Vallon VMH3CS Mine Detector

[green]

Hi godigit
Regular strength aluminum foil TC is about .07us/mm for a square. HD is about .1us/mm for a square. Width pretty much controls the TC, best to keep test piece square since length has some effect.

[godigit1]

Ok I've had time to make it further along in the thread.
I see now i made the same mistake as Phiphi in his first evaluation of the Tx.
Vmhc1 is the same as the Vmh3cs Tx.

I'm too page 26 of this thread so far time is limited but at this point no one is detecting the 1 inch square of foil.

The Vmh1 is not advertised as uxo capable I'm not sure if that is due to coil change ability or of a different processing algorithm maybe?

in the manual for the vmhc1 it says it detects all metals and even mentions gold. it also says it is the first detector specifically for special ops.

First I'm not sure the foil type others have used but with reynolds wrap heavy duty freezer foil the vmc1 hits it at 4 inches with the sensitivity turned down to 10 best I can get in my house..
3/4 by 1 inch it does not detect.

Also have noticed with the Vmc1 that the vibration alert is more reactive on the smallest targets. (Most sensitive.)

Still reading this thread but think I'm going to make a dual field coil to try on the vallon.
Has anyone tried that Yet on a vallon?

[godigit1]

Hi godigit,
what are you connecting your scope to, to measure the above waveforms? I know that if I use a series resistor of 0.1 ohms to measure the current waveform, I get ringing at the beginning and end if I use a wirewound resistor, due to the small inductance it has.
To get a clean waveform, I use a thick film resistor. It is odd that the two waveforms are not identical in shape.

Eric.

Hi Eric,

I was using my probe at 6 inches from edge of the coil.

Today I was finally able to get the cap off the coil and attach the probe directly.
I measured the coil at 1.54 mH and 3.1 ohms but that was attached so not sure about the resistance.
I measured SRF at 1.38 Khz.
It looks like the coil specs are in line with the VMh3 coils.
So should be able to make a smaller coil for it.

Here is the Tx directly attached.




Compared to the Vmh3 the Vmc1 is quite a bit different as far as the Tx ,10 us pulses versus 50 us and 40 us between pulses versus 500
I'm still not sure if the different pulse forms are correct or if there is a problem with the gizmo.
It seems to works very well. have allot more to test and learn but have not found any functionality problems with it yet .
l
If anyone one out there has a Vmc1 and a scope please post the Tx here if you can ?

Thanks Again for all your work and support on the Vmh3.
Be Well

Sorry everyone about my last post I should have re-read it better. I was heading out the door for work.
It should be a (1.2 gram nugget at 6 inches )and (or a young ladies ring).

[Ferric Toes]

Hi godigit,
what are you connecting your scope to, to measure the above waveforms? I know that if I use a series resistor of 0.1 ohms to measure the current waveform, I get ringing at the beginning and end if I use a wirewound resistor, due to the small inductance it has.
To get a clean waveform, I use a thick film resistor. It is odd that the two waveforms are not identical in shape.

Eric.

[6666]

Hi GD, please let us know how it goes as I'm interested thanks.

[godigit1]

HI ,
I know this thread is about the VMHS3 and sorry for posting about the gizmo here but this seems to be the source for vallon info. I thought the 3 and one would be the same as the only difference in the ability is UXO due to the changing of the coils on the VMHS 3.

But looking at the Tx on the gizmo they are different.

Here is the tx,


the Pulses are only 8 us wide and still 528 us between pulses.

Im not sure if the ringing at turn on is my probe or the machine.

ringing



I tested the gizmo against my TDI pro on a nickel at 12 " and 1.2 at 6 gram Nugget on a hot rock strewn beach.
Both could get my targets but the gizmo could do it without being switched to mineral mode and Tdi had to be Ground balanced and backed off to 15us to avoid the hot rocks better.
I then hunted the vallon for a while its very deep and got gold first time out a small 14 k toe ring or your ladies ring weighing only 1 gram at 8 inches with a crisp clean signal.
If The V3 is better I have to have one and intend to pick up the first one I see.

Just wanted to share a positive comment on the gizmo and the wave forms so unless anyone is interested I will not dillute this thread any more.

Best Regards
Jim

[godigit1]

Just starting to study this thread better .
Eric thanks for all your work.
I picked up a vmc1 gizmo should be here monday.

Have you seen the specs on the new vmc4?
They say it will pick up low conductors like carbon fiber rods.
Wondering if this would be useful on tiny gold?
Just a thought.

https://www.vallon.de/en/metal-detectors/vmc4-ultra-compact-metal-detector

[jerry j]

Going to use the Vallon in Arizona to see how it does on gold.Their is some hot ground here I'm going to test it on.

[Ferric Toes]

Just picked-up a Vallon VMH3CS on Ebay $360 US

Let us know how you get on with the Vallon. Are you going to use it on the beach, or inland. Maybe both?

Eric.

[jerry j]

Just picked-up a Vallon VMH3CS on Ebay $360 US

[gravelmonkey]

I recently had to do the battery tube disassembly to add a screw to the armrest ( to prevent it from sliding ).
The procedure on how to do this is excellently described by Eric in this document:

[ATTACH]51114[/ATTACH]

For step 3, to prevent damage to the threaded collar, I used a so called strap wrench.
I acquired this recently to do some threaded PVC pipe plumbing.
Just wanted to mention this because it worked perfectly.
Before this, I had never even heard of a strap wrench, so here are some pictures:

[ATTACH]51115[/ATTACH]


[ATTACH]51116[/ATTACH]

My apologies if this has been posted here already.
The 2 "wings" at the bottom of my detector are a detector stand to keep it upright and it is made from part of the bottom piece of the Garrett arm rest that I used to replace the original broken ears.

Great tools, I have a couple I bought to undo the locking collar on the middle of the shaft after it jammed (I posted this problem a year or so ago).

[brinbrin]

Oooooh definitely what I need. I'll PM you.

[Ferric Toes]

Hello to all VHM3CS enthusiasts. Long time no post.

Two days ago, I succeeded in breaking the pin which prevent the upper telescopic shaft to rotate. Yes, I did it ! This detector survived
Did any of you experience the same problem ? Do I really have to dismantle the whole machine, or is there a simpler way to solve the issue ?

Best regards.

Brinbrin

Hi brinbrin,
At last I find that I can answer on the Forum. I found that my reply contained 'auto-saved content' with pages and pages of data which locked up my system. I could not upload any pictures and it seemed to slow the whole Forum down to a snails pace. OK on everything else. This is why I have gone back to an earlier post of yours to test if it is working properly.
Attached is a picture of a spare telescopic shaft I have available. They are impossible to separate, so you will have to change the whole thing. This one is in very good condition and comes with the T shaped pin to stop it rotating in the main box. In one of the detectors I bought, the inner shaft was jammed solid and the groove was cracked. The user had tried to rotate the shaft to free it, which sheared the T piece and cracked the inner groove, similar to yours. This inner shaft must never be rotated if it sticks. To prevent sand and water getting into the shaft, block the drain hole in the molding just below the battery cap. Wash the detector down after use, particularly where the shafts telescope.
PM me if interested in the shaft. I have your PM, thank you.

Eric.

[brinbrin]

Hello, Mr Foster.
I guess the pin I need is the flat one located under the body and fastened by one of the three black bolts. I put a blue arrow on the picture.
As for the crack, see by yourself on the picture (red arrows). This part is fibreglass and I can't see how this crack can have opened itself.
Best regards,
MC

https://i.servimg.com/u/f50/19/87/95/25/wp_20211.jpg

[Ferric Toes]

There is an image of the pin on post #1388 by Mr Foster. After a loser inspection, the top part of the telescopic stem is completely sanded out and shows a longitudinal crack. the seal ring is worn out. Not good. *** If anyone has spare parts (or even a whole dead machine), please make an offer. *** Can't believe I totalled this machine that had survived years of battlefield Looks like the sand on the beach of Boulogne-sur-Mer is harsher than Iraq's or Afghanistan's...I got it used, not in pristine condition, but way better than it looks now. BTW, for those who are interested, there are VMC1 for sale on ebay , but US only.

I have quite a selection of mechanical parts for the VMH3CS but need to be clear on what you need. There is a metal pin in the housing for the male plug on the lower shaft to stop it rotating, but you mentioned the top part. This is prevented from rotating by a flat plastic part held by one of the bolts on the underside of the main housing. You mention a longitudinal crack. What is that in? The shaft? Is the seal ring the slotted tapered ring that grips the shaft when you tighten the collar? If you can photo the damaged or broken parts on your detector and attach them to a post, I will see what I have that may help. Eric.