Linux’ed Telephone-to-VoIP Adapter
Quick Recipe: = add PIC, SLIC, Asterisk, Linux, FXS. No telco bill
Published in issue 410, February 2011
This open hardware & software project is a USB-connected interface that links a Voice-over-IP (VoIP) system to an analogue phone set or similar equipment like an analogue exchange. The powerhouse board works under Linux using the renowned Asterisk IP PBX software, and at a stroke enables you to use your home telephone set to connect to the VoIP world. Resistors
(default: SMD 0805)
R1,R3,R5 = 200kOhm
R2,R4 = 196kOhm
R6,R7 = 4.02kOhm
R8,R9 = 470Ohm
R14 = 40.2kOhm
R15 = 243Ohm
R16 = 200Ohm
R17 = 453Ohm*
R18A,R18B = 0.82Ohm*, shape 1206
R19,R20 = 18kOhm
R21 = 15Ohm, shape 1206
R28 = 37.4kOhm
R29 = 453kOhm*
R32,RCLR, RPGM, RUSR = 10kOhm
RL1 = 330Ohm, shape 1206
Capacitors
(default: SMD 1206)
C1,C2,C31 = 10μF 6V
C3,C4= 220nF 100V, shape 1812
C5,C6= 22nF 100V, shape 1812
C9 = 10μF 100V radial
C10,C14,C26 = 100nF 100V, shape 1210
C15,C16,C17,C24,C30= 100nF, shape 0603
C18,C19 = 4.7μF 6V
C25 = 10μF 25V tantalum bead
C105,106 = 680pF 100V
CDC1 = 100μF 10V radial
CDC2 = 100nF 25V
CO1,CO2 = 22pF
CUSB = 220nF
Inductors
L1 = 100μH 1A, SMD
L2,L3,L4 = 150μH 1A, SMD, type BLM18AG601SN1, 0603 shape
Semiconductors
(all SMD)
D1 = ES1D (SMB)
IC1 = Si3210-FT/GT (TSSOP38-LP), SiLabs, Mouser # 634-SI3210-GT
IC2 = Si3201-FS/GS (ESOIC-16T), SiLabs, Mouser # 634-SI3201-GS
IC3 = PIC18F2550-I/SO, programmed, Elektor # 100761-41, see [2]
LD1 = LED, green (1206 CHIPLED)
Q7 = FZT953 (SOT230P700X160-4N)
Q8,Q9 = MMBT2222A (SOT95P280X13-3N)
Miscellaneous
F1 = fuse, 0.75A, shape 1210
J1 = RJ-11/12 socket, PCB mount
JLVP = jumper or temporary wire link
K1 = 6-pin (2x3) pinheader block, 0.1’’
S1 = 2-way DIP switch, SMD
U1 = USB-A-H socket
X1 = 20MHz quartz crystal
PCB, Elektor # 100761-1, see [2]
* for phone cable length up to 2,000 ft. and V(ring) = 45 Vrms.
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Click below to download a PDF copy of this article from Elektor magazine. Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.
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