help with my volume control, input selector, and other questions

[jufreese]

Im trying to build a preamp that will do a few things.

First, the volume, treble, and bass controls.
I have an LM1036 that was a free sample from National and I have the circuit for it here:
http://www.national.com/ds/LM/LM1036.pdf

In the circuit they use pots for controlling volume, bass, and treble, which is fine, but what if i wanted to use push buttons.

My next question is how can I display a volume, treble, or bass on a seven segment display?

I know how to use pld's and other micros so that wont be a problem.

My last question is how to make the audio input selector circuit.
I have seen a circuit that uses relays and a rotary switch, but i would rather have individual push buttons for each input.

If anyone can give me any clues that would be great, thanks.

[analog_sa]

Originally posted by jufreese

I know how to use pld's and other micros so that wont be a problem.

Isn't this a bit of a contradiction with the rest of your post?

[Moose]

I'm working on something similar but don't have any schematics ready yet, as I'm still researching parts. I plan on building an 8 channel preamp/source selector around an arduino controller. I decided digital would be much easier to get all the functionality I wanted and still have clean controls and displays.

As it stands at this point, inputs will be:
-2 rotary encoders (one for volume, one for source selection)
-pushbuttons for menu traversal/selection

Display will be an LCD like this one:

20x4 LCD Display

Volume control will be through PGA2311's, source selection will be with some form of relay drivers (maybe TPL9201?) and TQ2 relays. I also plan on having electronic high pass crossovers (100 Hz) that can be enabled or bypassed. I'm not sure about tone controls yet, as I have yet to find something suitable.

[Moose]

Originally posted by jufreese

My last question is how to make the audio input selector circuit.
I have seen a circuit that uses relays and a rotary switch, but i would rather have individual push buttons for each input.

You should be able to do this with some simple logic and latching relays. Say you have inputs A, B, C, and D. When the pushbutton A is triggered close relay A, and open all other relays (B,C,D) When pushbutton B is triggered close B, open A, C, D, etc...

[jufreese]

Originally posted by analog_sa



Isn't this a bit of a contradiction with the rest of your post?

I know how to use them....but not extremely well....basically don't know how to make analog into digital

[analog_sa]

Analog into digital? You only need a simple push button interface to a micro, or a rotary encoder. As for replacing the LM1036 pots with electronic pots, it's certainly possible. You can use a number of available electronic pots such as DS1802 which has a simple push-button interface or something like a DS1666 which requires a micro. The 1666 is probably more suitable as you would want to display the position.

Can you not find a digitally controlled volume/tone control? Surely many such ICs must exist.