Controlling volume of an amplifier..

[abidr]

Here is my approach to control volume of any amplifier, i have used DS1802 a digital pot from Dallas Semi with buttons control. No need for a microcontroller. These are schematics and layouts of the circuit, it uses five buttons mute, up, down, right, left.
I have three boards of the same. Using one of them with amy amp , a gainclone based on OPA549 and in realtime it really rocks.

[abidr]

Here is another approach, this is a pre amp and volume controller which uses PGA2310, an IR, switch to change input (a 4 input selectors) , PIC 16F876A, 16x2 LCD and rotary encoder.
Pre is complete, I have made the software in PIC Basic Pro, these days I am testing the code, once its complete I ll try to post it at the board as a help for others.

[Ioannis]

Hi abidr,

nice project with the PGA device.

As I am lacking inputs for the many audio sources I have now (Mini disks, CD players, tuners, Tape cassete recorders, Phono, Pc, Mac etc) I need a pre-amplifier with many inpusts but also have the ability to send a selected input to a recording device independently. I need to have at least 3 outputs for recording while listenting to a 4th input. A little complicated and many relays but I think I will manage it. It will complement your design nicely!

Ioannis

[falingtrea]

Heh, for controlling volume, I would figure out a way to drive the volume knob with a servo. Less issues with audio quality that way.

[mister_e]

Nah.. no need for servo... there's some motorized pot and faders already available on the market. Penny & Giles are the really first that spring to mind (for faders). Almost sure that ALPS do some as well.

[abidr]

Ioannis:
I think what you have mentioned is not very difficult to achieve, but for that you ll need a bigger PIC like 16F877A and probably two ULN chips. I intend to make an input selector with a simpler PIC like 16F84A, but insted of relays I would like to use something like MPC507A or if I want to complicate circuitary I ll use something like SSM2404.
Here are a couple of PICs of the populated pre amp its a very small size PCB like 4.5x4.5 Inches.

[Ioannis]

Both chips look nice although MPC507A does not refer any distortion in audio range.

But I think the relay solution gives much better results in whole (crosstalk, distortion etc).

Ioannis

[smartufo]

Ioannis:
I think what you have mentioned is not very difficult to achieve, but for that you ll need a bigger PIC like 16F877A and probably two ULN chips. I intend to make an input selector with a simpler PIC like 16F84A, but insted of relays I would like to use something like MPC507A or if I want to complicate circuitary I ll use something like SSM2404.
Here are a couple of PICs of the populated pre amp its a very small size PCB like 4.5x4.5 Inches.

Very good design Abidr.Please tell me what the IR code of your remote control (Sony,Philips..) and which compiler for your project.Thanks.