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sl1mshadyx 19th November 2006 09:21 PM

First LM3886TF-based build
hi, i need a new amp to drive 2 speakers that i have, and searching around for amps, i found that chipamps are the way to go, i know about basic electronics, but this is my first "freelance" project aside from school projects, where the teachers already gave me all the specs.

now, the amp:

i found this circuit, but i think it lacks of input and output decoupling capacitors (what values can i use?), and looking at other circuit that i found on a local electronics web, i think i'll add a 100f cap between pin 8 and gnd, to act as power on delay.

im planning to add a 10k pot to the input for volume control too.


i found an schematic here with some kind of "ground isolation", to isolate mains ground from audio ground

i'll apreciate any comments/suggestions/upgrades to the circuit, and when i get your approval, i'll design the pcb and post it here :)

thanks for reading this, and sorry if i had any spelling/grammar errors, english is not my native language :smash:

CarlosT 20th November 2006 05:40 AM

Another Porteno...welcome :D

Yeah...I like the decoupling ground circuit.

Where's the rest of your amp? :D

Spasticteapot 20th November 2006 06:22 AM

Most people don't add anything to the preexisting circuit for a reason:

1. Simplicity is easy and cheap, and
2. Nobody seems to need it.

Nordic 20th November 2006 07:11 AM

I made PCBs of decoupling networks like those nothing funny to it, it just sits between the amp and the case, which in turn is connected to mains earth.

Output cap is not a needed unless you have a large DC output.
Input cap is not needed unless you have DC on the input... like maybe a preamp without output caps...

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