Do-It-Yourself Metal Detectors (Part 1)

 (The very first detector I owned was a Garrett Beat Frequency Oscillator [BFO] like this... a crude but extremely effective machine that nabbed me lots of "goodies" back in the day.)

I've said in the past that when it comes to gold (or treasure hunting in general) you'd probably be better off buying a machine from a well-known company rather than giving the do-it-yourself (DIY) approach a whirl. Well...I stand corrected.

Not long ago I received the following e-mail from from Arizona miner and metal detector enthusiast G.T. Blocker:

Helping the Next Batch

"Thank you, first and foremost, for your effort and time (as well as your patience) in the creation and maintenance of this web site" 

"On/off point: A few years back in the Gold Prospectors Association of America (GPAA) claims west of my home I ran across a family from Wisconsin. They had purchased the 'Mining Special' in the back of the GPAA magazine from some metal detector ad. They then "came on out to Arizona" to strike it big. I wish I had a buck for every time they asked if a yellow rock was gold. We 'pulled up stakes' and got the hell out of there. The point of your site is to help the next batch of them folks do a bit better. I admire that, hopeless as that dream may be...."
Taking Exception    
"I took the time to read through all of the years of your posts (including the treasure site you closed). I have mined since the mid-80s off and on and must say you know your shit. I especially love the 'fire and brimstone' aimed at the crooks out there."

"I did, however, take exception to one post. Within that post you stated that metal detectors were one of the pieces of gear that a miner can't build (you said it was best to buy one). I humbly disagree." The 'Hammerhead' pulse induction (PI) unit is one heck of a machine. I invite you to take a look at what  'home builders' are up to in the detector game."

Forum Links 

"Nearly everyone on the forum is more than willing to help 'newbies' build a working machine. are the links:"

("NOTE: I am 'GT Blocker' in the posts on the forum.")

"1st- the Geotech (Hammerhead) main site is:"

"2nd- The forum board site is:"

("A MASSIVE wealth of information on detectors and their tech!")

"3rd- I guess for credentials, here's my last post on the forum:" 

"I hope you keep the 'Bedrock Dreams' site alive."

"Thank you for you your time and indulgence."

Learning Something New
Despite my tendency toward hard-ass stubbornness, I am always open to being corrected if I'm wrong (which I was in this case) and to learning something new. I truly appreciate G.T. taking the time to straighten me out a bit and for bringing this info forward for the benefit of all. Not only that, but I have to give G.T. credit for his 'style' in straightening me out!

Metal Detectors
If you're interested in the "Hammerhead" PI machine or just want to learn more about DIY metal detectors, I highly recommend you take a look at the links G.T. provided.With the info you'll gain via these forums and links, you can learn to make your own Beat Frequency Oscillator (BFO), Very Low Frequency/Transmitter Receiver (VLF/TR), or PI machine.

(My main machine during the 1980s was Garrett's VLF/TR "Deepseeker." The housing was all metal and swinging it all day wore your ass out, but I found many thousands of dollars with a machine just like this one.)

I'll have more from G.T. to come, so please stay tuned.

Good luck to all.

If you liked this post, you may want to read: "Gold Detector Reviews: Garrett's 'Infinium LS' (Part 1)"

Questions? E-mail me at


  1. I too, used the Garrett VLF/TR "Deepseeker" in the 80's to find my first gold nuggets west of Quartzite, Arizona. There have been quite a few improvements since then.
    I disagree with G.T. Blocker. He seems to have a good knowledge of electronics. But, the average prospector is pissing in the wind if he thinks they can build any detector close to what is in production. Been there done that. I have an electronics engineering background. The Hammerhead PI that he mentions does ok in non mineralized ground for coins, etc. (Geotech Forum run by Carl Moreland) However, It doesn't as yet have a ground balance capable of handling the horrific ground of the gold fields unless G.T.B. has added one lately. So unless you have a lot of electronics knowledge and lots of time to waste, you are better off buying a detector and spend the time learning it and swinging it.
    Just my 2 cents!!!!!!!

    1. This comment is from friend and fellow gold miner "Rattlesnake" Jim.

  2. Your two cents adds a valuable element to this discourse on DIY machines. I know I wouldn't attempt a DIY machine...but that's me. The high mineralization in good gold areas is what's problematic---even for the best manufactured machines. Thanks much for providing your perspective on this...J.R.

  3. Hullo all, Carl from Geotech here. I will agree & disagree with some of the comments. In most cases, a DIY'er will not be able to build as good a detector as a production unit. A notable exception is in meteorite hunting where building a "hoss" PI detector with a 6-foot coil is often the better choice. For gold hunting, a ground balancing PI is not terribly difficult but there are almost no ready-to-build projects available. I have a "Hammerhead 3" project just about ready to publish but no time to finish it right now. There are a lot of other projects in development on Geotech so a really good DIY gold detector could be just around the corner. However, manufactured detectors continue to improve and will likely stay well ahead of the DIY route.

  4. Thanks for your input here Carl. The more comments and perspectives we get on this, the better the discourse. I totally agree with your last sentence. Best to you, J.R.


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