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A mini PC Sound Card

This circuit is pre-eminently suitable for PCs and laptops that are not equipped with a built-in sound card but do have a USB interface. However, the ‘mini PC sound card’ can also be useful for other applications and various experiments.The introduction above provides a nearly complete character outline for the circuit under consideration. In brief, it is a 16-bit stereo version of a digital to analogue converter with USB interface. The converter may be used for a range of audio applications. But the first thing that comes to mind is an external sound card for PCs and laptops without such a card, or as an expansion card in the event a second one is desired.The circuit is conspicuously compact and simple by design, because it consists mainly of an integrated D/A-converter supplemented by two opamps. This simplicity however, does not imply that the quality of this ‘USB audio-DAC’ has been compromised. On the contrary, we would like to say.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

R1 = 1k?5
R2,R3,R4 = 22?
R5 = 1M?
R6 = 470?
R7 = 680?
R8,R9,R13,R14 = 10k?0 1%
R10,R15 = 8k?25 1%
R11,R16 = 100?
R12,R17 = 220k?
C1,C6,C10,C20 = 10µF 63V radial
C2,C5,C7,C8,C9,C11,C19,C21 = 100nF ceramic, lead pitch 5mm
C3,C4 = 18pF
C12,C15 = 1nF5 1% polystyrene/polypropylene
C13,C16 = 270pF 1% polystyrene/polypropylene
C14,C17 = 3µF3 MKT (Siemens), lead pitch 5 or 7.5mm
C18 = 470nF, lead pitch 5mm
C22 = 470µF 25V radial
C23-C26 = 22nF ceramic, lead pitch 5mm
D1,D2 = 1N4148
D3 = green high-efficiency LED
D4 = red high-efficiency LED
B1 = B80C1500 (80V piv, 1.5A peak), round case
T1,T2 = BC557B
IC1 = PCM2702E (SSOP-28 case) (Burr-Brown)
IC2 = OPA2353UA (SO-8 case) (Burr-Brown)
IC3 = 78L05
K1 = USB connector, receptacle style B (PCB mount)
X1 = 12MHz quartz crystal
PCB, order code 000169-1
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