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Destroying the Harbor Freight Metal Detector to build a custom clad beast.

Huckleberry

Elite Member
Joined
Feb 11, 2021
Messages
861
Location
Missouri Ozarks
OK, so, since this is my first attempt at posting pictures, please bear with me.:?:

First, a pic of the finished detector...



A couple of years ago, I was gifted a Harbor Freight 9 Function Metal Detector, and, after playing with it in the yard and running some air tests, I concluded that while the electronics seemed adequate, the build itself was very poor, and would probably fall apart in short order.

The little detector languished in the corner for some time, until I stumbled across a post by TCosbyJr regarding his mod of the HF9FMD. Sadly, the pictures no longer exist, but his post was the inspiration. And so began my attempt to turn the HF9FMD into something a little more usable.



I had stumbled across a YouTube video from Mike at Wildcat Creek regarding a simple adjustment of a pot on the back of the circuit board, that will gain some depth. This pot can be seen in the photo. I marked the original setting with a paint pen before doing any adjustment, and suggest that if you try this, to do the same. Air tests “out of the box” were around four to four and a half inches. I conducted air tests while adjusting the setting of this pot, and got it up to seven and a half inches on coins. The referenced pot is the one in the center of the picture, the original position indicated by the white paint pen mark. As you can see, I didn't have to move it much.

The other pot has to do with ground balance, and the info that I could find indicated that this was best left alone. I found that there are other modifications that can be made to the circuit, but they come at a price, namely constantly fiddling with the settings while detecting, so I elected not to include these changes in my version.

I had an old toasted Garrett Money Hunter detector that I had picked up at a yard sale for parts for the princely sum of $8, which provided a dual 9V battery holder, mini toggle switches, some decent lengths of wire, as well as the adjustable lower rods. A trip to Walmart procured a wet box for around $6, and another to the hardware store for a short length of 1 inch pvc pipe, a couple of 45‘s, one end cap, and a coupling to facilitate connecting the rods from the old Garrett to the pvc upper. The pvc pipe and fittings were around $4. The arm cuff and stand were fabricated from a piece of 4 inch sewer pipe that I had laying around (unused :laughing:), cut to shape on a friends band saw.

At this point I could go into a long and boring explanation regarding disassembly, cutting, drilling, and stuffing everything into the wet box, but suffice it to say that procedures for a project like this largely depends on what you have laying around, or how much you want to spend. You basically just move things around until you are satisfied with the fit and function, then mount in place.



For my version, I chose to have the entire control panel (minus the angled part for the meter, which was cut off with a hacksaw :lol:), mounted inside the wet box. Accessible from the outside are a toggle for the on/off, a toggle for the pinpoint function, and the original headphone jack. I chose to house all of the controls inside the wet box (set the way I like), and use the exterior toggle to turn the unit on.



If you choose to do a project like this, I can offer a few pointers: The circuit board is double sided, and you can lift pads with too much heat, I avoided this by simply cutting the wires and leaving pigtails for connections. (hope that makes sense???) For example, I cut the wires going to the search coil, leaving about 2 inch pigtails leading from the board, making the connections later by soldering the wires back together and using heat shrink tube to insulate the connection. Take pictures of both sides of the board prior to disconnecting stuff in case you have to stop and come back to the project later. It was a fun project, though, not without it’s frustrations.:shock:



The final results:
It will find clad to around 7 1/2 inches. In tone mode, when the discrimination is adjusted so that a nail just does make a “breaky” sound, an interesting thing happens... you can place a nail (or pulltab) on top of a quarter, and the detector will give a high tone, apparently ignoring the nail. Nails alone obviously give the “breaky” tone. So, in the end I am happy with this project. I use it where depth is not an issue, namely places where I must use a probe for extracting targets. I also use it for a loaner, and it is a great conversation starter as well.:D Did you build that? Well.... sorta :laughing:

If you decide to try this, take your time, take photos, make notes, and above all, try to have fun doing it.

GL and HH
 
Pretty cool. Reminds me of the “remote” i made to power my kayak motor, lights, and fish finder.
c1c5bf9e28328882a93bb276fb35c1d9.jpg

b95b4eb1406238dcc595ca184b3864a9.jpg



Sent from my iPhone using Tapatalk
 
Interesting and creative. I would never have thought about it...

Unmasking with harbor freight.. maybe you have a little "Compadre" in your creation.
take it to a tot-lot and bring back some gold to show off. :thumbsup:
 
Interesting and creative. I would never have thought about it...

Unmasking with harbor freight.. maybe you have a little "Compadre" in your creation.
take it to a tot-lot and bring back some gold to show off. :thumbsup:

Thanks, that's actually my plan for tomorrow. Tot lot in city park, we'll see what happens.
 
Pretty cool. Reminds me of the “remote” i made to power my kayak motor, lights, and fish finder.
c1c5bf9e28328882a93bb276fb35c1d9.jpg

b95b4eb1406238dcc595ca184b3864a9.jpg



Sent from my iPhone using Tapatalk

I have that same soldering iron stand. Like probably everyone else who uses a soldering iron more than once a decade.
 
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