i want to measure telephone line voltage without affecting line
with a mcu
mcu will have independent power supply (obviously) therefore isolation is required
Ii was thinking about use of optocoupler's i tried a moc4020 with a 47k in series but drops voltage of line about 3 volts (from 48 to 45)
therefore i guess its not "best idea" !
does anoyne have an idea and/or link to some manual on this topic?