LM3886 based amplifier

russo

Member
2008-01-21 2:40 am
Coimbra
Hello to all of you, as I said in my presentation I'm a newbie in matter of DIY amplifiers and I want to start building a lm3886 based amplifier and respective power supply, but after some searching in the forum I haven't find a lot about this chip amp.
So what I am asking to you is if someone could help me with some schematics to build the amplifier an the PSU and/or show me some post's with projects based in this chip.
 
russo said:
Hello to all of you, as I said in my presentation I'm a newbie in matter of DIY amplifiers and I want to start building a lm3886 based amplifier and respective power supply, but after some searching in the forum I haven't find a lot about this chip amp.
So what I am asking to you is if someone could help me with some schematics to build the amplifier an the PSU and/or show me some post's with projects based in this chip.

Welcome, russo!

There is probably at least a solid YEAR'S-worth of reading about the LM3886 on this site.

I used the 'Search' button to search for 'LM3886 schematic', searching only in the Chipamps forum, and found 229 threads:

http://www.diyaudio.com/forums/sear...63585991&sortby=lastpost&sortorder=descending

Maybe first, you could look at the threads with the most replies. Those probably contain the more-'famous' of the schematics.

ALSO, make sure that you have downloaded both the LM3886 datasheet and Application Note AN-1192, from National Semiconductor's website, at http://www.national.com . Both contain schematics for, and necessary information about, LM3886-based power amplifiers.

Have fun!
 

russo

Member
2008-01-21 2:40 am
Coimbra
gootee, I have made a similar research, but all the projects I have seen are way to complicated to me and the post's in that projects have a lot of knowledge but it's to much for me because it is a level beyond me!
but thank for the fast response.

tangmonster, this look's like it is a "simple" build, I will read that manual and the datasheet of the LM2886 and then I will ask here my doubts.
Thank you.
 

russo

Member
2008-01-21 2:40 am
Coimbra
Well i have already some reading in the topics that both you showed me, and i'm thinking to make the CarlosFM LM3886 based amplifier and the respective PSU, and here are the schematics:

[IMGDEAD]http://img179.imageshack.us/img179/9762/cfmchipampunregulatedpssu3.png[/IMGDEAD]

[IMGDEAD]http://img179.imageshack.us/img179/2061/cfmnilm3886v4ag5.png[/IMGDEAD]

And I have already a doubt, can I make all this circuits in a point to point board?
Should I use coper wire to connect the components under the board or just use "solder wires"
 
If By solder wires you mean solder , i think you will find that it is WAY too soft. Point to point is very possible.

You might want to go the lm3875 route since it has less used pins.

For the powersupply , start simple and add afterwards.

Vero boards I found makes things a lot easier for me.
And it is cheap and easy to use.
 

russo

Member
2008-01-21 2:40 am
Coimbra
About the LM3865 I had already read a lot about it but I cant get it in Portugal, and the samples from National Electronics would cost me mora than 40€ in transportation!

What I meant with solder wires was to make things like this:
[IMGDEAD]http://img401.imageshack.us/img401/8084/dsc00685vq2.jpg[/IMGDEAD]

And one more thing, in CarlosFM amplifier the LM doesn't have any numbers, how can I figure what is what?
 
I second the Chipamp.com suggestion, that way you will get a working amp after your labours.

Build one of those and spend the rest of the time listening. Theres nothing more frustrating than putting time into something then it not working and you dont know why.

If you use a tried and tested pcb it eliminates many possible problems, and you can build the CarlosFM version once you have found the answers to your questions and see how the two compare.

I'm using the CarlosFM "Uno" preamp with a Chipamp.com Lm3875 and I think it sounds great.
JB
 

maurycy

Member
2005-12-24 4:34 am
NJ
If you order kit from chipamp, the stereo one is $70 and international shipping is $14. That's not that expensive. I send all kinds of different packages to Poland (from US) and $14 sounds reasonable.

I myself built the LM3875 amp based on chipamp kit (they were selling LM3875 about 2 years ago). I am noob like you so kit was definitely way to go for me.
 
russo said:
I have already read the LM3886 datasheet, but my problem is to know what pin is what in the CarlosFM schematic.:(

Hi russo,

I don't understand how this can be a problem.

In Carlos' schematic, all of the pins except one are drawn just like a standard opamp schematic. So the 'non-standard' one is surely the LM3886's Mute pin.

The "schematic"-corresponding pin numbers are shown in Figure 1, "Typical Audio Amplifier Application Circuit", on Page 1 of the LM3886 datasheet. And the corresponding physical IC package pin numbers and locations are shown on page 2 of the LM3886 datasheet.

So, from the datasheet: the LM3886's + and - inputs are always pins 10 and 9. The power supply V+ always goes to pins 5 and 1. The power supply V- always goes to pin 4. The output is pin 3. Mute is pin 8. And pin 7 is Ground.

The only one I can see that might not be obvious, at first, on Carlos' schematic is the one with RM connected to it. That is the Mute pin, i.e. pin 8. Carlos used the same name for the resistor as is used in the component list on page 8 of the LM3886 datasheet.
 

maurycy

Member
2005-12-24 4:34 am
NJ
russo,

Send e-mail to BrianGT from chipamp.com and I am sure he will work with you to send the package insured. I do not think insurance on $70 value would increase the shipping cost that much.

I just got a modchip for my Xbox from Romania sent via regular mail. It arrived in little over a week with no problems.