2 layers18 × 14.2 mm
2 layers73.9 × 73.2 mm
SkyFax
ME-IRL/SkyFax13Fax and data modems built around Skyworks's ISOModem chips.
- Size
- 73.9 × 73.2 mm
- Copper layers
- 2
- Thickness
- 0.8 mm
- Parts
- 98
- Nets
- 208
- Pads
- 429
- Tracks, vias
- 686, 97
- Pours
- 4
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 7 Sep 2023
- Updated
- 6 Aug 2024
Overview
SkyFax is an open-source printed circuit board by ME-IRL, from the ME-IRL/SkyFax repository on GitHub. It is a 2-layer board of 73.9 × 73.2 mm with 98 parts on 208 nets, routed with 686 tracks and 97 vias.
It is built around the 74LCX541WM, SI2494-A-FMR and SI3018-F-GS, with the 25LC640AT-E/SN, DS1818-5+ and HDS10M among its other parts. Its parts include 28 resistors, 18 capacitors, 7 ICs, 7 diodes and 5 transistors.
Main components
6
74LCX541WM
SOIC-20-300mil-40℃~+85℃ 10uA 24mA 24mA 2V~3.6V 6.5ns@3.3V,50pF 74LCX 8 Power-off isolation、Output enable、Hot-swap support Tri-State SOIC-20-300mil Buffers, Drivers, Receivers, Transceivers ROHSonsemiBuffer/Driver/Transceiver
SI2494-A-FMR
QFN-38-EP(7x5)0℃~+70℃ 3.3V 56Kbps SPI、UART QFN-38-EP(7x5) Interface - Specialized ROHSSilicon LabsInterface - Specialized
SI3018-F-GS
SOIC-16SOIC-16 Telecom Interface ICs ROHSSilicon LabsTelecom Interface ICs
25LC640AT-E/SN
SOIC-8-40℃~+125℃ 1,000,000 cycles 10MHz 2.5V~5.5V 200 Years 5ms 64Kbit Hardware write protection function、Built-in power-on reset (POR)、Built-in write enable latch (WEL)、Power-down/Power-up protection circuit SPI SOIC-8 EEPROM ROHSMicrochip TechnologyEEPROM
DS1818-5+
TO-92-3-40℃~+85℃@(TA) 1 100ms 3.06V Active Low Open Drain Simple Reset/Power-On Reset TO-92-3 Supervisor and Reset ICs ROHSMaxim Integrated (Analog Devices)Supervisor And Reset ICs
HDS10M
SMD-4P-55℃~+150℃@(Tj) 1A 1kV 5uA@1000V 60A 920mV@500mA Single-Phase Rectifier SMD-4P Bridge Rectifiers ROHSDiodes IncorporatedBridge Rectifiers
README
README.mdSkyFax Modems
Fax and data modems built around Skyworks's ISOModem chips.
Current functional version is 4.1 (see 3.0 below):
Case
I've also designed and printed a case to go with it. The STL files can be found under /case. Or on OnShape.
Version 3.0:
Simple Line Simulator
If you don't have access to a working landline or a proper telephone line simulator two modems can be connected back to back directly.
There are this and this pages, but I have found this circuit to work for me:
The voltage and resistance can be tweaked to provide ~20mA of current with the modem/phone off-hook.
If you'd like the schematic or just have a PCB made for the line simulator, check out the LineSim project included in this repo.
Once hooked up, you want to disable the dialtone detection with the command ATX3. Then you can just dial with ATDT on one modem and answer with ATA on the other.
See AN93 section 5.4 for details on all the AT commands supported.
Parts
98| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | 0.1uF | Capacitor_SMD:C_0603_1608Metric | C5, C6, C102, C104, C201, C202, C204 |
| 6 | 220 | LED_SMD:LED_0603_1608Metric | R104, R105, R106, R107, R108, R109 |
| 6 | LED | LED_SMD:LED_0805_2012Metric | D2, D3, D4, D5, D6, D7 |
| 4 | 10k | Resistor_SMD:R_0603_1608Metric | R201, R202, R205, R206 |
| 4 | Q_NPN_BEC | Package_TO_SOT_SMD:SOT-23-3 | Q1, Q3, Q4, Q5 |
| 2 | 0 | Resistor_SMD:R_0603_1608Metric | R15, R16 |
| 2 | 100k | Resistor_SMD:R_0603_1608Metric | R5, R6 |
| 2 | 20M | Resistor_SMD:R_0805_2012Metric | R7, R8 |
| 2 | 33pF | FaxCam:C_1808 | C1, C2 |
| 2 | 4.7uF | Capacitor_SMD:C_0402_1005Metric | C101, C103 |
| 2 | 56.2 | Resistor_SMD:R_1206_3216Metric | R12, R13 |
| 2 | 680pF | FaxCam:C_1808 | C8, C9 |
| 2 | FerriteBead_Small | Inductor_SMD:L_0805_2012Metric | FB1, FB2 |
| 2 | G*** | kibuzzard-65013388 | kibuzzard-65013388, kibuzzard-65013388 |
| 2 | G*** | kibuzzard-6501337B | kibuzzard-6501337B, kibuzzard-6501337B |
| 1 | 0.01uF | Capacitor_SMD:C_0603_1608Metric | C10 |
| 1 | 0.22uF | Capacitor_SMD:C_0603_1608Metric | C203 |
| 1 | 1.07k | Resistor_SMD:R_2010_5025Metric | R1 |
| 1 | 10nF | Capacitor_SMD:C_0805_2012Metric | C3 |
| 1 | 150 | Resistor_SMD:R_0603_1608Metric | R2 |
| 1 | 1M | Resistor_SMD:R_0603_1608Metric | R9 |
| 1 | 1k | Resistor_SMD:R_0402_1005Metric | R101 |
| 1 | 1uF | Capacitor_SMD:CP_Elec_4x3 | C4 |
| 1 | 2.49k | Resistor_SMD:R_2010_5025Metric | R4 |
| 1 | 2.7nF | Capacitor_SMD:C_0603_1608Metric | C7 |
| 1 | 22.1k | Resistor_SMD:R_0402_1005Metric | R102 |
| 1 | 25LC640AT-E/SN | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U4 |
| 1 | 3.65k | Resistor_SMD:R_2010_5025Metric | R3 |
| 1 | 47.5k | Resistor_SMD:R_0402_1005Metric | R103 |
| 1 | 536 | Resistor_SMD:R_1210_3225Metric | R10 |
| 1 | 73.2 | Resistor_SMD:R_2010_5025Metric | R11 |
| 1 | 74LCX541 | Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm | U6 |
| 1 | AZ1117-3.3 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U5 |
| 1 | Audio | Connector_PinSocket_2.54mm:PinSocket_1x03_P2.54mm_Vertical | J2 |
| 1 | CP2102N-Axx-xQFN20 | Package_DFN_QFN:SiliconLabs_QFN-20-1EP_3x3mm_P0.5mm_EP1.8x1.8mm | U3 |
| 1 | DS1818 | Package_TO_SOT_SMD:SOT-23-3 | U7 |
| 1 | D_Zener | Diode_SMD:D_SOD-123 | Z1 |
| 1 | ECS-2520MV-xxx-xx | Oscillator:Oscillator_SMD_ECS_2520MV-xxx-xx-4Pin_2.5x2.0mm | X1 |
| 1 | G*** | kibuzzard-6501316E | kibuzzard-6501316E |
| 1 | G*** | kibuzzard-650CCF10 | kibuzzard-650CCF10 |
| 1 | G*** | kibuzzard-6508DE41 | kibuzzard-6508DE41 |
| 1 | G*** | kibuzzard-6508DE31 | kibuzzard-6508DE31 |
| 1 | G*** | kibuzzard-650CCF19 | kibuzzard-650CCF19 |
| 1 | G*** | kibuzzard-650111BC | kibuzzard-650111BC |
| 1 | G*** | kibuzzard-6501311A | kibuzzard-6501311A |
| 1 | G*** | kibuzzard-6501314E | kibuzzard-6501314E |
| 1 | G*** | kibuzzard-6501317F | kibuzzard-6501317F |
| 1 | G*** | kibuzzard-65013408 | kibuzzard-65013408 |
| 1 | G*** | kibuzzard-650125E8 | kibuzzard-650125E8 |
| 1 | G*** | kibuzzard-6501315C | kibuzzard-6501315C |
| 1 | G*** | kibuzzard-650123DF | kibuzzard-650123DF |
| 1 | G*** | kibuzzard-650110F6 | kibuzzard-650110F6 |
| 1 | G*** | kibuzzard-65013126 | kibuzzard-65013126 |
| 1 | HDS10M | FaxCam:Diodes_Inc_4-SMD | D1 |
| 1 | M.2_B_Connector | SkyFax:AMPHENOL_MDT420B01001_2260 | J4 |
| 1 | M.2_B_Edge | SkyFax:M.2-B-KEY_2260 | J7 |
| 1 | Q_PNP_BEC | Package_TO_SOT_SMD:SOT-23-3 | Q2 |
| 1 | RJ11/12 | Connector_RJ:RJ12_Amphenol_54601 | J1 |
| 1 | SW_Push | Button_Switch_SMD:SW_Tactile_SPST_NO_Straight_CK_PTS636Sx25SMTRLFS | SW1 |
| 1 | Si2494-A-FM | Package_DFN_QFN:QFN-38-1EP_5x7mm_P0.5mm_EP3.15x5.15mm | U1 |
| 1 | Si3018 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U2 |
| 1 | USB_B_Micro | Connector_USB:USB_Micro-B_Amphenol_10118193-0001LF_Horizontal | J3 |
| 1 | ~ | Diode_SMD:D_SMB | RV1 |
The 95 most common of 98 parts.
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Questions
How big is the SkyFax PCB?
It measures 73.9 × 73.2 mm and has 2 copper layers, 0.8 mm thick.
What parts does the SkyFax use?
98 parts, built around the 74LCX541WM, SI2494-A-FMR, SI3018-F-GS and 25LC640AT-E/SN. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the SkyFax KiCad files?
From the ME-IRL/SkyFax repository on GitHub, at the commit this page was made from: the board is SkyFax.kicad_pcb and its schematic LineSim/LineSim.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the SkyFax design in my own project?
Its repository states no licence, so its author keeps all rights: ask ME-IRL before reusing the design.