Funny story of metal detector technology

Since this forum is comprised of mostly md'rs who study and are versed on detector technology pro's & con's , and those that appreciate the ability of a detector to see through and around iron, thought I'd share this funny story. Of when/how the "lights went on" for me at least:

Back in 1980, when I was a senior in High school. I was hot and heavy into metal detecting. I had progressed by this time, up from a Whites 66TR (anyone here remember those?) to the "latest greatest" Garrett Groundhog. And was quite smug and proud of myself that, for the first time, I could pass foil, tabs, nails, etc...... It was a dream come true to effortlessly go to the parks and school yards and dig nothing but coins . Go figure, several of us were coming from the era of the Compass 77b's I'd seen, along with other BFO's and all-metal TR's (like my own 66TR). So when discriminators had come out by the mid '70s, they were far and away superior to us. Everyone was rushing to get 6000D's, for instance.

In 1980, our city tore out 2 blocks of downtown retail/commercial district street sidewalks. And word circulated quickly amongst us md'rs that this was the time to go! So 7 or 8 of us descended onto it with a passion . You could see all the "latest greatest" machines of that 1980 era being swung: 6000D's, Red Barons, and a smattering of VLF/TR's. Then off in the distance, I could see a guy swinging a 77b . Mind you: The 77b was 5 or 8 yrs. old by that time. Way behind the times in the "technological revolutions" that had occurred in the prior few years of that time. I remember smuggly thinking" "Poor soul with a dinosaur. Doesn't have discrimination. Pity him".

Later, the newspaper ran a local-interest story of the guys on the street sidewalk tearout detecting. And they had interviewed this guy swinging the 77b. He showed his spread of seated coins, barbers, tokens, in the newspaper story article. It was clear that he had spanked all the others of us by a 5x to 1 or better margin ! At the time, it made no sense to me. Afterall, we have the better machines with discrimination . RIGHT ? Afterall, we have better depth, RIGHT? (the 6000d, for instance, was doing double or triple the depth of the 77b WHILE discriminating, afterall). So it made no sense at all to me.

So I took this guy aside, and asked him how he could do it. Since he obviously had the oldest machine, no disc, etc.... The guy tried to explain to me that his 77b "didn't see the nails". But this made utterly no sense to me! Afterall, my Groundhog "didn't see nails", right ? And my other buddies 6000d's "didn't see nails". So I left in confusion. And just wrote it off to dumb luck.

It wasn't till several years later, talking to other long-timers, and began to understand the difference between "disc'ing out" versus "seeing through". I had never really understood the concept of "masking" I guess. Because at the time (late '70s and well through the '80s), the mantra was always "depth depth depth". And then add to that the allure of passing foil & tabs, and you can see why so many hunters just immediately ditched their "dinosaurs" in favor of the "latest greatest". And yes, for most types hunting they did indeed immediately increase the finds. (like park turf, for instance).

Even today, the immediate knee-jerk reaction by any newbie is going to be "how deep will it go?". And the concept of lacking TID, or getting only half-the-depth, is rejected in favor of the "depth" and "super TIDs". When the truth is, there's several types of hunt environment (iron ridden sidewalk tearouts, ghost-towns, etc....) where a person might be BETTER OFF with "half the depth" and "lacking mineral compensation" and "p*ss-p**r TID". Ie.: the lesser of 2 evils anyhow.



Edited 1 time(s). Last edit at 12/01/2016 04:28PM by Tom_in_CA.

Exactly why when an old and venerable club member was cleaning out his closet and offered me 2 Compass Judge 2's for $20 I jumped on it.
One doesn't work at all but it is good for parts, the other needs some TLC but still works and one day I will get it refurbished right.

If I only use it sparingly in iron but it finds me one great thing all worth it to me.
You need to have arms like Popeye to swing the thing for a long time, however.

diggwr27 Wrote:
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> You need to have arms like Popeye to swing the
> thing for a long time, however.


You know you can customize those, and make your own type wrist mount. Right ? Just rob the parts off any old cannibalized Fisher or tesoro or whatever, and you can make it into an "L" rod sort of configuration.



Edited 1 time(s). Last edit at 12/01/2016 06:02PM by Tom_in_CA.

Very desirable machine on the Thames foreshore .amazing at winkling out coins amongst the rubbish ..always wanted ,when others have faded into obscurity

The Compass 77b was also the top machine for UK farmland detecting in the 70s as well,it was the machine to be seen with,not alot else could touch it for performance also the Arado 120b detectors another top flight model,i actually still do have a couple of 120b's tucked away in a cupboard and still work very well but the weight is pretty heavy.

@Tom_in_CA,a very good read and a nice trip down memory lane into the bargain.

Junk and Disorderly Wrote:
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>..... a very good read and a nice trip down
> memory lane .....


Yup. When I got into it, as about a freshman in High school (15 or so yrs. old), I had bought a used 66TR. It had only been out of production for perhaps a year or two by then. And the school chum who got me into it was swinging a 77b (not the same person with the 77b in the story's OP). And we would go to the elementary schools plying our luck for silver, wheaties, etc.... And at that time even (1976 or '77-ish), we heard that there was such a thing as discriminators. But we bristled at getting them, for "fear that you might miss rings".

But after bumping into a few guys with discriminators (TR disc. at the time), it became clear to us that this was the route to go. So about 1979 or so, I got the Groundhog. In retrospect, I should have gotten the 6000D (which had just come out in about 1978). But we simply didn't know any better.

It's amazing how .... back then, .... it took an md'r YEARS to learn what was the "latest greatest". All you had to rely on, for any consumer reviews, was the magazines. And naturally any machine they "tested" would never get bad reviews. So we always looked with suspicion on any "review" in the magazines. And there was certainly no Q&A, or seeing one in person, etc... So back in those days, news travelled very slowly. I even saw 2 guys, back when I first started, still swinging BFO's !

But soon, by about 1979 or '80-ish, everyone was ditching the old "non discrimination" machines and going towards 6000'ds, the Red Baron spd, or various vlf/tr's.

Contrast to TODAY, with advent of the internet, and someone diligently studying can IMMEDIATELY sleuth out the "latest greatest". If something is truly a "better mousetrap", word travels quickly. Contrast to back then, you could be swinging something painfully out-of-date, not suited for a task, etc... and simply have no way to know any better.

So although my generation started when disc. (and even motion disc) was coming out, yet it was right at the "cusp" of the transition. And in some ways, those of us who've "been there done that", evolving with the times, have a unique perspective that persons of the last 10 or 20 yrs. can never fully appreciate.

Reminds me of an Atlantic City hunt years ago...fellow was hunting dry sand with an old green Compass Judge while several of us had modern units...Stopped to talk and he had several silver dimes, barber quarter and a nice gold ring.....guess experience counts....comes to mind.....

I have a couple of functional Compass 77B machines that I want to sell, in case somebody wants to experiment with them. They really do see through nails.

GREAT STORY!

Thanks for sharing Tom! Wish I had gotten into this hobby much sooner than I did!

I've got a 77b auto I use on CERTAIN sites and yes it's Nail dead..the 100Khz makes it hard to SEE them!!

need to do a video one day when I get a chance ...

Good info

Keith

“I don't care that they stole my idea . . I care that they don't have any of their own”
-Nikola Tesla

In my experience using 77b's, they will see through 1 or 2 nails ok. To get the coin underneath (albeit at a slight loss of depth, versus if the coin sat solo). But by the time you start to add a 3rd and 4th nail, you WILL eventually get masking, even on the 77b's. So the "trick" only works up to about 2 or 3 nails. It's not going to "see through" a RR spike, for example.

It should be noted that some of today's 2 filter machines can get close to the same trick. Like on the Tesoro silver sabre II, if I tune it to *just* loose nails, and then put a coin under a nail, it will get a positive conductive beep. And perhaps up to 2 nails (depending on the size nails, placement, etc....). So the 2-filter machines of today are a close comparison to the 77b. But the 77b did it a bit better. Ie.: "saw through" a bit more

It should also be noted that the Compass 77b wasn't the only all-metal TR that could do this. Even the Whites 66TR was the same concept. But the 77b did it better, deeper, and smoother IMHO.

The benefits of the 77b ended at that though. In all other ways they are truly a dinosaur:

a) Work poorly in minerals.

b) no other form of disc. (silver dollars and foil all sound the same)

c) a bear to keep balanced (especially over un-even ground).

d) lacking depth (compared to today's machines anyhow). Depth on a dime-sized target was about 6". Maybe 7" if you had perfect conditions and a good ear, like in dry white sand, perfectly balanced, etc.....

Tom, and others, if you are considering adding an older model TR to your detecting arsenal, try to check it out before investing your $$$. Also, I am referring to the 'conventional' TR and not the TR-Discriminator models. Yes, some of those can work pretty fair, but most of them come a little short of a really good TR.

Some of the best of them all were those made by Compass Electronics, more notably the Yukon series with the 77B being their 'top-of-the-line' at the time and most desired. I am thinning out some of my detectors, still, to include a very nice condition 99B. I also have a Coin Hustler 1 that is staying in my detector battery. A good friend gave it to me and it's in 98% condition and works perfect. The Coin Hustlers are smaller and lighter, but they are also simpler with one knob for tuning. They also lack a bit of 'fine tuning' performance as well because their tuner control only adjusts from a silent 'neutral' setting to a slight audio hum on the 'metal' or 'non-ferrous' adjusting range.

The 99B, like the 77B that has a needle display for intensity, has the one-knob tuner for Mineral then adjusting thru the Null range to the Mineral setting. Pick what you want to find, iron (Mineral) or pennies, dimes and other non-ferrous targets (Metal) and adjust for the proper Threshold audio Hum or raspy buzz and you're ready to go. These 100 kHz detectors are what really helped me with my Relic Hunting as well as urban Coin Hunting, but in either application, as you noted, it did take a little more patience to handle the falsing and nulling with irregularly shaped ground contour and the raising or lowering the coil for m a workable search height.

As for performance, I just did a double check of both my 99B and Coin Hustler, even though I knew the 99B would work better. Both have the original DD coils they were designed and sold with, the 8" DD on the 99B and 6" DD on the Coin Hustler.

I used a modern Zinc cent that mimics the size and conductivity of most Indian Head cents (USA talk here, of course) .

I also gathered five iron nails for this comparison test, including:

• A smaller, thinner nail that is 3¼" long 1/8" in diameter./

• A larger nail that measures 4½" long and just under ¼'.

• Three RR 'Date Nails" that measure: about 2¾" long, with widths of the '36' just under ¼" and both the '06' and '31' dated nails right at a thick ¼" in diameter.

Before I got to the two Compass models here in my den, I grabbed my Makro Racer 2 w/'OOR' DD coil mounted, Nokta FORS CoRe w/'OOR' coil mounted, and FORS Relic w/ 5½" round DD coil attached, and my Tesoro Silver Sabre microMAX w/6" Concentric coil mounted. I started out with the Silver Sabre µMAX at the minimum Discriminate setting. It uses the ED-120 Discrimination so the minimum is just a bit above (more than) iron nail rejection.

The Racer 2 and CoRe and Relic I adjusted the Discrimination to just barely ignore the iron nails. Just barely!

Once I knew I had setting to just barely reject the iron nails, I place the smallest , thinnest nail across the penny. I used the Tesoro w/6" Concentric coil and swept across the Nail-on-Coin lengthwise and did NOT get a response. I then swept across the Nail-on-Coin crosswise and GOT a good digable signal. I then checked all other detectors on this comparison and they produced good signals.

Testing step #2: I removed the shorter, thinner nail and replaced it with the larger 4½" thicker nail, then grabbed the Tesoro w/6" Concentric and repeated the test ... and did this a few times to verify the results! This time, I swept across the bigger Nail-on-Coin lengthwise and GOT a response both directions! But, when I then swept across the Nail-on-Coin crosswise I did NOT get a signal! Just the opposite results that I gtot with the same detector and coil with the thinner, shorter nail.

I checked all the TID Makro and Nokta detectors on this comparison, and they produced good signals.

Test #3: I replaced the smaller, thinner 3¼" nail across the center of the penny. Then, I laid the 4½" nail across and on top of the other nail, and this formed a crossing design with the nails, with the second poisoned 90° to the bottom nail. Now I love my Tesoro's, and I know what they can do for me and the times and places I like to grab them, especially for some 'flash cash' urban Coin Hunting. I also know how they can handle a lot of iron infested ghost town sites as they have served me well for 33½ years now. But all detectors do have their limits, and this is where the Tesoro flunked the test, producing NO digable responses from any direction.

Test #3 continued: With the Tesoro now out of the competition, I tried the Makro Racer 2, then the Nokta FORS CoRe, each with their own 'OOR' shaped DD coil, and finally the FORS Relic with the round 5½" DD coil. The Racer 2 did GET enough decent responses, in both 2-Tone and 3-Tone (I prefer 2-Tone when dealing with iron nails) to investigate. The FORS CoRe I felt gave equal to slightly better responses. My FORS Relic slightly out-classed the Racer 2 and CoRe with a little better response than the others from their borderline responses.

I guess that's why, even though I really enjoy my Tesoro's and Racer 2 and CoRe, the FORS Relic is my #1 general-purpose detector, especially for Relic hunting iron infested sites. All of these are in my regular travel detector arsenal, but my preference overall, if I had to; trim to only one unit, is the Nokta FORS Relic.

Test #3 continued: At this point I grabbed both my Compass 99B w/.8" DD coil, and Coin Hustler w/6" DD coil and checked the 2-Crossed-Nail set-up on top of the penny. Both detectors when adjusted for a slightly, proper, comfortable Threshold audio GOT a very good response from the coin from any direction, So, the challenge not was going to get even tougher!!!

Test #4: I added one of the thicker RR Date Nails by putting the head of the nail down and angling the point of the nail between the two other nails (sort of in a SW position across that 'pie' opening) and the point of the nail balanced on an angle across the larger 2nd nail on the stack, and the point of the nail just past the 1¢ coin. Both Compass TR's gave a good response to the coin when swept from ANY direction.

Test #5: I then added a 2nd RR Date Nail, this time to the lower SE section of the 'pie' so the head of the nail was on the surface, and the pointed part of the thick was angled so that it laid across the last nail and the point just passing the 1¢ coin. Both the TR's GAVE good responses, but the advantage of a louder and cleaner 'hit' went to the 99B with the finer tuning Metal/Mineral control circuitry. Both these TR's were swept from every direction, too.

The final Test #6: I used the last RR Date Nail and put it in the upper left quadrant, the NW section of the 'pie', but this time I laid the point on the surface and angled the nail upward so that it was now on top of all the other nail, with the nail 'head' above the coin's edge. Again, BOTH of the TR's DID give a response, but the Coin Hustler produced the weaker, but positive, audio 'hit.' The 99B was impressively louder, or a stronger audio response, and none of the other models on-hand (other than the Coin Hustler TR) could come close to that performance.

As Tom and others familiar with the good old TR performance stated, however, their 'can do' abilities are challenged by their need for proper coil-to-ground height control, maintaining a proper Threshold audio setting, and they are at their best in neutral, low, or possibly moderate mineralized soil compared with really nasty bad ground. There's no Discrimination or Ground Balance or other 'modern' features, but the original detectors that brought the conventional TR circuitry to the metal detecting game did have that one excellent ability to ignore most wire iron such as nails.

Monte

Monte, it is always a privilege for any of us to have you chime in on our posts ! I've said it before, and will say it again:

Some day, years from now, someone will collect all your posts from various forums, and compile them into a book. And will make a fortune selling the book. Your perspective of having done this since the 1960s, and graduating up through "all the ranks", gives you a unique perspective. And you are good at putting it all into understandable text, helping newcomers, etc.... So thanx again for taking time to chime in here !

Yes: the 99b and Hustler were similar in performance to the 77b. Just lacked "fine tune" , or the needle, or sens., etc... But the basic ability to see through nails, and the basic depth, were the same even on those "little sisters" to the 77b. And yes: None of this discussion is to be confused with the TR discriminate machines that were abundant in the late '70s to early '80s. We're talking about all-metal TR, not disc. TR. Despite the term "all metal", those all-metal TR's had the innate ability to null over small iron. And although they sounded off on larger iron (cast iron chunks, I-bolts, etc....), yet you could discern those by ear if you elected to. Because they had a "null" just before going over them . So you could almost discern both large and small iron alike.

If you ever have all those machines with you on one of the group hunts, and could repeat these tests on video (like if Brian "Cal Cobra" is present to make a video), that would be a great side-by-side test to be seen on a youtube video !

Thanx Monte !

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Tom_in_CA
Monte, it is always a privilege for any of us to have you chime in on our posts !

Always a pleasure with such an interesting topic. 'Thank You' for the kind words.

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Tom_in_CA
I've said it before, and will say it again: Some day, years from now, someone will collect all your posts from various forums, and compile them into a book. And will make a fortune selling the book. Your perspective of having done this since the 1960s, and graduating up through "all the ranks", gives you a unique perspective. And you are good at putting it all into understandable text, helping newcomers, etc.... So thanx again for taking time to chime in here !

Yes, I have traveled the long trail from 'stone age' detecting era to the present. But I hope to get my book finished up to beat folks to the punch of gathering up a pile of my 20+ years of Forum posts. I am working on it during our down-time wintry cold season.

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Tom_in_CA
Yes: the 99b and Hustler were similar in performance to the 77b. Just lacked "fine tune" , or the needle, or sens., etc... But the basic ability to see through nails, and the basic depth, were the same even on those "little sisters" to the 77b.

The Coin Hustler is a little more limited, when the iron presence gets even more challenging, due to the limited tuning ability as it doesn't have the full range since it lacks being able to adjust to the Mineral acceptance range. I have compared several 99B's to 77B's and while the 77B's do have the Coarse Tune and Fine Tune adjustability, a lot of times it's almost like splitting hairs to discern a difference. With the Mineral - to - Metal tuning adjustment, the 99B does show some performance 'edge' over the Coin Hustler. I just like my Coin Hustler because it is so compact and simple with the one knob for quick work of a small, dedicated area I want to scour at some old sites.

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Tom_in_CA
If you ever have all those machines with you on one of the group hunts, and could repeat these tests on video (like if Brian "Cal Cobra" is present to make a video), that would be a great side-by-side test to be seen on a youtube video !

I am planning to get with my youngest son when he returns from a business trip to Hawaii to do a series of videos that show-and-tell a number of detector comparisons. Naturally, I can't forget to demonstrate why the conventional TR (non-Discriminating) was such a key performer for me, especially from '71 all through the '70s and until the first good 2-Filter unit hit the market in mid-'83. While it doesn't get used a lot, it still gets put to work when desired or needed.

Monte