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Subject: Re: Current Sensing Schematic
Date: Fri, 29 Nov 2002 01:25:33 -0000
NNTP-Posting-Date: 29 Nov 2002 01:25:35 GMT
X-Newsreader: Microsoft Outlook Express 5.50.4920.2300
"Spehro Pefhany" wrote in message
> On Thu, 28 Nov 2002 17:33:15 GMT, the renowned "Marc H.Popek"
> >Yes! Think about rogowski coil as the traditional solution to this
> Wouldn't get much output, would you, unless you separate the
> conductors of the line cord?
> Best regards,
> Spehro Pefhany
> "it's the network..." "The Journey is the reward"
> firstname.lastname@example.org Info for manufacturers:
> Embedded software/hardware/analog Info for designers:
get one of those bobbin miniature chokes like they used for telephone pickup
some10's or 100's of millihenrys in value, open constrcution on a ferrite
place this end on to the cable side so it gets to "see" one conductor (found
empirically by maximum output from the coil).
amplify the 60Hz output from the coil with an opamp ro transistor circuit
and use that signal to drive a re-triggerable monostable and/or comparator
(with R/C delay or hysterisis).
then you just set the gain of the amp or threshold of the comaprator to the
level required to detect the device is on/off .. (appropriate hysteresis
will prevent falsing and "chatter" especially with low current devices [
small difference in field ] ).
As the other guy mentioned, wrapping wire around the flex wont be reliable
as you will pick up both conductors and they will behave like a balanced
line so little "difference" will be detectable due to cancellation.
Kijoma solutions Ltd
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