Path: utzoo!news-server.csri.toronto.edu!rutgers!ub!kitty!larry
From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: recording via induction: is it possible?
Summary: Use of clamp-on current probes
Keywords: inductive audio signal pickup from cable conductor
Message-ID: <4793@kitty.UUCP>
Date: 13 Mar 91 04:02:41 GMT
References: <3012@hexagon.se>
Followup-To: sci.electronics
Organization: Recognition Research Corp., Clarence, NY
Lines: 21

In article <3012@hexagon.se> daniel@hexagon.se (Daniel Deimert) writes:
>I was wondering if it would be possible to record an analogue signal
>(i.e.  the one in a loud-speaker's cable) on a tape recorder.  Or rather
>if the resulting signal is of good or poor quality.  S/N ratio?

	One can obtain a reasonably good signal through use of an inductive
clamp-on current probe intended for oscillographic measurement purposes.
Both Tektronix and Hewlett-Packard manufacture such probes, which permit
a conductor diameter up to about 3/16 inch.  It is necessary to amplify
the output of the current probe.  It is also important to remember that
the current probe goes over only *one* conductor of a cable.

>Would the circuitry needed be complicated?

	Not at all.  However, one must have a suitably designed probe;
an Amprobe AC ammeter probe intended for power measurements would function
rather poorly on audio signals.

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
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