Comments on: USB Isolation

By: Buts

Buts — Wed, 18 Aug 2010 12:30:47 +0000

Nice, but only full speed (=12 Mbps). Does anyone has a high speed (=480 Mbps) solution ?

By: esdk

esdk — Thu, 05 Aug 2010 16:31:10 +0000

Could you add a link to the other USB-adaptor:

Http://electronics-shop.dk/usb-isolator

By: Stackbit

Stackbit — Fri, 09 Oct 2009 11:23:23 +0000

THis is also very useful with connecting with PBX with usb ports for programming. Siemens HiRise 1100 series only allows a USB conection with a proprietary insulating dongle ( a ps/2 connector on the PBX side).

With this you can just make a connector change-over, and use the insulator in the middle! Thx for the great hack!!!

By: Wwhat

Wwhat — Sat, 19 Sep 2009 03:01:30 +0000

Oh one more thing (last one I promise), if you have issues with shorts you could simply use some diodes at the USB connector, cheap and quick, no need to go through lengths like this project does.

By: Wwhat

Wwhat — Sat, 19 Sep 2009 02:57:29 +0000

Hey I suddenly see hackaday accepts caps now, no more stripping? I wonder what else it accepts now.

By: Wwhat

Wwhat — Sat, 19 Sep 2009 02:54:58 +0000

Certainly useful for something, but I’m not sure it’s quite up to stopping mains from doing damage, I don’t think that’s quite the idea, just because something isolates signals and 5v doesn’t mean it’ll stop everything you know.

By: Nick H

Nick H — Fri, 18 Sep 2009 20:31:45 +0000

This seems like it could be useful for DIY “medical”/monitoring projects which require safe coupling with a human body, eg OpenEEG and the like. IIRC, they usually use an RS-232 serial port because it’s easier to use optoisolators on the lower speed signals.

By: James

James — Fri, 18 Sep 2009 17:58:19 +0000

This would probably be good for making a control circuit to turn my woot lights on and off via software.

By: Odin84gk

Odin84gk — Fri, 18 Sep 2009 17:56:37 +0000

@Oleg Mazurov

The device inserts the same timing delay as a USB hub, but it does not react like a hub. The high/low speed settings on the device takes care of the wait states between signals and the artificial delays required to keep the proper timing requirements. This is why both sides have a separate jumper to set the speeds.

By: Odin84gk

Odin84gk — Fri, 18 Sep 2009 17:47:17 +0000

This is a great reference design, but it does NOT provide mains isolation. The PCB layout clearance is only 1.63 mm, which means it can only isolate 150 volts DC at less than 1 watt of current.

The board should be redone with at least a 5.5mm between the primary and secondary side of the isolation to provide the isolation specified in the datasheet.

Here is a rule of thumb: If you are working with a component that provides isolation, do not create copper traces that are closer together than the footprints for the part.

By: Awesomenesser

Awesomenesser — Fri, 18 Sep 2009 16:43:43 +0000

My friend fried a $350 mother board and a atmel programmer when he was programming his 12 channel 120v dimming xmas light controller. Then I unfortunantly let his borrow my spare motherboard and the next night he took it out along with a another borrowed programmer.

This was because he forgot to unplug the programmer and I guess the USB doesn’t like 120V. Oh and right after this he found the mistake on his PCB. But didn’t have a computer to reprogram it.

Luckily asus didn’t know and replaced both motherboards.

So yes this would be a great gift for him.

By: strider_mt2k

strider_mt2k — Fri, 18 Sep 2009 16:39:18 +0000

Nice! (And nice work there too!)

Isolation lends itself to not blowing up all KINDS of cool stuff! ;)

By: Buzzkill

Buzzkill — Fri, 18 Sep 2009 16:35:42 +0000

@cantido

Home automation
Lighting controls
Relay or dimmer packs
etc, etc, etc.

There are lots of projects for using USB around mains voltage. And if you are rolling your own, then there is always the opportunity to cross a whire someplace, bridge a solder joint, or just plain user error that could drop mains voltage onto the logic side of board.

By: cantido

cantido — Fri, 18 Sep 2009 16:26:37 +0000

@hpux735

Most host controllers disconnect the port if they sense a short or similar. I’ve created shorts on my Macbook’s(Running debian) ports a few times and there’s a nice message in dmesg saying that the host controller detected a short and disconnected the device.

@Adam

W(hy)TF would you have mains around your USB projects? I wouldn’t worry about blowing a port up, I’d worry about blowing yourself up! :P

By: svofski

svofski — Fri, 18 Sep 2009 15:28:50 +0000

on my computer shorting out usb power to ground may cause a reset condition. i wonder if this device protects from such events.