[saab]

I bought Guzzler's USB DAC from doobooloo a bit ago. I am wondering what the best method is of powering these units. Right now it has a battery compartment on the front of it (seen in my avatar) that holds four AA's. I would like something a bit more permanent than batteries. I understand it wiuod be a bit difficult to try and switch it to USB power, and might introduce some noise.

Thanks for any advice.
-John

 

[dsavitsk]

USB power actually works remarkably well. The noise is quite low.

There are tons of wall powered solutions as well. Keep in mind that they will likely introduce noise of their own, so quality matters in choosing components.

-d

 

[saab]

How then would I go about changing from battery power to USB power. What would I have to change on the board?

Thanks
-John

 

[dsavitsk]

Assuming that the board is fully populated (and you'll need to post a picture so someone can see) you simply connect one pad of R7 to batt (the + terminal, not the ground.) The Rev A boards were supplied with an inductor to do the connecting as it is supposed to reduce noise a bit. Here is the project page with some more details http://www.mellowparenting.demon.co....er/usbdac.html

 

[saab]

Thanks, I will have to post a picture monday. It is fully populated I am assuming, because I have been using it for a while now.

I will read throught the page you posted and see what I can't learn.

Thanks again
-John

 

[dsavitsk]

There are a few parts that are only there for reducing USB noise, so it is possible he left them off. Out of curiosity, is there something wrong with the battery supply?

 

[saab]

No, nothing wrong, I just like the idea of something a bit more permanent that batteries.

 

[DaKi][er]

How about just an lm317 regulator set to about 5.5-6v and plug it in to the >5V hole after the step-up switcher and before the onboard 5v regulator?

There are a few ways to achieve this but their all the same basics in the end just depends on if you want to go internal or external (wallwart) transformer, diy your regulator board on protoboard or build tangent's tread regulator, etc.

But something along these lines will be about as good as you can get for the dac

 

[saab]

Sorry to bring this back up, but this is the DAC that I have. I have not had a chance to take pictures myself, so there is probably not a clear enough shot to tell, but I would like to run off USB power.

Thanks for the advice so far. I wish I knew more about DIY, and I am trying to learn. Please remember that I am a novice.

Thanks again
-John

 

[dsavitsk]

If you look at the board, on the end with the USB jack, there are two little pins encased in white plastic sticking up -- this is where the battery connects. The one of these pins that is furthest from the USB jack needs to connect to one of the litte metal circles (which surround holes) next to where it says R7 on the board. Which one of these you use does not really matter, but the one right next to the USB jack is the one I always use. The board generally uses an inductor to make this conection. I don't think it really matters, but maybe someone else can chime in if they think it does.

This is not a terribly difficult thing to do, but it is fairly delicate, and if you don't have a proper soldering iron, etc, it will likely be a big pain.

Anyhow, I have an extra one of those batter connectors, and it would be pretty easy to use it to make a removable connector from R7 to Batt such that you could choose whether you wanted to power by USB or by battery. PM me if you want to discuss the prospect.

-d

 

[DaKi][er]

sort of repeating what dsavitsk said, but i even had a bit of a headache understanding it (no offence) but to power off straight usb, you connect from the R7 resistor position to the V+ pin where the battery connects and have an inductor inbetween

the value of the inductor doesnt matter too much, i had a heap of 390uH lying around so thats what i used