digital attenuator

[mtoc]

hi kg, any upadtes on this?

[kevin gilmore]

Kerry was going to publish code soon

Edited March 23, 2016 by kevin gilmore

[mtoc]

will we get better result when using vishay resistors rated at .01% (some of them are 5 ppm, seems be the king)?

[Pars]

You'll get a tighter match to the ideal resistance curve of the attenuator. Whether it will be audible or not, doubtful. 0.1% should be good enough.

Some might say using the naked Vishay s102/z102 would be the best (and most expensive), but I don't think these are available in surface mount.

[luvdunhill]

It's more important to use E96 series resistors than the tolerance levels.

[mtoc]

On 2016/5/16 at 9:59 AM, luvdunhill said:

It's more important to use E96 series resistors than the tolerance levels.

Wow, why E96 is the key?

[UFN]

Closest to the ideal values probably?

 

//UFN

[luvdunhill]

Exactly. I suppose you could parallel each position and calculate closest parallel equivalent, but yes - this is more important than 0.01% because in fact a 1% might randomly get you closer to then ideal value.

[Kerry]

I've got my controller boards working pretty well now with the digital attenuators.  I like the larger one because it has a really nice feel as you turn the volume knob (...yes I see it ).

I went and added a USB input to the board itself, though this is really overkill - which is why I did it.

 

Here I'm updated with the TX / RX LEDs blinking away.

 

EDIT: I've got to do one more round of cleaning...

Edited March 19, 2017 by Kerry

[kevin gilmore]

Outstanding

 

[JoaMat]

Great thing the usb port - makes life easier.

[Kerry]

Here's the code.  Just rename the PDF to Zip and expand it into a folder under your .../Documents/Arduino directory.

The code works well now, though there are a few things I'd like to keep working on.  It will drive one of the I2C 1" OLED displays.  I typically comment this out at line 101 in the main program (EDIT since I don't use the display in the amp)...

  //  If not using display just don't create it
  activeOLED = new OLED (128, 64,SSD1306);                                                        // I2C Display
  //activeOLED = new OLED (128, 64,SH1106, OLED_MOSI, OLED_CLK, OLED_DC, OLED_RESET, OLED_CS);      // 1.3" SPI Display
 

I'm happy to keep working on it.  I can post the Gerber files as well at some point.

 

VolumeController.pdf        ->  rename to VolumeController.zip

 

EDIT:  I just wanted to add a note that this will work on an Arduino UNO or Pro Mini.  Pretty much anything with an Atmel 328P.  Could probably support other chips as well.

EDIT 2: This code will run the older and larger I2C boards (requires a slight code change) as well as version .4 and .5 of the current SPI boards.

Edited March 19, 2017 by Kerry

[ti5002000]

Hi guys 

Does someone have boards that don't need and can sell it to me? 

They can be only the pcb and also can be already populated. 

Thanks for the help 

[swt61]

On 3/19/2017 at 4:23 PM, Kerry said:

I've got my controller boards working pretty well now with the digital attenuators.  I like the larger one because it has a really nice feel as you turn the volume knob (...yes I see it ).

I went and added a USB input to the board itself, though this is really overkill - which is why I did it.

 

Here I'm updated with the TX / RX LEDs blinking away.

 

EDIT: I've got to do one more round of cleaning...

That is just all kinds of cool!

[Horio]

7 hours ago, ti5002000 said:

Hi guys 

Does someone have boards that don't need and can sell it to me? 

They can be only the pcb and also can be already populated. 

Thanks for the help 

I think I have a couple boards I could sell you.  Send me a PM.

[cspirou]

On 8/14/2017 at 7:11 AM, ti5002000 said:

Hi guys 

Does someone have boards that don't need and can sell it to me? 

They can be only the pcb and also can be already populated. 

Thanks for the help 

You can check with @sorenb

[ti5002000]

Thanks @cspirou i already talked with other forum member for that.

Thanks for your help anyway

[tomislavkufrin]

On 7/23/2015 at 10:59 PM, kevin gilmore said:

for the V2 attenuator, there was one missing wire, will fix soon.

 

 

fixed

 

http://gilmore.chem.northwestern.edu/boards/attenuatorsmtv2.zip

 

http://gilmore.chem.northwestern.edu/attenuatorsmtv2.pdf

i have a question. i have tried to get quote for this board, and when i have uploaded the gerber file, system detected 3 layers. i can choose between 2, 4, 6. if i were to use 2, what happens if this inner layer is discarded? or in case of 4 layer, i suppose this inner layer is then duplicated and then there are two 2-layer boards pressed together with same inner layer?

thank you

[kevin gilmore]

its a 2 layer board. not sure why it is being detected as 3 layers

[Pars]

There is one layer labeled Inner 1 in the gerber files.

attenuatorsmtv42flipground7 - CADCAM READ-ME.doc

[kevin gilmore]

that one is indeed 3 layers, extra complete ground layer in the middle. forgot about that one.

[sbelyo]

Did anyone ever put this together with the selector boards that were run?  I was looking at AMB's setup for volume and selecting sources but I seem to remember somebody saying that his attenuator won't work with the amps here.  It would be cool to put this together with the SE/BAL to BAL/SE board

[Aive]

On 6/6/2019 at 4:09 AM, sbelyo said:

Did anyone ever put this together with the selector boards that were run?  I was looking at AMB's setup for volume and selecting sources but I seem to remember somebody saying that his attenuator won't work with the amps here.  It would be cool to put this together with the SE/BAL to BAL/SE board

I got a set of two boards I’m planning to build soon - too many projects but this has come back on the radar

[randytsuch]

Anyone still have boards?

Decided I'd like to give this a try if I can get my hands on the boards.

Randy

[Max]

On 6/14/2019 at 9:49 PM, randytsuch said:

Decided I'd like to give this a try if I can get my hands on the boards.

If you can't find spare boards then you could just add a 4th layer (like just duplicate the middle layer) then you could get new boards made quickly and cheaply at a place like https://oshpark.com

Otherwise 3 layer is less commonly available and you might have to go to a more expensive PCB manufacturer.