[time-nuts] Re: Another reason to monitor line frequency :) - My AC measurement project & question

[glen english LIST]

hear hear.stick to galvanic isolation or better  -

On MF/SW broadcast sites for this we used optically coupled sensors.

The mains supply is simply intensity modulating an opto isolator ( a 
pair actually for both sides of the waveform) .. They can with stand a 
fair degree of overload and its likely something else will flashover 
first with slots in the PCB. The opto was used in a linear mode.  lots 
of effective R in the emitter . didnt bother with saturation prevention 
diode B-C because the recovery was (still) fast compared to the 50/60Hz.

-glen.

On 23/01/2022 6:15 am, willl will wrote:
> On 1/21/22 7:00 PM, Robert LaJeunesse wrote:
>> Stick with the transformer. The use of a capacitive divider is predicated
> on the line waveform always being a sine wave. Dream on! All it takes is
> one good spike down the line, maybe only 20-30V amplitude, and your
> capacitive divider passes it right on to that ADC that has a much lower
> (3.3V?) limit. Guess what goes poof?