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Metal Detector Power Sources - 8 AA Vs 4 AA


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Does anyone have an explaination for what advantage there is in using larger power sources? For example, take an MXT All Pro vs an F75 LTD. These are kind of similar in terms of how they perform and you might actually give an edge to the F75 LTD. Yet the F75 accomplishes this using 4 AAs with a battery life up to 40 hours. The MXT All Pro uses 8 AAs and has a battery life cycle that is maybe a little more than half the F75 LTD. Even if you consider that the F75 LTD runs on more modern circuitry, the new Whites MX Sport requires the same power and still only lasts roughly the same as the MXT while also not providing any depth advantage over the F75 LTD. So I'm wondering if maybe it translates into more depth on larger aftermarket coils, or if it provides any advantage at all. 

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Basically it's just battery life. The F75 will actually run on 2-AA batteries, but with (a little less than) half the run time. Newer detector designs use switching regulators that can boost the battery voltage to whatever is needed. You can literally run a detector on a single AA battery. Everything internal is the same regardless of the input voltage, so a bigger battery pack doesn't offer any more depth.

PI detectors can be more voltage sensitive as the TX circuit often runs directly off the battery.

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  • The title was changed to Metal Detector Power Sources - 8 AA Vs 4 AA

Thank you for that clarification. I had no idea such little voltage was required. In forums you'll often see guys point to a 4 battery (or equivalent) machine and say that it couldn't possibly perform like an 8 battery (or equivalent) machine. Obviously that's not true when you look at a machine like the F75 and what it can do. This is an area that I need much further study to understand. Intuitively a person would think, more voltage, more power, more depth, but then I remember reading an essay by Dave Johnson about diminishing returns and the size of the battery needed to get any further depth being unrealistic on machines of this kind. 

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