My tiny single sided LM3886 PCB layout. :)

[Russ White]

Please have a look at this and tell me what you think.

It is designed to utilize Carlos' Snubberized PS.

Cheers!

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[Russ White]

Well I guess there is nothing seriously wrong with it or someone would have piped up by now.

 

[tobias_svensk]

Helu Russ, do you have Eagle in your "Autostart"?

I'm sure it will work, and I'm also sure that you already have etch it?

On my board (wich is a 99% BrianGT copy, so thanks/sorry Brian ) I added snubberz before the big cap.
http://www.ettnet.se/~tobias/diy/lm3886/3886.png
Another (big)
http://www.ettnet.se/~tobias/diy/lm3886/lm3886opabuf.png

Keep spitting 'em out...

 

[Russ White]

Helu Russ, do you have Eagle in your "Autostart"?

Ah autostart now there an idea!

Nice work Tobias!

Thanks for the reassurance.

 

[asgorath]

could you please post the eagle files?

 

[Russ White]

could you please post the eagle files?

I will let this think loose into the wild only after I have tested it.

 

[Russ White]

Update

OK, I tweaked the layout a little and etched the boards. I will build the amp tonight. Here is the latest layout:

An externally hosted image should be here but it was not working when we last tested it.

 

[richie00boy]

Nice, but no zobel option?

 

[Russ White]

Nice, but no zobel option?

I have thought about adding that. But, my speakers already have zobels in them, so I figured why have two zobels in the output?

 

[richie00boy]

The zobel in the speakers is a different zobel to the one on the amp output.

 

[Russ White]

Yes, I know, but would they still not interact?

 

[Mr Evil]

The point of a Zobel network on the amp's output is to provide a low impedance termination for high frequencies, which increases stability. A Zobel in a speaker can't do that because it's seen through the resistance+inductance of the speaker cable.

Of course you might not need a Zobel, but it can't hurt to leave room for one, just in case.

 

[Russ White]

The point of a Zobel network on the amp's output is to provide a low impedance termination for high frequencies, which increases stability. A Zobel in a speaker can't do that because it's seen through the resistance+inductance of the speaker cable.

Of course you might not need a Zobel, but it can't hurt to leave room for one, just in case.

Yeah, I understand they have different roles, but I thought I read somewhere that they could interact. Still, I suppose putting places for the components is a good idea, and it can't hurt as you can omit them. I will do so in the next revision.

 

[mateo88]

Does pin 5 need to be connected to V+, or can you just choose between 1 and 5?

 

[BrianGT]

Re: Update

OK, I tweaked the layout a little and etched the boards. I will build the amp tonight. Here is the latest layout:

An externally hosted image should be here but it was not working when we last tested it.

The board looks good. It certainly is more tricky working with 1 layer.

Do you not need to tie pin 5 to V+? I haven't tried it without it, but I guess you could put a short circuit jumper on the chip package to tie these pins together to V+.

Best of luck with the amp,

--
Brian

 

[Russ White]

Hmmmmmm.... In the library I have pin 5 is not connected to V+! I will have to fix that.

Here we go.

An externally hosted image should be here but it was not working when we last tested it.

 

[BrianGT]

Looks better. Another suggestion is to make the NC pads on the chip smaller, so that you can maximize the power traces.

--
Brian

 

[Russ White]

How is this?

An externally hosted image should be here but it was not working when we last tested it.

 

[Russ White]

Now with zobel. I think is it.

An externally hosted image should be here but it was not working when we last tested it.

 

[Tekko]

Good job