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Try a standard Bic plastic ball point pen medium tip - small brass tip with 1mm tungsten carbide ball. Steve Herschbach has used it for years as a standard for testing gold detectors - also easy to stick in the sand and hard to lose. - and, of course available everywhere.

Google Steve Herschbach bic pen and read what he has to say about it. It apparently behaves a very low conductive target. It presents in interesting test of the cut-off setting of a detector with iron discrimination - Might ve interesting for Manta

Here’s the results one guy got with his nugget detector on various targets (the POINT - lol - is to show how tough a target the pen tip is....)

”Bic Pen-3/4" 1/2 Grain (not gram) nugget 1" 1.3 gram nugget 5" . One tenth oz gold coin 8 1/2".. from Finds Technology Forum

     When I saw this posted the first time I tested some ball point pens from motels I had stayed at. Didn't have a Bic. Pen A(3.5us time constant) pen B(2.2us time constant) pen C(.65us time constant). Saw reply again the other day. Found  Dollar General had 10 BiC Round Stic medium pens for a dollar, 1mm tungsten carbide ball. BiC(2.1us time constant). Charts a little less than a 4grain nugget I have. Wondering why test above has BiC pen closer to 1/2grain nugget than a 4grain nugget. Maybe missing I'm something. Thought I would go to the source to ask. The time constant of ball point pens can vary a lot, wondering if the one I used is the same as used in the test above. Does look like a BiC Round Stic medium tip would make a good test target.


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Great info and all I can say is when I worked at my shop selling detectors this was the easy way to show a customer the difference between a coin detector and a nugget detector. A typical coin detector you can write on the bottom of the coil and get no signal. Any VLF nugget detector worth having gets a good signal. The bonus was since a hot VLF will detect your hand, the length of the all plastic shaft keeps your hand away from the coil.

What I was not doing was testing different pens to find the difference between pens. The choice of the particular Bic pen was purely accidental. It was more that pens like this are extremely common and can be found in a pinch for quick test purposes. Pens vary of course but as long as the same pen is used by one person to test different machines it works well. Comparing tests online with a person using a different pen not so much. I still use this test for quick and dirty comparisons.

Gold nuggets vary tremendously and I mean by a lot, so simply saying “X grain nugget” really says nothing. The pen does not equate to a particular nugget size but instead to quite a sizable range of nuggets. Some large specimen gold can give a very poor signal. The exact alloy composition and exact shape makes an amazing difference in gold nugget responses. That’s kind of the point in using the pen.

Where do nuggets in mineralized ground read? All the way from the ground response range into the ferrous range and then the non-ferrous range all the way up to silver dollar. That ground response? Could be a nugget. That ferrous response? Could be a nugget. Any non-ferrous response? Could be a nugget. That’s why no matter what people leave nuggets behind. Even if you dig every signal, the detector ground balance system will eliminate some from being detected.

The original Bic Pen Test post

Gold Nugget Target ID Numbers


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