On Oct 8, 2014, at 8:00 AM, Chuck Harris <cfhar...@erols.com> wrote: > Is removing the HPIB connector "the way"? > > Is anyone making a replacement panel that has a USB > and an RJ connector mounted?
I have looked into the mechanical issues of doing that, but haven't done a PCB layout yet. My plan was to include a USB isolation chip on the board so the USB connection has as much galvanic isolation as the transformer-coupled Ethernet. Also, I wanted to add a regulator to supply +5 on the internal side of the USB, driven from one of the large caps of the HP supply. That would provide some hold-up power for orderly shutdown of the Beagle on 5370 power-off. Alternatively, there would be some jumpers so the USB could bypass the isolator so the USB power could be supplied full-time from an external USB charger. That way the Beagle would run continuously for an "instant on" experience on 5370 power-up. There are some EMI/EMC and ground loop issues with all this. My guess is that if you use shielded Ethernet cable the shield/drain wire, and the shield/gnd wire of the USB, should probably be left floating on the 5370 end (i.e. non-shielded USB/RJ45 connectors on the PCB or making sure shielded connectors are isolated from the back panel). But I am no expert with such issues and would appreciate any advice. I kinda like PHK's solution: use a hole to get the cables out of there as quickly as possible. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
