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Card Sound

Plenteous audio from a tiny micro SD Card

Card Sound
With a smartphone or an MP3 player it’s easy to play audio files, but generally not at room strength or if you can, only in wretched quality. The Card Sound project makes it possible to fill the room with music and have excellent sound reproduction! This lightweight and compact player also stands out for its modest quiescent current consumption and desirable extra features such as I²C and RS-485 control.
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* Analogue/digital supply voltages: 3 to 18 VDC / 4.5 to 12 VDC
* Analogue/digital current requirements: see Measurements panel
* Sinewave output power Pout into 4 or 8 Ohm: 12.5 W or 62 W (measured at 10.0 V peak-to-peak)
* Output: short-circuit protected max. 2 A
* Harmonic distortion: see Measurements panel
* Zero-value noise: around 1.4 mW
* Data formats: PCM 16, 24, 32-bit for each of 32, 44.1, 48, 96, 128 kHz Stereo
* Dimensions (L x W x H): 89 x 33 x 30 mm
* Weight without SD card: 26 g
Figures valid with a supply voltage of 5 VDC (digital) and 12 VDC (analogue) for a 1 kHz sinewave signal with 16 bits and 44.1 kHz sampling rate
Component list
FROM THE STORE
160460-1 Bare printed circuit board

Component List
Resistors
* : see Table 2
R1*,R4* = 0Ohm, thick-film, 5%, 0.1W, 150V, 0805
R2* = 120Ohm, thick-film, 1%, 0.25W, 200V, 1206
R3*,R10 = 1kOhm, thick-film, 5%, 0.1W, 150 V, 0805
R5,R7 = 100kOhm, thick-film, 5%, 0.1W, 150V, 0805
R6,R16,R19,R20,R23,R25 = 10kOhm, thick-film, 1%, 0.25W, 200V, 1206
R8,R24,R26 = 10kOhm, thick-film, 5%, 0.1W, 150V, 0805
R9 = 220Ohm, thick-film, 5%, 0.1W, 150V, 0805
R11 = 4.7kOhm, thick-film, 5%, 0.1W, 150V, 0805
R12,R13,R14 = 51Ohm, thick-film, 5%, 0.1W, 150V, 0805
R15 = 24Ohm, thick-film, 1%, 0.1W, 150 V, 0805
R17,R21 = 470Ohm, thick-film, 1%, 0.25W, 200V, 1206
R18,R22 = 27kOhm , thick-film, 1%, 0.25W, 200V, 1206
Capacitors
C1,C2 = 1µF, 63V PET, 5mm pitch
C3,C5,C13,C14,C15,C20,C21,C23 = 100nF, X7R, 10%, 100V, 1206
C4 = 10nF, X7R, 10%, 50 V, 1206
C6 = 4.7µF, Y5V, 16V, 1206
C7,C8,C31,C33 = 10µF, Y5V, 10V,1206
C9,C16,C17,C18,C19,C29 = 100nF, 50V, X7R, 0805
C10 = 10µF, X5R, 10V, 0805
C11,C12 = 22pF, 50V, C0G/NP0, 0805
C22 = 1000µF, 25V, radial, 20%, 10mm, 5mm pitch
C24 = 3.3 µF, 25 V, X7R, 1206
C25,C27 = 3.3µF, 63V PET, 5mm pitch
C26,C28 = 3.9nF, 250V, 5%, PPS
C30,C32 = 1µF, 16V, 10%, X7R, 1206
Inductors
L1 = ferrite bead 0.4Ohm, 200mA, e.g. Murata BLM21BD102SN1D
Semiconductors
LED1 = LED, green, 3mm
LED2 = LED, yellow, 3mm
T1 = BSS84 P-MOS, -170mA, -60V, 8Ohm @ -10V, -1.5V
T2 = IRLML5203 P-MOS, -3A, -30V, 98mOhm @ -10V, -2.5V
T3,T4 = MMBT2222, NPN, 40 V, 600 mA
IC1 = TDA7266 (audio amplifier)
IC2 = STM32F401RCT6 ARM Cortex-M4
IC3 = LD1117S33TR (3.3 V LDO, 800mA)
IC4 = SP3485CN (RS-422/RS-485 transceiver)
IC5 = CS4344-DZZ (24-bit 192 kHz audio DAC)
Miscellaneous
X1 = 12MHz quartz crystal, SMD, 5x3.2mm
K1,K2 = 2-pin pinheader, vertical, 0.1" mm pitch
K3 = 5-pin SIL pinheader, vertical, 0.1" mm pitch
K4 = 8-pin SIL pinheader, vertical, 0.1" pitch
K5 = Micro SD card holder, Hirose DM3CS-SF
K6 = 10-pin (2x5) pinheader, vertical, 0.05’’ mm pitch
S1 = Pushbutton, 6mm, single-pole NO, e.g. FSM4JRT (TE Connectivity)
Printed circuit board 160460-1 V1.5
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