USB to 100BASE-FX Optical Fiber Network Card

Optical fiber is an intriguing technology, deployed all over the world connecting computer networks with the speed of light (well… almost).

Unfortunately, due to the inherent complexity of fiber network installation and management, optical fiber devices have never found their way in the hands of the user, and are usually deployed only by professionals for things such as backbones, long hauls or really fast interconnections.

Luckily enough, older optical fiber Ethernet components, especially 100MBit ones, are now available as a reasonably low price, so I decided to design a couple of USB to 100BASE-FX network cards just for fun and to learn more about working with optical fibers.

This project contains two complete hardware designs for USB to 100BASE-FX network cards, one with a 1×9 transceiver and one with an SFP slot. Both designs are based on the ASIX AX88772B chip, and fit in a compact Hammond 1551 series box.

Also, there are some useful links and information about designing with OF transceivers and SFP modules.

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Eagle Library for Hammond 1551 Boxes

Hammond Mfg is an American company who makes many different product boxes, mostly famous for their aluminum “Stomp Box” series, widely used for both DIY and commercial guitar effects units.

Browsing through the company’s products, you can find a whole range of small translucent plastic boxes that are really well suited for small electronic PCBs, and can give a good product-ish look to any hobby project.

In this post you’ll find some hints for designing PCBs for Hammond boxes, and an Eagle library with PCB outlines for some of them.
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2.4 GHz Inverted F Antenna Eagle Library

ISM radios for microcontroller are becoming quite popular in last years, and if you are designing with wireless radios you have a wide choice of transceiver in both sub-gigahertz an 2.4 GHz bandwidth.

If you choose to go for 2.4 GHz, you’ll have the benefits of a wide choice of radios, relaxed constraints in protocol design and a small size antenna.

Focusing on the antenna, 2.4 GHz radios usually have a differential output which have to be adapted to a 50 Ohm single-ended signal suitable for Wi-Fi antennas, which can be connected to the radio using an RP-SMA connector or directly embedded into the PCB.

This post shows a printed antenna design, kindly provided by TI/Chipcon, suitable for 2.4 GHz ISM radios. You’ll also find a link for an Eagle library with some tuning variant. Read more of this post