CD4067 Volume control

[audioPT]

Hi!

I'm wondering if anyone can help me with resistor values for this volume attenuator.

I'll command it with 4 bit to have 16 levels.

So, having the fisrt 10 levels with small difference, say 1 dB and the others from 3 dB, how can I figure out the resistors values?
Any formula?? Or I must use the ohm's law?

Thanks in advance


Pedro Martins

[audioPT]

The parcial schematic

[till]

as a suggestion, take a look at the d1-svr-man.pdf at passlabs.

i can´t find any english pages at your www.

[Bill Fitzpatrick]

I think this is what you are looking for.

http://www.quadesl.com/attenuator.html

[audioPT]

Originally posted by till
as a suggestion, take a look at the d1-svr-man.pdf at passlabs.

i can´t find any english pages at your www.

I'm updating the layout, sorry...
When I'm finished, I'll send a mail to you

[audioPT]

Here is some values:

Please comment. This gives a 22k load to the preamp

[jleaman]

This Looks Interesting

[audioPT]

Guys,

I'm going to use the attenuator with 6 4067 to control a 5.1 preamp using one control unit.

This is only because I've got a log of PGA2310 and some PIC's but I still can't learn how to program them

Do you think it is a good second solution?

[till]

This is only because I've got a log of PGA2310 and some PIC's but I still can't learn how to program them

If you don´t need them - send them to me.

You can simply use my code to controll the PGAs. At the moment i make a version for 16F877, for 16F628 you find here: http://home.tu-clausthal.de/~tpa/PGA/03.asm

[sajti]

I made some volume controll with 4067, even 256steps, with two units
It works well, but for low distortion use very high input impedance buffer for it. I used two opamps (one between the two 4067) with gain of 1, non inverting, with 330-470kohm resistor between the +input and the gnd. Some muting is also necessary to avoid switch noises....

sajti