We need a simple (existing) solution to take the USB audio out from smartphones' USB port, and then DAC, amplify, and drive an external speaker.
We only need to work with the standard USB audio out. See image below.
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In summary, we want the circuit from the USB audio output port of the phone all the way to the external speaker.
We only look for people who have the existing solution already.
Thanks for your interest.
This is a hardware design engineering task. We only look for people who have the existing solution already.
Beside the standard USB DAC, we also need:
1. A USB (audio out) DAC (sound card) with headphone out for the latest apple iPod. The audio stream source (out) of ipod needs to be taken from USB interface (digital audio signal), not the traditional headphone jack of ipod.
2. USB DAC for latest Android phone and take the audio stream from the USB/charging port and convert to headphone jack signal (analog stereo audio).
See the difference here:
You may send quote for any of these projects.