Vallon VMH3CS Mine Detector

[greylourie]

Maybe the picture in Janes of the VMH3 is of an earlier version. Because a look at images in the respective pdf brochures on their website for both models, shows them sharing identical buttons and knobs. Vallon also has evaluation software available for download, so with the right cable it should be possible to log the output of the detector to a computer/laptop. (http://www.vallon.us/download/download.html)

[Ferric Toes]

More features on the VMH3CS

This detector has more features than I thought. When you switch on there is first a self check, after which it defaults to a standard high sensitivity mode with no compensation. By pressing the + button and holding down the sensitivity level is indicated by the number of LEDs illuminated with the default at 12. If you keep holding the button down it goes up to 13 and finally 14. Sensitivity is reduced in the same way by pressing the - button and can be brought down to level 1. Any changes that are made when the detector is switched on, are cancelled when switched off and the default setting of 12 returns.

The operation of the pinpoint mode is different to what I previously thought. When the button with the crosswires is held down the detector changes to a non-motion mode. This means that the signal does not disappear when the coil is stationary over the target and the maximum signal is more easily heard to give best pinpointing.

Various combination of the buttons can bring up different features. There is a surf mode for using the detector in sea water. This, I guess, retards the sampling a bit to reduce the effect of sea water conductivity. I will check this out when I go to our local beach shortly. Apparently this setting is stored when unit turned off, until reset, and may account for the lower range on a nickel that Carl was getting on his unit. The pinpoint button and - have to be pressed together for surf operation. Pinpoint button and + for land. For compensation in water, the C button is pressed, then released, with the head in water and prior to searching.

There is what is called 'channel adjustment' this is to eliminate outside interference and crosstalk with other detectors. This is done with a combination of buttons and the unit switched to speaker mode. Channel settings are stored until changed.

There are 6 filter settings with different bandwidths to decrease the effects of electromagnetic interference. Default is 6Hz and minimum bandwith 0.5Hz. This has yet to be investigated, and how this affects performance. Filter settings are not stored at power down and return to default of 6Hz.

More later on the ground compensation facility.

[Asgard]

Thank you for your reply Carl, good progress on your projects do not hesitate to come to me, if you have needs, I would be happy to help you.

[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.

[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

[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.

[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.

[mickstv]

Thanks Eric.

[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.

[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

[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???

[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 ?

[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.

[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.

[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