Hello everybody,
I'm using a lilypad powered the liPower. When I connect to the serial port the microDrive SD module (http://www.sparkfun.com/commerce/product_info.php?products_id=8567) I hear a strange noise.
The noise seems to come from the liPower's inductor. The microModule needs 23 mA to operate and lilypad ports can provide up to 40 mA. So, I think that the noise is not due to excessive current.
Some idea?? Thanks!
lilypad ports can provide up to 40 mA.
That's each output port pin add them up. But that is only if you connect them to something that takes 40mA.
A switched mode inductor will often ring like this under different loads so it is not a function of over current but just different current. Check for over current but don't worry too much about it.
One solution is to do what I have done and go to a lot of live gigs and get old then your top end hearing response is shot. 
Mind you it might just be that the tinnitus is drowning it out. I had a similar complaint from some software engineers on my current project and I had to resort to bring in my bat detector to here the noise.
eheheheh....thankyou very much!