Re: gEDA-user: powermeter board, with less ground planes :-)

[Joerg <joergsch@xxxxxxxxxxxxxxxxxxxxx>]

DJ Delorie wrote:
>> Be careful. If for some reason the USB ground comes off and that's the 
>> only ground it'll be anyones guess where any capacitively coupled 60Hz 
>> will go. If it picks the data lines ... bzzzt ... poof. At least there 
>> should be some kind of bleeder.
> 
> Thanks for the warning.
> 
>> If by circuit panel box you mean the breaker box (or a sub-panel) 
>> legally you aren't supposed to do that AFAIK.
> 
> I suspect you're right, but then again, I don't plan on these being
> *that* permanent.  Ideally, they'd run off a transformer in the box
> and use radio or fiber to get the data out, but radio won't pass
> through a metal box that easily.
> 

Theoretically you could use a doorbell transformer, some come in 
breaker-panel compliant sizes. For data USB needs a direct connection 
and if that's all the R8C got, what can you do? Ethernet would be 
isolated but I don't know what's out there on the market to isolate USB. 
I think WiQuest had that but AFAIK they are gone. Some robotics places 
might have modules.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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