Ghoostknight
Headphoneus Supremus
Hello
i try to build something similar to the Ifi Idefender
it should have
- 3 usb connectors, one input, one output, one external power
- disconnect V from input and just use external power
- if possible disconnect GND too from input and use GND from external power
now to where it gets problematic... how can we leave ground connected but disconnect it as soon as the usb device is sucessfully connected? (since if gnd is completely disconnected most devices wont connect sucessfully) So in the end just D+ and D- should be connected from input to output, V and GND will come from external power input
- maybe current sensing on the output and disconnect ground after 1 sec?
- Can i use a isolation transformer and just connect ground to the output (and leave V unconnected)? or will this not work? (if just connecting GND wont work, how about a large resistor between secondary V and GND and use the GND this way?)
- Is this even a good idea? even if we get GND disconnected too, will noise be transfered over the data lines? or do most receiver chips reject noise on the data lines?
i know normally we should use usb isolators, but im trying to find a cheap solution/workaround (specially in the case of high speed usb), for example to disconnect my attached SSD to the raspberry pi beside the data lines, since i think connecting V and GND also introduces noise back to the system
i try to build something similar to the Ifi Idefender
it should have
- 3 usb connectors, one input, one output, one external power
- disconnect V from input and just use external power
- if possible disconnect GND too from input and use GND from external power
now to where it gets problematic... how can we leave ground connected but disconnect it as soon as the usb device is sucessfully connected? (since if gnd is completely disconnected most devices wont connect sucessfully) So in the end just D+ and D- should be connected from input to output, V and GND will come from external power input
- maybe current sensing on the output and disconnect ground after 1 sec?
- Can i use a isolation transformer and just connect ground to the output (and leave V unconnected)? or will this not work? (if just connecting GND wont work, how about a large resistor between secondary V and GND and use the GND this way?)
- Is this even a good idea? even if we get GND disconnected too, will noise be transfered over the data lines? or do most receiver chips reject noise on the data lines?
i know normally we should use usb isolators, but im trying to find a cheap solution/workaround (specially in the case of high speed usb), for example to disconnect my attached SSD to the raspberry pi beside the data lines, since i think connecting V and GND also introduces noise back to the system
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