Homebuild/homemade metal detectors DIY

Tim C

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Aug 6, 2014
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I have been pre-occupied these last few months with metal detectors. Despite owning 6, I was recently disappointed on a trip to the Golden Triangle, when the ironstone ground I had researched as a very likely gold area, was too hot for any production-line detector. I did however find small gold nearby with my Whites GMT. Since the introduction of vlf and Pulse Induction in the 80's, the older technologies of BFO (beat frequency oscillator) and IB (induction balance) have been ignored. So I have revisited these technologies with reasonable success. My intent is to scour all the ironstone gold areas where the Minelabs and others cannot even operate due to ground noise.
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This was my first etch. It is a "Matchless"IB metal locator, freely available online.
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On the right is my first detector. It will "see"a 5c piece at 15cm and 2.4g gold at 8cm, with a 15cm coil. Iron makes it go silent and non-ferrous materials have different tones.. For iron relics simply tune to the other side of the null point. The transistor of the circuit is taped to the radio at the strongest signal point, and around 1000khz. It has 2 operating frequencies-32 or 48 khz.
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This board is an Induction balance detector, with a built in AM receiver and amplifier circuit. I made a couple of mistakes, but it will eventually be another very handy unit. The 2 coils are partly over-lapped to produce a sweet spot with high signal. Ferrous is virtually ignored whilst non-ferrous can be heard on multiple and over-lapping signals. It can also discriminate by tilting one side of the coil towards the ground- either the ferrous or non-ferrous sensing side. I can get a faint signal from 5c at 25cm and 50cm for a 50c peice. It operates at 110 khz.
Also I have an assembled Surf-Pro PI DD board, with a ML 10x5 DD coil to set up.
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This will have 18650 batteries, a charge controller and a 1.5w solar panel. Hopefully by starting with the ML coil I will be able to get this working good.
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Garret Infinium, Whites Goldmaster, 2 cheapies. 2 more at my Ex's.
 
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Mark

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You are certainly one inventive guy Tim who thinks outside the box - great post!

So I gather you take several of these modified metal detectors with you on a trip not just as backup but also for different conditions?

I know a guy (lives in Gladstone) who makes a handy side income from gold prospecting - I have no idea what detector he uses but he seems to pay for just about every trip through the gold he finds (so he says). I've had a bit of opal mining prospecting experience but never used a metal detector to find gold (played with one to find mines once in the army).

I'd imagine it to be an excellent hobby with the country you'd see and the exercise/lifestyle plus the chances of striking it rich with a big nugget what a feeling that would be!
 

Tim C

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Aug 6, 2014
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Being stuck here without a licence I have done much research. I have 2 gps' and all the gear. The Whites Goldmaster has a black sand meter, which allows you to trace the "heavies"to the gold (if it's there). And it always pays to keep your eyes open, as I have said before. Areas where there is gold there may also be gemstones. Also many people look only at the ground in front of them when detecting instead of the geological formation underlying the topsoil.
Yeah I imagine even a modern plastic mine has some metal in it. My homemade IB can sense a 1/4 watt resistor at about an inch. But I think the Minelab F1A4 I would trust more. I think that's the one the Army uses.
 

Tim C

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On the map there is gold quite close to here, but nothing substantial. But anywhere in the Victorian Goldfields is relatively close for me. I already have my prospectors licence, and have joined PMAV, the Prospectors and Miners Association of Victoria. Just need the car licence back-25th November.
I know there's lots of gold in Qld too Mark! Go to Geoscience Australia/Interactive map/creat a map. Put in roads and rivers, population centres. Zoom to your area then add gold occurances in mineral occurances. You might be sitting on a goldmine, literally.
 

Tim C

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Aug 6, 2014
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Sorry Mark, wrong one. Google australianminesatlas(.gov.au). There definitely is gold near you. In mineral occurences drop-down menu select gold occurences.
 

Lois

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I loved Gold Detecting. Didn't do a lot. Still have my first and only nugget 12gms. Scared me silly when it went off. It was about 15 inches down. I reckon it was accidentally dropped there. Very old Chinese mine near Rockhampton. I am not fit enough or well enough to go out. But Everytime I think of selling my detector and gear, ( the pick comes in handy in the garden) I find myself thinking I will get well enough to get back out.