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From: "John Jardine"
Subject: Re: Metal Detector
Date: Tue, 21 Jan 2003 16:02:23 -0000
NNTP-Posting-Date: 21 Jan 2003 15:47:57 GMT
X-Newsreader: Microsoft Outlook Express 5.00.2615.200
Nick Funk wrote in message
> Looking at making a very simple metal detector.
> I figure a one transistor oscillator with a High Q coil tuned to an
> un-used AM radio frequency. That way I can use the AM radio for a
> receiver. Doesn't have to be supper sensitive, but able to pickup 1
> galvanized inch pipe survey markers buried a couple inches.
> Just wondering which oscillator circuit would be best for this setup?
'Hartley' 'Colpits'. Doesn't matter really. Main thing is to tap into way
down the main coil to maintain a high working Q value. (maybe add a bit of
audio modulation to allow the signal to be heard!).
What I can't really see is how you will detect the tiny frequency shift, or
loss of resonant amplitude, on detecting metal?.
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