Compass Coin Magnum? Anyone ever modify this detector model???

[Melbeta]

The Compass Coin Magnum, with VLF all metal mode, and VLF "NO-MOTION) Discrimination mode. It was advertised by Compass as being one of the machines that will find small U.S. gold coins. It used three signals rather then just two signals, and had a secret blanking potted board.

Did anyone ever try to modify this unique metal detector? I know of a couple in Denver CO who used two of the Coin Magnums, and literally found a fantastic amount of 1859 coins, jewelry, and relics in the Denver downtown area.

With the NO MOTION mode, one can hold the detector right over a target, ground cancel at the same time, and eliminate the top 2-1/2 inches of trash soil on top, and find coins even when in full pull tab rejection.
Melbeta

[Melbeta]

No one?

Everyone believes that baloney hype that the machine goes so deep, it picks up lots of trash?

Everyone believes that baloney hype that the machine does not go deep enough in discriminate?

No one has installed a LED on the BAD side of the meter as a modification? No one has made the modification that makes the meter GOOD/BAD more sensitive? No one has made any other modifications?

No one has made up the Body Mount board, removed the detector case, from the stem mount, attached the case to the tummy, and made a new body mount rod?

No one has removed the factory potted BLANKER MODULE, and replaced it with George Payne's 1" to 4" on/off bypass switch, adjustable depth blanker circuit?

No one believes these facts?
01_The Coin Magnum will still pick up small GOLD U.S. coins while in full pull tab discrimination! Will your detector
do that?
02_The Coin Magnum will still pick up U.S. Nickels deeper then 2-1/2 inches while in full pull tab mode! Will your
detector do that?
03_The Coin Magnum will still pick up most of the gold rings while in full pull tab mode! Will your detector do that?
04_The Coin Magnum will not detect surface trash in the first 2-1/2 inches of the surface area! While doing that
it will eliminate all surface trash, while still detecting good targets deeper then 2-1/2 inches. Will your
detector do that?
05_The Coin Magnum will identify GOOD/BAD targets with the meter in ALL MODES! Even in pull tab rejection. Will
your detector do that?
06_The Coin Magnum eliminates the ground mineral in both all metal mode and discriminate mode, and uses no
motion to discriminate! Will your detector do that?
07_The Coin Magnum has a mercury switch, that cuts out the audio when you lay it down to dig targets! Will
your detector do that?
08_The Coin Magnum will permit an audio amplifier circuit that will bring in faint deep small targets, so deep you
will not believe it!
09_The Coin Magnum uses either an Axial coil or a Concentric coil! It uses standard 8" and 12" coils!
10_The Coin Magnum has an optional small prospecting Axial coil as an accessory if you find one!
11_The Coin Magnum has an optional body mount rod, as an accessory, if you find one. You can attach the
detector case around your tummy and there is virtually no weight using the body mount rod.
12_Now there are many more features, but I will not mention them here right now.
Melbeta

[WM6]

Hi Melbeta

Does that Coin Magnum "full pull tab rejection", actually rejet

- any pull tab
- at any pull tab orientation and
- at any detection depth?

Or it is promo hype only, as with any other metal detector?

[Melbeta]

WM
IT was designed in America, for the American pull tabs, and I was a dealer for Compass from the early 1970s until Compass went out of business in the 1990s. It came out in 1979, and had been tested for 3 years prior to that, according to what I was told by Ron Mack. I have a personal letter from Ron Mack, telling me technical details of the Coin Magnum.

Remember, George Payne reverse engineered the Coin Magnum, and came up with his own Blanker circuit, which he patented in a Big Bud metal detector. It was impressive enough for George Payne to reverse engineer it.

Now I always tested the metal detectors, with three flat pull tabs, one fully ferrous, the second approx half ferrous and half non-ferrous, and the third all aluminum. I cannot give you a 100% answer, as that would not be correct, as when a pull tab is bent out of shape, the resonant frequency changes from the original resonant frequency. And in the case where the tail of a pull tab comes loose from the ring of the pull tab, again the resonant frequency changes. Even a ring, that has its ring shank cut, by a jeweler, has changed the normal resonant frequency of ANY ring. Any time a trash target, or any target's surface area is disturbed, it does affect and change the original resonant frequency, and thus the metal detector will respond to that target differently from a normal target. A normal target responds differently from a target that is at another angle in the ground!

And as you and I both know, as a trash target goes deeper into the ground, the resonant frequency also changes. Depth affect signal strength the deeper it goes. And orientation affects detection as well. A U.S. silver Morgan dollar was found with a detector showing it was a dime, and it was 14 inches down and standing vertically on edge. So the surface of a target, greatly affects any target as far as rejection and as far as identification goes.

Now you are in a foreign country, and of course, your coinage and your trash differs from U.S. coinage and trash, so you would really need to acquire one of the machines, and test it there. They were sold in England and in Germany and in Italy.

And as far as promo hype goes, I learned to ignore it and do my own tests. And of course, ground mineralization in the U.S. varies from state to state, and from town to town, and from place to place. So what I was stating was my own experience with the unit.

This is why, Compass in their Challenger machines, the Chief Engineer set up two categories of the Pull Tab, naming one as P.T. #1 and the other as P.T. #2. There are from my experience more then just two categories of Pull Tabs, but as I looked at schematics they were limited by the electronics they were using. As you probably know, the Coin Magnum did not use a TID meter for identification, it only used a Good/BAd meter. It was the first metal detector after George Payne's VLF invention tuning out ground minerals and it did full rejection of U.S. Pull Tabs while still finding the targets I mentioned, which was amazing!
Melbeta

[WM6]

Thanks for detailed explanation.
I never tried any Magnum brand, so not know much about Coin Magnum.
Agree that some old metal detector design are still competitive.
Recently I am impressed with CZ3D.

[dbanner]

Can someone please help me to identify this Compass Relic Magnum coil? https://www.youtube.com/watch?v=dT0v_YfTIbY
What type of coil configuration is this, double omega maybe? I don't know.

[Melbeta]

Dbanner,
I live in a secluded forest area, so I only have access to the internet through an old telephone line, using USB dial up modem. Thus I cannot obtain sufficient bandwidth to view anything on Youtube. If you can, post the photo of the coil here, so I can actually see the coil.

But I know the Relic Magnum product completely. You did not actually tell me the full Relic Magnum model number or name, but I know them from the first RM machine to the last RM machine. I can answer it accurately and completely. It has been answered below...

If it has a white coil, with black decal lettering, is an Axial coil, which they patented.

If it has a colored decal, it is a Concentric coil, which was the last coil they put on it before they quit selling the Relic Magnum models. The Concentric coil will go 1-1/2 to 2 inches deeper then the Axial coil. Whites Electronics made Omega coils. From your guess here, I am guessing it is the Axial coil you are describing.

Now if it is one of the small gold prospecting coils, it is an Axial, despite any markings or names on the coil.
Melbeta

[dbanner]

The video is titled relic magnum 7A

[Melbeta]

Dbanner
The description I gave you was for the RM7a model, as it was the most popular and the last of the RM series models. Your first photo is of the RM7a. Now the second photo, shows the inside of the stock coil, which I called an Axial coil, but Compass called it a Co-Planar coil. Now the reason I called it a Axial is due to the graphic which is in the patent. But as you look at the drawing graphic, you can see in one drawing it looks like an Axial, anther drawing it looks more like a co-planar coil, and in another drawing it kind of looks like a concentric coil.

Now as I have never seen the innards of the Axial coil, your photo could be it, and perhaps is a home made variation coil that someone make up inside the case of the Axial coil. I do not know for sure. Carl or Qiaozhi will have to wade in on this one It sure as heck looks more like the Nexus coil inside, doesn't it? I can only tell you what they made for the RM7a, not what any of the coils look like other then the concentric, which I have seen inside it... I guess flip a coin. Or buy it and see how it works for you.

The RM7a is a VLF for all metal mode, but the discrimination is not VLF motion unit, but a TR discriminator. Which is why the Coin Magnum, which came out the same time of the RM7a is VLF and VLF Disc.

Here is the Abstract description:
A unitary balanced-inductor system for use in the search head of an electronic metal detector, having a transmit coil, a smaller, preferably concentric cancel coil of opposite polarity, and a yet smaller receive coil inductively decoupled from the combined transmit and cancel coils. The cancel coil preferably has a smaller number of turns and is located in a slightly higher plane than is the transmit coil, while the receive coil may be placed in a slightly lower plane than the transmit coil, to provide adequate sensitivity to the presence of conductive or magnetic objects separated from the search head without unacceptably high sensitivity to similar objects relatively close to the search head. A closed loop load coil located between portions of the transmit coil and the cancel coil may be used to provide an inductive load on the transmit coil thereby further reducing the sensitivity of the search head to targets in close proximity to the load coil. The graphic drawing of the coil follows as an photo...

Melbeta

[dbanner]

Well that's very interesting. I did read the patent with the axial coil layout photo you posted. I was expecting to see such a layout inside the coil in video of relic magnum 7A, but was a little surprised to see what appears to be twin TX cancel coils instead of single concentric cancel coil. The RX coil looks as it is described in diagram. This is likely a variation on the axial coil layout in patent. It's the only coil I've seen made up like this. I also notice trimmers(presets) on coil pcb, no doubt for inductive balancing.
I sure would like to see a schematic of coil circuit for this one(including small pcb). Looks very unique indeed.

[dbanner]

Small correction, the trimmers on small board are not for "inductive balancing" as I previously stated. But for fine balancing (nulling).

[Melbeta]

Well that's very interesting. I did read the patent with the axial coil layout photo you posted. I was expecting to see such a layout inside the coil in video of relic magnum 7A, but was a little surprised to see what appears to be twin TX cancel coils instead of single concentric cancel coil. The RX coil looks as it is described in diagram. This is likely a variation on the axial coil layout in patent. It's the only coil I've seen made up like this. I also notice trimmers(presets) on coil pcb, no doubt for inductive balancing.
I sure would like to see a schematic of coil circuit for this one(including small pcb). Looks very unique indeed.

I can make a good guess. When Compass was testing their detectors, they made up different main boards, sent them out to service centers, who tested them, switched out to another board, tested that one, and so on. I imagine they also tested various kinds of coils as well.

The inside fine tune board, was a common board, they differed slightly in different kinds of coils, was used to set the nulling I believe. Compass was very innovative company. They had a smaller service center in a dealers shop in Pennsylvania, and he switched out and tested many board variations. As I understand it, the DD coil they built went the deepest, then the Concentric coil, and the last was that Axial coil.

But the gold prospecting smaller coils, all were of that Axial kind, and they were pretty hot coils. They had to be set up on the detector, by some internal adjustments.
Melbeta

[dbanner]

Some day I hope to experiment with this type of coil design. Thanks again for tremendous information. One more thing, I found a schematic that purports to be the RELIC MAGNUM 6. From your knowledge, was this a reasonably good detector, similar to the 7A in performance?

[Melbeta]

There were differences between early to late RM6 models..........

Some day I hope to experiment with this type of coil design. Thanks again for tremendous information. One more thing, I found a schematic that purports to be the RELIC MAGNUM 6. From your knowledge, was this a reasonably good detector, similar to the 7A in performance?

Early RM6 had smaller meter, later RM6 had larger better meter. Some RM6 did not have the coil coax connectors, were hard wired to the motherboard. If I ordered two coils, then each coil had its own connector and could be removed and switched. Other then that, it is standard RM6 machine. It has what it has.

RM6 is smaller brother to larger RM7a (a=automatic) model. It was reasonably good but RM7a was far superior. Compass used the RM6 and the RM7A to check out various board changes for the Coin Magnum final unit. They ran the field tests for 3 years I believe I was told. You might end up with such of those machines. I have no way of knowing the test units.

I have all of Compass schematics on up and through the Challenger X-100, then beyond it my schematics are hit and miss. But before it I got most of them. Probably not all model versions of course, but have some of them. If you are trying to gain some experience, do what I did, bought them, tested them myself, then decided if I liked a model. If I liked a model, I sold them. If I did not like a model, I could not sell them. That is how I am, just like with food, it has to pass my test first before I eat a second meal. I tell it the way it is. No fake stories from me.

I still have a near brand new RM6 stored, for some reason it does not work now, so someday will have to go into it and fix what is wrong, and it will be somewhere from Power Supply and beyond.
Melbeta

[dbanner]

Thank you so much for answer. This is greatly appreciated. Your answers are comprehensive and honest. You are good person to emulate. I have learned a whole lot about the way you answer questions.
I like the older metal detectors. They are a work of art as much as they are electronic devices. Fascinating! Thanks again.