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Hi Everyone,
These recent posts cause me pain. There is nothing so frustrating as an enquirying mind wanting to understand and achieve - and being thwarted.
Where is Carlos?? I know he builds the Proscan and substitutes an '740 mosfet for the output device. Personally I have not dabbled with this circuit - it is dated to hell. P.I. is not so simple as may be made out. Pass a coil - or coils over a target and observe. The target influences the Tx coil, then influences the Rx coil. Negative responses occur - not just positive ones.
Stewart's circuit (microprocessor) is not viable (integrating/indicating problems) and Trevor's Goldpic is not so great in that there is excess sample delay) There truly does not appear that there is a current circuit available.
I appreciate that Eric has posted a front-end, oscillator, and power supply circuit - he once also hinted about posting an integrator circuit!! That would be really nice for the current fiddlers.
Myself? Lost in multiple-sampling, absolute-value, and low-pass adder circuits. Having fun - and learning.
My most successful detector? A discriminating Induction-Balance design per Silicon-Chip Magazine(Australian) (Carl has not posted this circuit, but contact me for a copy per snail-mail) I have played with this circuit from here to there - as Eric recently admitted (?)
a good I.B will see off a P.I. machine in some situations. The figure he quotes (cf a Goldbug2)
would require the P.I. machine to provide a 5uS Tx pulse and a sample delay of 1uS - don't think that even he can approach this with his products.
P.S. I own a Goldbug2 - it is useless in anything resembling damp. It is hot,hot,hot anywhere else.
graeme
These recent posts cause me pain. There is nothing so frustrating as an enquirying mind wanting to understand and achieve - and being thwarted.
Where is Carlos?? I know he builds the Proscan and substitutes an '740 mosfet for the output device. Personally I have not dabbled with this circuit - it is dated to hell. P.I. is not so simple as may be made out. Pass a coil - or coils over a target and observe. The target influences the Tx coil, then influences the Rx coil. Negative responses occur - not just positive ones.
Stewart's circuit (microprocessor) is not viable (integrating/indicating problems) and Trevor's Goldpic is not so great in that there is excess sample delay) There truly does not appear that there is a current circuit available.
I appreciate that Eric has posted a front-end, oscillator, and power supply circuit - he once also hinted about posting an integrator circuit!! That would be really nice for the current fiddlers.
Myself? Lost in multiple-sampling, absolute-value, and low-pass adder circuits. Having fun - and learning.
My most successful detector? A discriminating Induction-Balance design per Silicon-Chip Magazine(Australian) (Carl has not posted this circuit, but contact me for a copy per snail-mail) I have played with this circuit from here to there - as Eric recently admitted (?)
a good I.B will see off a P.I. machine in some situations. The figure he quotes (cf a Goldbug2)
would require the P.I. machine to provide a 5uS Tx pulse and a sample delay of 1uS - don't think that even he can approach this with his products.
P.S. I own a Goldbug2 - it is useless in anything resembling damp. It is hot,hot,hot anywhere else.
graeme
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