Vallon VMH3CS Mine Detector

[Ferric Toes]

I recalled that someone once told me FTP had a Vallon, so I poked around the dustbin and found it. It's a VMH3 without the CS, which apparently means Changeable Searchcoil, because that appears to be the only difference.

A couple of years ago I picked up a copy of Janes Mines and Mine Clearance 2009 - 2010, at a swap meet. It has a section covering the various countries and the mine detectors they manufacture; Vallon being one for Germany. The VMH3 details are there and from the pictures it appears that the seach coil is not changeable, whereas the VMH3CS has this facility. On the following page is the VMH3S which has interchangeable coils as does the VMM3 on the next page. Whether CS really means changeable search coils, one can't be sure.
One difference between the VMH3CS that I have is a push button for pinpointing which is absent from the VMH3 picture in Jane's. The button with the crosshairs appears to speed up the 'retune' and sharpen the response. The other variable is that the firmware can be reprogrammed on all machines for different applications, which presumable would affect the small object response and range.
I will check the 'air' range on a US Nickel and see what I get.

[Ferric Toes]

Metal enclosure is good for emi but no good for capacitance between mosfet / ground PCB / ground enclosure and metal heatsink.

I recommend using a metal box and use a ceramic sink for the capacitance ! You'll see all your problems disappear! heat dissipation, emi, capacitance etc ...

Alexandre

Alexandre, This thread was specifically started to discuss the Vallon VMH series of mine detectors. Would it not be better to have a separate thread for your interesting, but non-related, material?

[Asgard]

Alexandre, This thread was specifically started to discuss the Vallon VMH series of mine detectors. Would it not be better to have a separate thread for your interesting, but non-related, material?

Maybe but I'm not doing it now that it is written.

[Qiaozhi]

Alexandre, This thread was specifically started to discuss the Vallon VMH series of mine detectors. Would it not be better to have a separate thread for your interesting, but non-related, material?

Maybe but I'm not doing it now that it is written.

I've moved all posts related to the Manta Metal Detector here -> http://www.geotech1.com/forums/showt...Metal-Detector

[Ferric Toes]

I will check the 'air' range on a US Nickel and see what I get.

I checked a US nickel on my VHM3CS and get an air range of 15 inches for a definite response and 16 inches for an iffy response that you would likely miss. I think that is good for a coil which is about equivalent to an 8 inch diameter. That is why I want to make a 12in and see what I get then. What foil are you using, Carl? Is it baking foil?
I hope to get another VHM3CS shortly, which I will be happy to open up and look at the works.

[Ferric Toes]

I forgot to mention that with the detector ground balanced on a 0.5lb (0.227kg) lump of Australian ironstone I appeared to have lost 2in in range for the nickel.

[mickstv]

I Eric, just wondering if you could post some pictures of the response to your ironstone target at 1v and 100mv scales.

Thanks
Mick

Eric, did you have a chance to take some CRO shots of what happens to the TX current and RX with ironstone targets ?

[Geo]

Yes, the unit is complete with the carry case, manual, field card, and firing pin OTP (operational test piece). This unit does not appear to be as good as yours. At max sensitivity it will detect the OTP (which tells me it's working within spec) but a US nickel is only 9-10" or so, and it won't detect my 1x foil standard at all. The TDI easily beats this.

I think there is something out-of-whack on this unit. My foil standards are square 1"x1" pieces of foil layered in clear packing tape, with 1x being single layer, 2x has 2 layers, etc. I have 1x-8x continuous (helps identify target holes), plus 12, 16, 24, and 32x. The 1x is invisible. 2x has a negative response, that is, I get a signal as the target moves away from the coil. 3x has a weaker negative response, 4x a decent positive response and the rest look good from there. I'll try to play with it some more today.

Yeah, the Recon/ATX looks a lot like the Vallon. I also have an ATX so maybe I'll try it as well.

Carl, do you remember at witch distance the TDI detects a US nickel with GB= On???

[Geo]

I checked a US nickel on my VHM3CS and get an air range of 15 inches for a definite response and 16 inches for an iffy response that you would likely miss. I think that is good for a coil which is about equivalent to an 8 inch diameter. That is why I want to make a 12in and see what I get then. What foil are you using, Carl? Is it baking foil?
I hope to get another VHM3CS shortly, which I will be happy to open up and look at the works.

Eric, how is the responce of VHM3CS at biger objects like a soda can, compared with other detectors as your GS5 or TDI???

Regards

[Ferric Toes]

Eric, did you have a chance to take some CRO shots of what happens to the TX current and RX with ironstone targets ?

Not yet. The signal is not enough to show as the preamp I used so far only has a gain of x10. I need to increase it to x470 (53db) which is what I normally use.

[mickstv]

Thanks Eric.

[Carl-NC]

Whether CS really means changeable search coils, one can't be sure.

Yeah that was just a wild guess.

One difference between the VMH3CS that I have is a push button for pinpointing [ATTACH]36197[/ATTACH] which is absent from the VMH3 picture in Jane's.

Mine has the exact same layout, including the pinpoint feature.

What foil are you using, Carl? Is it baking foil?

Yes, I figured that's probably pretty consistent no matter where you are.

Carl, do you remember at witch distance the TDI detects a US nickel with GB= On???

Typically 11-12" as I recall.

With the Vallon at max sensitivity, it would not detect my 1 gram nugget. Right now I don't have time to dig into it any more, at some point I want to open it up and see what's going on. As I said, something doesn't seem right.

[ivconic]

...at some point I want to open it up and see what's going on. As I said, something doesn't seem right.

Feel free to take macro shots from inside and please do share here.
Such huge intrigue grows here, so it would be interesting to see what is all about.
Most certainly there is decent uPC inside, controlling all the things.
Yet analogue part would be very interesting to analyze.

[Asgard]

Hello Carl, Eric,

I do not understand, you work together officially on new technologies for fisher lab (research) ? or Eric still working for white's ? Or Eric you're retired ?

Alexandre

[Carl-NC]

Hello Carl, Eric,

I do not understand, you work together officially on new technologies for fisher lab (research) ? or Eric still working for white's ? Or Eric you're retired ?

Alexandre

I work for Fisher (First Texas), Eric is retired. Previously we did some work together when I was at White's.