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Topics - woody

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Technical / New GPX-4500 GPX-5000 Mods...
« on: February 15, 2015, 12:13:01 am »
Looks like we can get  40% plus on big targets with our newest mods... 40% also on small Gold.  Just need some field testing done...

This applicable to all GPX GP and SD2100 SD2200  detectors.

More information to be released via the news subsrciption on the home page.

Soon to be available is an upgrade that will allow GP and GPX series detectors to detect small gold similar to the capabilities of the SDC2300.

The Class D amplifier was a great idea but the problem was increased interference when using a large coil, Class A B amplifiers that use common amplifier topography generate high levels of hiss type background noise and this is particularly bad using metal detectors with low threshold volume.  We came up with a high quality class B design that has next to zero hiss and generates no extra noise. It only draws 5 milli amps with no input and thus has no noticeable effect on battery drain. This is a winner, to be released soon.

General Discussion / We have a Facebook page
« on: August 09, 2014, 03:16:01 pm »
We have a Facebook page/forum if you want to join, it's a closed group so if you want to post and stay hidden from the public gaze then come and join  There are 2666 members..

New Detector accessories / Interference filter
« on: August 09, 2014, 07:55:27 am »
I just finished a video on the interference filter i have been developing over the last few months.

Technical / Making the SD2000 SD2100 and SD2200 more quiet.
« on: August 06, 2014, 11:28:37 am »
These detectors are getting on on in years but they all are very good detectors, all can be modded up and detect in most cases as good as the newest detectors that are so very expensive.
The most simple fix is replacing the 150uh inductor in the switching power supply. Over the years the capacitors dry out and lose their electrolyte, this lack of capacitance causes circuit instability
and thus a noisy detector. Replacing the 150 uh inductor in the power supply with a physically  larger shielded type with less inductance of 100 uh does a number of things. First is raises the self resonant
switching frequency, this causes less noise as the internal power supply is more smooth in output. The higher the frequency the less ripple and those dried out caps can filter out the noise as the switching transitions
are less in amplitude. Also the detector starts faster, to me this because the existing inductor suffers ferromagnetic collapse at high start up inrush currents.  The supply actually runs cooler.

Watch this space, no one else can upgrade the F1A4 detectors to our new specifications... These are great for finding Quartz Reef Gold.

We have been busy. Have a series of 7 new upgrades coming out that will make these old detectors some of the deepest detectors available if not the deepest for large Gold and Treasure.

After testing the input stages on various detector I have found that many of the AD797 opamps with a spec sheet indication of 25mv DC offset is not the case when measured in some detectors.
Offset voltages in excess of 100mv are quite common.  Adding a potentiometer and trimming the Offset after 15 minutes run time to DC makes for a much more stable and quieter detector. As the first stages are DC coupled, reducing the Offset voltage makes for a much more behaved quieter detector. Frequency compensation can also be carried out to reduce Radio Frequency interference without degrading the low frequency slew rate or settling time of the opamp. 

Hot weather = Less Nuggets detected.
Cold Weather = More Nuggets detected.
Wet Ground = Less Nuggets detected.
Dry Ground = More Nuggets detected.
Night Time  = More Nuggets detected
Day Time   = Less Nuggets detected.

Why?   Who knows the answers?

I have been working on a complete new add electronic signal conditioning unit that will allow the detection of Gold at far greater depths and increased sensitivity to smaller Gold as well. Initial tests in the Lab are outstanding, now just have to go bush and do some more testing on real red hot ground. This new technology will open up the Goldfields like the early days of detecting.

General Discussion / Nugget Patches
« on: November 18, 2013, 07:03:42 pm »
Here is some nice Gold.

General Discussion / Nice big Gold Nugget from Victoria.
« on: March 09, 2013, 04:42:29 pm »
With Permission... Maryborough Gold.

General Discussion / Gold Gem and Treasure magazine
« on: February 10, 2013, 05:38:11 pm »
I will be writing monthly articles for Gold Gem and Treasure Magazine, so I will be writing about my 33 years as both a prospector and electronics designer.  There will be many articles that will greatly improve your detecting.. 

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