Single sided non inverting LM3886 PCB

[tla-Audio]

Hi everyone

Another LM3886 GC proyect.

The PCB is in PDF format, 1:1 scale and is oriented to the monoblock concept.
Provisions are made for dual rectifier snubberized power supply with dual size electrolitic filter capacitors footprint and polyester bypass capacitors.
Power on led acts as discharging path for the supply capacitors, when the amp is switched off.
Flexibility of the board allows 2 parallel input capacitors, ultrasonic input filter, poly capacitor between + & - pins, single bipolar or 2 opposite series Ci capacitors, switched or jumped mute circuit, Cf feedback capacitor, output Zobel network and series resistor or inductance (10 turns of 0.4mm enamelled copper wire, wound around the body of the 10 Ohm/ 2 W metalic film resistor).
The schematic will be posted soon.

M.Font

 

[PierreG]

Thanks. I like single sided boards. Easier to make at home.😉
Yes I would like to see the schematic and the components name on the silk screen.

 

[tla-Audio]

Hello PierreG

Here it's the silk screen, with the parts reference.

Next post will include the schematic.

M. Font

 

[tla-Audio]

These are the schematics.

You may notice strange layout, like caps in paralel, etc. This is due to the difficulty to obtain some parts at my country.

Hope my work would be useful to your projects.
Let me know if you have improvements to do.

This post has the schematic of the amplifier section.

M. Font

 

[tla-Audio]

This is the PSU schematic


M. Font

 

[zafira1981]

hi!!! this is exactly what I was looking for. schematic & pcb for a lm3886 project. thanks a lot!!!!


pd: somos vecinos, soy de Argentina 😉 tenés MSN?

 

[ArtiomR]

Thanks a lot for your PCB tla-Audio Recently I was in search for a good PCB for LM3886, and yours looks nice and with fat simmetrical ground 🙂

But I think, there is one mistake in your schematic and PCB - R2 resistor should be connected between Cin and R1, so that they form a high pass filter 😉

It would be very nice if you corrected this little issue and posted a new PCB file. Of course, I could do it for myself(in Paint ), but pdf is much better(scaling without squared edges)

Regards,
Artiom

 

[Pramod Kumar]

Hello ArtiomR,

Did you make the LM3886 PCB? Do you have a corrected version of the PCB layout posted by tla-Audio? If so, could you please upload it?. Thanks very much.


Pramod Kumar

 

[tubob]

tla

do you intend to sell the pcb ?...
or just want to share the work?..it is good

bob

 

[ArtiomR]

Somehow I didn't make an amp with Miguel's PCB Probably cause at that time I already made one with another PCB. The result didn't impress me 😱 Maybe I got fake LM3886s (one chip was not functional and after breaking it I saw a die glued slantwise!), or it was the PCB... anyway I lost interest in these chips. (I had better luck with TDA7294)

Anyway you may try Miguel's PCB - it looks nice 🙂

Artiom.

 

[beetel]

Capacitor CI shown near the word "GND" on PCB is not shown in schematic anywhere ? or may be I missed it.

regards

 

[AndrewT]

Hi,
the PSU in post 5 is wrong.
It shows a dual rectifier arrangement feeding the positive and negative halves of the PSU. This side os OK.

The transformer is shown as centre tapped. This is wrong.
The four connections on the PCB MUST be connected to dual secondaries.

 

[AndrewT]

Capacitor CI shown near the word "GND" on PCB is not shown in schematic anywhere ? or may be I missed it.

regards

Hi Beetel,
look again and you will see that (Cia+Cib) are parallel to Ci.

 

[beetel]

What is the value of Ci ?

thanks

 

[AndrewT]

What is the value of Ci ?

precise value hardly matters.
A low value film cap of about 1% of the electros is close enough.

Some say polypropylene is good here but they tend to be bulky and more expensive, but getting cheaper by the month.
Polyester is probably next best followed by Mylar (a lower quality version of ester film). PES are small and cheap.

 

[beetel]

Thanks for reply Andrew

A low value film cap of about 1% of the electros is close enough.

In the PCB file the Ci is shown as an electrolytic capacitor.

regards

 

[yangsmm]

Thanks all of you!

Thanks all of you. I needed the schemetics of lm3886. I'd like to make audio amps using lm3886.^^ Thanks a lot.

 

[AndrewT]

In the PCB file the Ci is shown as an electrolytic capacitor.

that must be an oversight.
He appears to have pulled up the wrong symbol.
There is little advantage in adding another polarised electro in parallel to the back to back polarised electros.
He surely intended to show a low ESR, low inductance, low distortion, bypass across the electros. The bypass will hopefully handle all the mid and high frequencies. The electros will bring up the bass.

 

[beetel]

tla-Audio has used two 2.7ohms /2w resistors in power supply and one 2.7 ohms/2w in amp circuit.

What type of resistors should be used here ?
Carbon film, wirewound, metal oxide, fusible or something else ......

thanks

 

[ollebolle]

I have just etched my first board using this design 🙂

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

I will etch the second one soon.