On Saturday 23 April 2005 07:53, Patrick EGLOFF wrote:
> Hi All,
> The nearest usable solution is to use a IL300 opto coupler that has a
> very linear transfer by using a feedback control. But this solution
> request at least one OP amp on the "hot" side. The "cold" side is
> isolated at 5300 V max for 1 s.
> Better than having all the display board with a HV rail but still not
> perfect !
I think there are many opto couplers that have enough linearity without
feedback to give you 5% or better accuracy and linearity, which is as good as
a cheap meter movement.
I'm also sure I've seen linearised circuits which have all the active
electronics on the 'cold' side. Maybe not with quite the precision of the
IL300, but do you need that? For example, use a second opto coupler where the
LED is powered from the output of a differential amp and the dff amp inputs
are the outputs from the two couplers. Provided the couplers are the same the
current in the 'cold side' LED will mirror the live one.
Have fun,
Steve
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