Integrated AMP with PGA 2311 preamp

[kpero]

Hello everyone. I am trying to make one amplifier with integrated PGA 2311 as digital pot and preamp. I know it's only 5 V chip but I got it as a sample and it's very annoying to look at that IC in my electronic box at home. So, I look on web and find few project which have that chip as a base unit.
For input I will use some relay which will be controlled with PIC. PIC will also drive PGA and LCD display. I think I will put some IR control also, but for now I will stay without IR unit.
Analog part will be supplied trough some shunt regulators and digital trough 7505 regulator.
I think that I will put some input buffer for PGA, but I don't have any idea which chip to put in there.
OK, that's all for now.

I draw some schematic and PCB so have a look and try to help me to improve that layout and schematic.

My basic question is, how to connect ground from PGA to RCA input connector on relay board. I draw some polygon from AGND but I don't know is it correct.

Here is the schematic

and input circuit



and here is the board 100*145 mm

[jaycee]

I think you have done quite well here. Looks good to me

One part I could recommend to you is TI's "PowerLogic" TPIC6C595. This is basically an 8-bit shift register with common-drain MOSFETs on the outputs - ideal for switching relays with! TI will even give you a few samples

[kpero]

Hi all,

I have finally find time and started to work on this amp. I build AMPs board, and now I am working on the design of other boards, like protection, and PSU for AMP.
Here is my design of protection board.


and PCB


and this is the PSU for AMP

and the PCB


I will need some help with routing the ground point. The transformer has two secondary windings, and the two rectifier. What is your you suggestion? Should I connect this middle ground tracks of two of the large caps together or leave it like this. Of course, I will use larger dimension for the tracks on PCB. This is just the idea.

Here are some picture of AMP board.
http://fly.srk.fer.hr/~kpero/images/...ojacalo/slike/

Thanks

[Stream]

Hello, can You post schematic and BOM for your amp?

[geekysuavo]

kpero,

looks like a working design... how does it sound?

~ brad.

[kpero]

Hello,

No, it's not yet finished. I have problem with PIC programming. I am not some computer freak so I am trying to write some working code. I made some changes to board for input switch and preamp because in first design I made some error in power supply. I have connect PGA to +12V digital supply, but it's working only with +5V.

Amplifier is finished, I have made some proto connection and it's working all right. Here are some pic. Sound is very good. I am driving my DIY transmision line speaker with it, and the bas is very clear, but I think that HF are mybe slower then I expected. But, first I must make some box to put it in it, and connect it to my DIY preamp. After that, I can tell more .



amplifier boards with cooler


PSU with soft start and ground loop circuit with two diodes and resistor



Transformer made in local workshop