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Hi all,
I've been messing around building metal detectors sporadically over nearly 30 years. First up was a BFO design out of an electronics mag, then I built the PE Magnum (an IB machine) - I had it working but had trouble actually mounting the coil. I also *started* building the PE Sandbanks (PI) after talking to someone who had one, but fell foul of the now infamous DC/DC step-up power supply so shelved it for 20 years or so. I now gather it's possible to bypass this stage, which would make life easier.
I've just revived my interest in these machines; I've still got the components so have made a start on the Sandbanks again. As we speak, I'm awaiting delivery of some PCB developer to etch a new board for it since the old one didn't survive de-soldering too well . . .
In the case of the two I built - the BFO one and the IB Magnum, I found that the search head was problematic. The instructions for the BFO one specified a frisbee for the coil housing, and the Magnum's coil was mounted on a Melamine picnic plate. The frisbee was too flexible on the one hand, and the Melamine, while rigid, was heavy and brittle on the other. Discounting the BFO detector on the grounds that is isn't a 'serious' machine, I also found that the stem of the Magnum, being made of PVC waste pipe, was too flexible and allowed too much flop. Also, it's difficult to take seriously a machine which is constructed from picnic-ware and plumbing fittings - the aesthetics need to be right to satisfy me
Thinking about it now, I think that in terms of its physical characteristics, a carbon fibre housing would be ideal. It's light and strong, and could be so designed as to be very rigid by virtue of its shape. The stem, too, could be made of carbon fibre - I've seen that others on these forums have used carbon fibre fishing rod sections, or I could make a collapsible mandrel and make my own.
I know that carbon fibre is electrically conductive - would that make it unsuitable to house a search coil in; i.e. would it have any screening effect in either a PI design or an IB one?
Any thoughts or advice?
I've been messing around building metal detectors sporadically over nearly 30 years. First up was a BFO design out of an electronics mag, then I built the PE Magnum (an IB machine) - I had it working but had trouble actually mounting the coil. I also *started* building the PE Sandbanks (PI) after talking to someone who had one, but fell foul of the now infamous DC/DC step-up power supply so shelved it for 20 years or so. I now gather it's possible to bypass this stage, which would make life easier.
I've just revived my interest in these machines; I've still got the components so have made a start on the Sandbanks again. As we speak, I'm awaiting delivery of some PCB developer to etch a new board for it since the old one didn't survive de-soldering too well . . .
In the case of the two I built - the BFO one and the IB Magnum, I found that the search head was problematic. The instructions for the BFO one specified a frisbee for the coil housing, and the Magnum's coil was mounted on a Melamine picnic plate. The frisbee was too flexible on the one hand, and the Melamine, while rigid, was heavy and brittle on the other. Discounting the BFO detector on the grounds that is isn't a 'serious' machine, I also found that the stem of the Magnum, being made of PVC waste pipe, was too flexible and allowed too much flop. Also, it's difficult to take seriously a machine which is constructed from picnic-ware and plumbing fittings - the aesthetics need to be right to satisfy me
Thinking about it now, I think that in terms of its physical characteristics, a carbon fibre housing would be ideal. It's light and strong, and could be so designed as to be very rigid by virtue of its shape. The stem, too, could be made of carbon fibre - I've seen that others on these forums have used carbon fibre fishing rod sections, or I could make a collapsible mandrel and make my own.
I know that carbon fibre is electrically conductive - would that make it unsuitable to house a search coil in; i.e. would it have any screening effect in either a PI design or an IB one?
Any thoughts or advice?
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