cheapish optical USB isolator for faraday cage comms. - Page 1
Forum section: electronics / rf-microwave

author: Psi
author_rank: Super Contributor
timestamp: November 07, 2018, 12:46:18 am
content: I'm looking for a way to get USB comms through the copper mesh of a faraday cage. (Slow speed USB2)Best idea i can think of is some sort of optical link.Has anyone seen such a product available for under $100I could build something using LEDs and photodiodes, but best to try find something first.Ideas?

author: LapTop006
author_rank: Unknown
timestamp: November 07, 2018, 06:17:33 am
content: If you can get away with using Ethernet you can pick up a pair, and some fiber and a rasberry pi for within that budget.

author: MasterT
author_rank: Frequent Contributor
timestamp: November 07, 2018, 09:26:43 am
content: Digital USB isolator?https://www.digikey.ca/products/en/isolators/digital-isolators/901?k=&pkeyword=&pv183=1692&sf=0&FV=ffe00385&quantity=&ColumnSort=0&page=1&pageSize=25

author: Psi
author_rank: Super Contributor
timestamp: November 08, 2018, 06:29:33 am
content: Quote from: MasterT on November 07, 2018, 09:26:43 amIt's more getting the signal through the mesh without letting RF signals through the mesh.

author: Whales
author_rank: Super Contributor
timestamp: November 08, 2018, 07:29:10 am
content: For single-unit USB isolators (not want you want, isolated path is too short & inside the case):* USB 1.1 can be done cheaply.* USB 2.0 (480MBit) is expensive.* USB 3 is actually easier to isolate in some ways, but you still need the older standards included for things to work (IIRC).Can you use a device that bridges USB to ethernet? There are some commercial options IIRC, otherwise a single-board-computer might provide a better/easier option.Optical ethernet can be done with off-the-shelf multimode optics and SFP modules, these parts are not too expensive if sourced second hand off eBay. The switches with SFP slots, however, are a bit expensive if you have a home/hobby budget.Another option is single board computer + LED + phototransistor pointed to a pair of any old optic fibres doing UART/serial. You could do this with a tiny amount of parts and no special magic. There are probably off-the-shelf RS232 optical products too.What is your exact situation? USB measurement device for proprietary software?

author: Kalvin
author_rank: Super Contributor
timestamp: November 08, 2018, 07:38:52 am
content: USB-over-IP and an optical ethernet connection might be one possible solution:https://stackoverflow.com/questions/18837277/using-a-remote-hosts-usb-port-as-local-usb-linux-and-windowsI have not used this kind of technique myself, but it looks interesting.

author: Bratster
author_rank: Frequent Contributor
timestamp: November 08, 2018, 08:41:50 am
content: These guys have software that will run USB over Network, using a bunch of various devices as the actual USB host. Raspberry Pi, some different routers Etc.https://www.virtualhere.com$50 for a license though. Not sure how many devices.And you need to get a Raspberry Pi or something as well as the media converters for ethernet to fiber optic.A more roundabout way that would work is to get a steam link off eBay or whatnot(looks like they're around $30 depending on if you want new or used).You would still need the media converters for ethernet to fiber-optic,but a license for that Same software I linked above for the steam link is only $10 for three devices.The steam link has 3 USB ports plus HDMI and LAN.But it does require you to have the steam program installed on your computer for the steam link to connect to.And you need a display and mouse connected to the steam link to tell it to connect to the computer.If you don't mind that, the benefits of this is for about $40(plus the cost of the media converters)you could have 3 USB devices passed through to your computer and in a nice self-contained package.as opposed to $80+ by getting the license and a Raspberry Pi or something, plus possibly a case and a power supply etc.Although after typing all of this out I just realized that if you're doing something that's intended to be hands off inside the Faraday cage, it's probably better to go the separate license and Raspberry Pi or something way cuz that should be able to run unattended.the steam link would require you to have a display and a mouse to get things going.in any case you still need media converters to go from wired ethernet to fiber optic, however those aren't very expensive.Sent from my Fi Moto x4 using Tapatalk