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Audio Power Distribution Amplifier

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Nigel Goodwin said:
No decoupling capacitors on the potential dividers again though?. You could also feed all the opamp inputs from a single potential divider.

Thanks for your reply Nigel I was wondering about driving them from one potential divider but was worried about interferance between the mono and stereo or just the left and right.

Decoupling capacitors are missing from the diagram "forgot about them and was lazey whilst drawing me bad"...

Im going to re-think me design and make it more efficient now..

Many thanks for your reply and reminding me about the simple things that I forget all the time...
 
clipo said:
Thanks for your reply Nigel I was wondering about driving them from one potential divider but was worried about interferance between the mono and stereo or just the left and right.

That's one reason the capacitor should be there!.
 
Nigel Goodwin said:
That's one reason the capacitor should be there!.

Hi Nigel would this be a trouble free design ive included the decoupling capacitor and Im becomming to understand the purpose of it.

I will of course decouple the powersupply to the opamp.
 

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clipo said:
Hi Nigel would this be a trouble free design ive included the decoupling capacitor and Im becomming to understand the purpose of it.

Yes, that's fine - the two resistors essentially generate the centre point of a spilt supply - it's standard opamp practice.

BTW, I notice your circuit was posted as a JPG file, if you use GIF or PNG it will not only be far better quality, but will be considerably smaller as well!. JPGF is designed for photos and such, and should only be used for that!.
 
Nigel Goodwin said:
Yes, that's fine - the two resistors essentially generate the centre point of a spilt supply - it's standard opamp practice.

BTW, I notice your circuit was posted as a JPG file, if you use GIF or PNG it will not only be far better quality, but will be considerably smaller as well!. JPGF is designed for photos and such, and should only be used for that!.

Many thanks once again for your help I'll carry on building the amp now and will incorporate that design in..

And thankyou for your tip about posting I will post any diagrams as GIF in future.
 
Hi all the amplifier is built and is for the most part working very well, but since im not posting the final pictures and drawings there is a problem that I could do with a little bit of advice on...

So the amp is working perfect and when powered up with nothing attached there is a little noise but nothing to bother about, the problem starts when I plug the input lead into my PC's sound card I start getting iterferance from for the most part the hard drive and the rest of the PC Im guessing this must be comming down the input ground line since its fine before I plugged it in.

I'm also guessing Im going to have to decouple this input but im not sure if that is the right solution or if it is what sort of decoupling cap to use.

Any ideas or sugestions people...

Update:
just tried a different power supply for the amp and it seems to be working well enough with a little noise but less than with it connected to the host PC power supply so it must be a ground decoupling problem for the main ground maybe will try and few different things.
 
Last edited:
Update:

Ive figured out where my noise is comming from and worked it down to circulating currents in the ground since im using the PCs power supply and the PCs sound card the ground in the signal wire and my main ground are coming together to cause me a little trouble.

I'm still learning about these problems and would welcome any comments or advice Im also now concidering an external power supply since it works perfectly with one.

Here too are some photos of the prototype for any one to poke fun at :).

I'm going to build my next version on a custom PCB that I will make and so would like any advice or guidance on where to start to learn about PCB making and all the is required, I will of course be googling this topic when I start the next phase.
 

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Good work, thereare plenty of places to learn about making PCBs. Try searching Google or even this site.
 
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