[time-nuts] Frequency counter recommendation

[Magnus Danielson]

On 12/19/2010 11:47 AM, Javier Herrero wrote:
> Hello
>
> El 19/12/2010 11:13, Magnus Danielson escribió:
>>
>>
>> To achieve meaningful isolation, it should be optical. Transformer
>> isolation has a few issues to get right...
>>
>>
> What about digital isolators, lile ISO7220, ADuM1200 and so?

Need to look at it. But essentially, during normal operation common mode 
isolation isn't all that hard. The problem is that during failure mode 
can what should be a common mode voltage and current become diffrential 
mode, which jumps straight through the transformers as a transient and 
that will burn the receiver anyway...

I've seen people burn their Ethernet port by hooking in an ISDN line to 
the wrong connector.

A wrapped solution like the ADUM1200 puts more stuff between the 
transformer and actual receiver... so maybe you save the receiver, but 
you might toast the isolator.

For an optical isolation you might toast the transmitter, but that's 
about it. Probably that would be the least of your problems when it occurs.

Cheers,
Magnus