> Russell McMahon ha scritto:
>> - Aim is to detect that mains is within desired voltage range.
>>
>> - Transformer secondary output is available.

It is not unusual that the trade-off for a transformer is that the
secondary voltage drops 20% or even more under the full load. If this
is the case, it may cause some difficulty to "measure 220V mains
voltage with some coarse accuracy, say 1-2%" using the available
secondary output.
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