bklein Posted October 21, 2020 Share Posted October 21, 2020 I took a Fatshark battery pack that holds two 18650 li-ion cells and fed it into a buck converter adjusted to 6.86V output and used it to power my GP Extreme. I'm testing out a (TDI) Beach Hog coil at the beach. I have a Barrie Johnson Nuggettfinder MKII that has its own speaker/amp as well as speaker/phones volume controls. The buck converter has less than a volt dropout so it has a reasonable life of about an hour and a half. I did run into a problem though - if the coil got too near my scoop the detector overloaded. Something, the audio amp, the detector, I don't know which, overloaded and went into a low frequency oscillation. I thought I had fried the detector inputs but I shut everything down, waited a bit, and repowered and everything was fine. I can't duplicate the issue using an input signal from a signal generator into the Nuggettfinder - which has me scared now. It happened twice in the latter part of the battery life so maybe this is a factor? Is the GP Extreme designed to take overloads from large metal or is it at risk of frying? I bought mine with fried inputs and fixed it - don't want to do that again. I may move to a buck boost converter, put a 2S battery management circuit on the pack, and use larger 26650 cells which would keep the voltage stable and last longer. Link to comment Share on other sites More sharing options...
Steve Herschbach Posted October 22, 2020 Share Posted October 22, 2020 On 10/20/2020 at 11:23 PM, bklein said: Is the GP Extreme designed to take overloads from large metal or is it at risk of frying? You cannot fry any detector detecting manhole covers or even aircraft carriers. At least not if they are functioning properly. Link to comment Share on other sites More sharing options...
bklein Posted November 3, 2020 Author Share Posted November 3, 2020 I agree that a detector should handle overloads but it seems the GP Extreme has a history of front ends frying. Maybe from changing coils under power? Link to comment Share on other sites More sharing options...
Steve Herschbach Posted November 3, 2020 Share Posted November 3, 2020 Or just a weakness in a sourced component that quits randomly if you are unlucky enough to have one. Link to comment Share on other sites More sharing options...
bklein Posted November 11, 2020 Author Share Posted November 11, 2020 Quote Or another thing: I was running a Razorback Beach Hog coil that is meant for the TDI... I’ve read you can use GPx coils on the TDI but not the other way around. That would be a shame as then what is available as a bigfoot type coil for GPx? Link to comment Share on other sites More sharing options...
bklein Posted December 17, 2020 Author Share Posted December 17, 2020 I replaced the buck converter with a buck boost. I also replaced the batteries with better cells. Has worked fine since. The Beach Hog is awesome. Use the fuel gauge on the Fatshark to monitor cell voltage does not get below 3V/cell. Link to comment Share on other sites More sharing options...
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