IB metal detector using signal generator

[reptooyep]

Hi,
What do you think of the idea of using a signal generator such as XR2206 to generate an ideal sin wave for TX ?
This can help tuning the coil cause with a simple pot, you can modify the frequency ...
Regards

[WM6]

Good idea - to test audio stages - but not for detectors.

[reptooyep]

Why? The xr2206 looks pretty easy to use.. The best TX signal will produce the best RX ?
With my TGSL, i can see that the collpits osc produce a distorded signal (the positive half sine is larger than the negative).
That gves me hard time for coil ballancing. A nice signal would help ... In my situation.
Does anyone has teted this before ?

[WM6]

You are trying to get at TX as much stable signal (by frequency and amplitude) as possible.
This will not work with metal detector in most design. Rock hard signal oppose to sensitivity.
In case of VLF/IB (induction balance) key to good sensitivity is in loose stability (loose balance).

[Skippy]

"The best TX signal will produce the best RX ?"
Agreed, and the XR chip won't produce the best TX signal. You need stability, precision, low phase noise, those sort of things. The non-sinusoidal artefacts you may see on a machines transmit signal are always at higher frequencies, either higher harmonics or much higher parasitic oscillations. These either get filtered out by the first amplifier stages, or the synchronous detectors and their subsequent low-pass filters will remove them.