8bit music player

by seer on Jun.29, 2010, under My gadgets

When I saw the 1-Bit Symphony, it gave me a new view to the case and arrangement of the circuit. But in technological perspective, the 8 pin IC can do more than mixing the triangle and square waves. I mixed it with chan’s “Simple SD Audio Player”.

The circuit can be laid out on a small piece of single side board. The micro controller read the value of the music from the PCM files in the micro SD card. And the value is converted to the duty cycle of the fast PWM outputs. Although this is a digital signal, but the inductor in the earphones and the capacitors act as a 2 order low pass filter. Then we are able to hear the songs played by the chip. This method is significantly efficient because no power is wasted on resistors. If the potentiometer is set to zero, the sound from the earphones is loud enough to be heard in a far distance.

The board is powered by a 1700mah lithium battery which can work for 85 hours at 20ma consumption. The 20Kohm potentiometer is used to control the volume to a comfortable level. All parts are pasted in a floppy disk case which is much smaller than the 12cm CD case. This make the player suitable to every day’s carry. Also the quality of the playback is not inferior to a commercial mp3 player.

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