

this was indeede what i needed to start building the amp.

 

[demogorgon]

Indeede, now two pcb's are lying in my pocket, ready for hole drilling and soldering.

i'l come back to you with some results in time.

 

[demogorgon]

uhh.. why the 220kohms resistor from the input to the -V rail?

 

[carlmart]

uhh.. why the 220kohms resistor from the input to the -V rail?

Look again. 220K resistor is between - input and output. There's another 220K from + input to ground. In fact I'd use a smaller resistor (10K to 22k) there and cut the cap.


Carlos

 

[demogorgon]

I think you should look again at his pcb rev.6 as it at least to me is quite clear that he put the 220k resistor between the input and the -V rail.
i didn't think about this before actually realizing that the membrane on my speakers were trying to leave the box! it sets the output at 25V you know...

i put the resistor at the output instead, and it works now, but it diden't before.