OPTOCOUPLER HCPL-901J
HIGH SPEED OPTOCOUPLER 100Mbs+
I just got a “USBee SX Logic Analyzer” but it is not electrically isolated from the computer. able to do (24 Million samples per second)
So, to fix this I want to use OPTOCOUPLERs, Zeners, transistors, and maybe Op-amps. keeping it simple.
The Result would be that I could then sample/generate signals up to 25volts.
This is why I don’t understand why no one has made an Ethernet version of one of these things yet… Ethernet by design is isolated I believe up to 2500V because it uses a transformer to couple the signals.
I guess I can understand the overhead of TCP/IP causing issues in some cases, but is it really that bad?
I think there are dedicated devices now which provide easy USB isolation. They are aimed at medical devices with usb interfaces.
Yes, I would suggest looking at a pre-built USB isolation device. There is more than just an optocoupler involved.
For a start, you need to power the device somehow, since you’ll need to disconnect the 5V power from USB. This could be as simple as a regulated 5V plugpack, or you could generate an isolated 5V supply from the USB 5V with an isolated switchmode circuit.
Then there is the issue that USB uses the same cable pair for send and receive, and only one can transmit at any one time. You’d need to think about how to connect the optocouplers so that the link is “transparent” to either both sides of the connection.
Not to mention all the “out of band” signalling that takes place on USB, such as the speed detection ‘chirp’ and so on. That and its 480MHz signalling, more then likely its not an opto isolator but some sort of transformer circuit that is used for that kind of data rate/frequency.