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New Prototype Detector - My First Analog Attempt


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Pretty cool so far. Couple thoughts though. LED display might be difficult to read in the sunlight, maybe a backlight LCD?

Also on the coil where it mounts you might be better having the ears towards the center. Has less nosing down and better balance when swinging. Add a lateral rib on either side where the ears are to help absorb the shock so it isn't knock sensitive.

I been curious why someone hasn't done a double circuit using the same coil that run the same time so you could run an all metal mode and have a discriminator circuit to allow for iron audio overlay.

The Excal layout of controls is pretty nice. I like how you put a guard around the controls.

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   Great job SB,

  Looks to be a simple to operate lightweight design so far! The housing looks sturdy! Is it machined aluminum parts; other than coil and lower shaft? I hate plastic cuffs! Is the coil wire internal, or around the shaft? And is the unit going to be waterproof? Single frequency vlf? Is that the battery cap on the rear, and what kind of battery avilability and life do you estimate?

   If the LEDs are an issue in sunlight, as kac mentioned, they could be in a slightly inset housing to counteract this! That would also protect them from impact!👍👍

  

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11 hours ago, Sun- Boy said:

I apologize if this goes overboard on the images.

Well, I don't know about the storage size but the number of them is moderate compared to many who post photos here.

I like your enthusiasm and "get your hands dirty" effort.  "Well begun is half done" and you're past the 'well begun' stage already.  My main suggestion is to get a (prototype) unit up and running in the field and save the nicities for later.  (That may be your plan already.)  Air tests are known to be ideal and you likely will find differences with in-ground targets that lead to modifications.  So far the performance appears promising.  I look forward to your progress reports.

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Looking at the controls you have and saw gain is just high and low instead of a pot for finer adjustment. Many run their machines has high as they can and nudge the gain down to take in account emi and ground. Not sure how much of a monkey wrench that becomes in your design.

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This looks great! If you could I.D. check some very rusty crimp caps and rusty nails (those give a lot of us the fits). I'm curious what your numbers will do if you place your targets in (or under) a plastic shoe box filled with potting soil... I second the motion that kac made about the binaural (stereo?) audio. It may be feature creep, but it would greatly aid the brain to sort out at least *some* iron falsing...

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35 minutes ago, Johnny Crunch said:

...Place your targets in (or under) a plastic shoe box filled with potting soil...

I'm not a gardener which leads to this question.  Is potting soil just natural earth that has been dug up and put in a bag?  Or is it specially prepared organic material selected to 'feed' plants?  If the former then I agree, but the latter (depending upon if natural soil is included) may not contain the ferromagnetic minerals that affect real life detecting.  It's pretty easy to just bag some dirt from the backyard.  I've done that with ZipLock freezer bags.  You can fill them so that they have a more/less consistent thickness.  Mine are quart volume and when filled, sit flat with a thickness of approximately 1 inch.  Then I stack them.

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Way cool.   Looking forward to seeing more of your coil work.

HH
Mike

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Hi Guys, in answer to the questions:

Kac, 

LCD instead of Led's is an option, but that would mean interfacing to a screen which would mean a micro and programming which I'm not good at, so for now I'm stuck with led's

Coil mounting in the center, yep, that was how I designed my original one, but I wanted to keep the wiring short to the coil windings, but I do prefer the center mount one for the reasons you mentioned, I like the center mount for the next iteration.

I'm not real clear on the dual circuit you mentioned, not to sure what you mean.

I'm not sure why I didn't go with a pot for gain control, I think I didn't want the coil balance and gain to interact, but it's an option to explore.

Joe,

Aluminum parts would be great, but when the money comes out of your pocket....eh....time for rapid prototyping.  I use a place called 3D Hubs, I had them use MJF, Multi Jet Fusion, the parts are amazingly close to actual dimensions, probably +/- 2mils, they do a great job and a excellent prices.

The Cuff is an anderson labs, really good quality.

The Coil wire is running down the center of the shaft.

Waterproof?  Nope, it will be splash proof at best.

Single Freq. VLF, I would say it's kind of a hybrid VLF/CW - continuous wave, you don't have to swing the coil to get a signal.

Battery cover is on the back.

Batteries are 8 AA's, typical black plastic holder.

Battery life right now I think will be between 15 and 20 hours.

Led's are a little inset right now.

Materials I'm using on this model are carbon fiber tubes for all the shafts as well as the electronics/battery housing, if it don't work, it will be the prettiest non performing metal detector made! :)

GB,

I hear you, get it working now and make it pretty later....but I can't help it!!! :), gotta make it pretty..it's just how i"m wired :).

And thanks for the zip lock plastic soil idea, that will work well.

Johnny,

I will do some testing over the holiday weekend with some rusty nails, straight and bent, and I think I can find some rusty tin.

I'm still not to clear on the dual audio.

Thanks for the input guys, this model is pretty much set, but we improve as we go.

-S

 

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On 12/31/2020 at 1:25 PM, GB_Amateur said:

I'm not a gardener which leads to this question.  Is potting soil just natural earth that has been dug up and put in a bag?  Or is it specially prepared organic material selected to 'feed' plants?  If the former then I agree, but the latter (depending upon if natural soil is included) may not contain the ferromagnetic minerals that affect real life detecting.  It's pretty easy to just bag some dirt from the backyard.  I've done that with ZipLock freezer bags.  You can fill them so that they have a more/less consistent thickness.  Mine are quart volume and when filled, sit flat with a thickness of approximately 1 inch.  Then I stack them.

Yeah, I think you are right, GB. Potting soil is probably too unlike normal detecting conditions. I seem to remember something about it containing coal dust to make it darker, which might add another complexity to using it. My initial thought was it could be used as a standard for anyone running such a test, but that's a specious assumption on my part— anyone might be better served using the actual soil that they have to deal with normally, mineralized or not... Thanks for the constructive criticism!

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