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Linux’ed Telephone-to-VoIP Adapter

Quick Recipe: = add PIC, SLIC, Asterisk, Linux, FXS. No telco bill

Linux’ed Telephone-to-VoIP Adapter

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.

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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD 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.

Component list
(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
(default: SMD 1206)
C1,C2,C31 = 10?F 6V
C3,C4= 220nF 100V, shape 1812
C5,C6= 22nF 100V, shape 1812
C9 = 10?F 100V radial
C10,C14,C26 = 100nF 100V, shape 1210
C15,C16,C17,C24,C30= 100nF, shape 0603
C18,C19 = 4.7?F 6V
C25 = 10?F 25V tantalum bead
C105,106 = 680pF 100V
CDC1 = 100?F 10V radial
CDC2 = 100nF 25V
CO1,CO2 = 22pF
CUSB = 220nF
L1 = 100?H 1A, SMD
L2,L3,L4 = 150?H 1A, SMD, type BLM18AG601SN1, 0603 shape
(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)
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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