XO-1.5 audio input DC mode

[forster at ozonline.com.au]

This sounds like the problem with TurtleArt
The bias is present in voltage mode.

The version for sensors on the xo1.5 is
http://bugs.sugarlabs.org/attachment/ticket/2506/TurtleArt-104.xo

The bias is not leakage and capacitance, 15k ohms at the socket halves the bias voltage at the socket.

It is not necessarily the same issue though, could be in the turtleart code, amixer code or hardware.

Tony

> On Wed, Nov 24, 2010 at 6:52 AM, Sascha Silbe
> <sascha-ml-reply-to-2010-3 at silbe.org> wrote:
> > 2. The voltage I see with bias off is probably generated internally by
> > � the codec chip. [...]
> > � Unless someone finds a magic way to disable this from the digital
> > � side of the chip (which I doubt), we'll have to cope with it. This
> > � means that we need an external buffer circuit in order to prevent the
> > � XO-1.5 from feeding voltage back into the measured circuit.
> 
> What is the impedance of your input?  What's the capacitance?
> 
> I can see getting some leakage current into a high-impedance
> high-capacitance circuit, but for most purposes this shouldn't really
> be a problem.
>  --scott
> 
> -- 
> � � � � � � � � � � � �� ( http://cscott.net/ )
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