V2.0 -> Adding Audio

After printing the earlier version. I have been trying to make a bigger moon lamp, which can also double up as an audio system, for tuning in your FM radio or playing audio from your phone.

While getting a FM tuner is in the works, meanwhile I started with developing speaker system. Basic requirements being , I would want a stereo setup, with audio levels sufficient to fill a room, all while the entire setup is being powered over USB 2.0 cable ( 5V, 250mA max current)

Initially I wanted the module to be as compact as possible , so bought a PAM8403 audio amplifier module which offers 3W+3W audio output. Accorodingly I bought small laptop speakers which were 2W each. But as luck would have it PAM8403 did not offer good audio quality and speakers sounded a little too harsh, and well a little less fulfilling.

Readers might question, that the speaker power (2W*2) is more than what the power supply can provide (5*250mA = 1.25W). The speaker power is listed as rms power, so average power requirements are often less than that. It is important to note that the transient power requirements are met by the decoupling caps, rather than the power supply. The decoupling caps act as temporary power supply to meet the instantaneous current demands. As long as there is sufficient decoupling in the power supply network, the power supply itself can be designed for average power requirements.

Anyways unhappy with PAM8403 performance , I switched for bigger 15W speakers, ( a conventional 3 inch dia round speaker), and TPA3110 audio amplifier. The audio amplifier needs 8-24 V input, whereas USB only gives 5V supply. For some unknown reason I am fixated on keeping power supply via USB. To fix this problem, I use a boost converter (MT3608) module. I tune the boost circuit to give a 12V input.