 Ground Meter?
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ShawnLG
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Registered Member #286
Joined: Mon Mar 06 2006, 04:52AM
Location:
Posts: 399
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"When nothing is near the coil I can hear some tones and noises and as I move hand near it, the tones and noises change like tuning an old AM radio. Touching any wires changes the output a lot too."
This means that your amp has unwanted feedback and is self oscillating. You will need to isolate the input and output circuits to help stop the oscillation.
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Simon
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Registered Member #32
Joined: Sat Feb 04 2006, 08:58AM
Location: Australia
Posts: 549
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Alan wrote ...
I also presume that frequency analysis would have to be done to shift frequency's to high or low up or down, something like a logarithmic curve between EM frequency and the frequency you could hear would be good.
Frequency shifting is not that complicated (in principle). To shift by, say, 500Hz, you multiply (modulate) the signal with a 500Hz tone and filter out all the high freqencies.
For more theory/circuits, search for "downconversion" and "upconversion".
I don't know if this helps your app.
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