Chris Ralph

Build a Do it Yourself, Homemade Metal Detector



Posted: Thursday, August 21, 2008

by
Nevada Outback Gems

A metal detector is an interesting device - it is able to sense the presence of metallic objects buried within the ground. They actually have gotten to be fairly inexpensive, and are available at sporting goods shops like Cabelas. However, still some folks always want to make their own, so I decided to write a bit about the challenges and possibilities of that kind of project.

Constructing your own metal detector is definitely not an easy project to do, but there are designs out there and available for those folks out there who possess the necessary knowledge and skills. Hey, if you're an electrical engineer and you can look at those circuit diagrams and figure with ease what the voltage is on the other side of those two capacitors and that resistor, probably building your own homemade metal detector will be no big problem for you. Perhaps you will design the latest and greatest new metal detector and we will all want to purchase one from you. On the other hand, if you've never assembled even the simplest electronics project before, and don't really know the difference between a capacitor and a transistor, you're going to be in for a whole lot of big trouble and headaches.

The project has a lot of issues of practical versus impractical; experience and knowledge versus ignorance, etc. Can it really be done? Can you build your own metal detector from scratch? There is no question that yes it can be done. However, if you are thinking of such a project, you should take some time to just learn more of the basics about how a metal detector works.

So lets consider the hard facts and get real: if you have no electronic skills and don't regularly build this type of electronics project, will building a metal detector be practical? The honest answer is: Probably not. It's basically a case where if you don't have experience with electronics and know exactly what you're doing, you'd be better off working at McDonald's on weekends because you would probably earn the money to purchase a manufactured detector long before you would get a homemade one built, tested and working properly. I actually had an electrical engineering class in college - so I know a little something - but I freely admit I'm no electrical engineer and personally I would never seriously consider trying to build my own metal detector - but those are just my thoughts. I'm not trying to discourage you; I'm just trying to stand up and face the truth.

On the other hand, if you are really serious, and have the requisite electronics experience, tools and all the testing equipment necessary to build such a project, I am providing a website that will provide you the schematic circuit diagram plans and design you need. You can also purchase a pre-printed board for the project from the web site author. He also has loads of information on metal detectors in general. Will the finished metal detector be every bit as good as the best ones for sale in the metal detector shop? Probably not, but they definitely do work. I wish you the very best of luck in your efforts, and if you do take this path and succeed, send me an email.

Here is the web site with the plans and design to build your own metal detector. I'd ignore the designs for historic types of detectors such as the BFO type units. There are both PI (Pulse Induction) and VLF (Induction balance) detectors described here.

Metal Detector Design Schematics Information: http://geotech.thunting.com/cgi-bin/pages/common/index.pl?page=metdet & file=projects.dat

For More information on prospecting for gold and how you can do it, check out the author's Prospecting encyclopedia at: http://nevada-outback-gems.com/prospect/chris_prospect.htm

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Top-level comments on this article: (1 total)
» left by Gregory Lewis
 3 years 114 days ago.
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What I liked about this article was that I have built my own metal detectors from scratch, my own design (I have an associates degree in electronic engineering, and am a long-time electronics hacker).

The metal detector comes down to one fundamental principal: inductance, as in using a coil.

When you understand that the inductance of a coil is moderated by the presence of metal, there is really no end to the kind of design you can use. Standard metal detectors use an AM interference schema, which means that when you move an un-shielded AM radio around metal objects, the "fuzz" noise changes slightly. When you have two AM amplifiers, and one is subjected to metal, the other is not, the interference of the first to the stability of the second causes the needle or light or sound to change. But, basically all you have to do is make a coil change its inductance, as measured in micro-Henries, and amplify that change however you like. I imagine it would be very easy to get crazy and computerize the output to some software, even put the graph on the web or over the internet use a cheap programmable controller kit.
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