I dont know if this is the right place to ask this but I have been using the waveshield based circuit on some devices to play sound clips from a SD card.
One unit failed, and while faultfinding I see that from the circuit diagram that I sort of copied from http://www.ladyada.net/images/wavshield/v11/wave11schem.png that the 74ls125 is used as a buffer between the 5v data lines from the micro, to the 3v3 SD card.
What I didn’t notice was that the 74125 is powered from 3v3 ( the data sheet says min Vcc as 4v75 ? )
The inputs to the chip are 5v but the outputs are less than 2 volts.
I don’t know if this is part of the trouble, I havn’t got it working yet, but has anyone had problems with this ?