Vallon VMH3CS Mine Detector

[Mdtoday]

Hi Eric,
If it's not too much trouble, could you post some pics of the 7 pin connectors please.
They look suspiciously like Conxall Mil-E QUAL series connectors with custom over mold.

Brian

[Ferric Toes]

Eric; Thanks for the Vallon manual link. Here I show an adapter for a White’s lower rod to the Vallon VMH3CS. It is made from two common home improvement store plumbing items, and requires some lathe work. There may be a 7 pin connector that could be potted in, but one could probably just use pins and wires, sealed out to a small external connector. Not ordinarily opening that joint again (by changing coils at the coil end). I used a threading die to cut a 1.5-8tpi thread on the adapter’s existing OD, though threading in a lathe would make maintaining axial alignment easier. Also, the ID on that end has to be opened up to 1.215”. The other part is a sawed off and faced pipe nipple with the existing hole drilled out to .75”. There is plenty of opportunity for further refinement.

Hi Th'r,
That is a good way of doing it and using the existing thread on the middle rod. Now you have identified the thread, I will look into that further.

My way is perhaps a bit more drastic and also requires lathe work. First is to cut off the existing connector housing and locking collar. You might think that undoing the three screws would achieve this, but the screws seem to have Threadlock applied and even if you do get them out, the body is cemented to the shaft with epoxy. Be careful not to cut through the coax. Undo the locking ring securing the hard rubber connector body in the now free outer housing. Pull the plug forward and then cut longitudinal slots in the housing to free the cable.

I can't remember the exact stages from then on, but the picture paints a thousand words. At least it shows that various parts involved and the potential to use alternative home built coils. In this instance the yellow tube contains a ferrite cored probe. The correct size pins are readily available and I plug the live one into the middle female socket and the ground one into any of the outer six. When coupled together, the pins just retract into the internal space in the yellow tube, which could alternatively be a Whites lower shaft.

The inline connector is normally on the end of the coax, but I cut it off so that I could pull the whole cable from off the bulkhead but leaving enough to rejoin later. The red and blue wires are from the battery supply. All the latter is only necessary for a full dismantling. The connector plugs into the distribution board, which is the first thing you see when opening the main box.

Oh yes, the pipe fittings are George Fischer pvc and available from RS Components. Heavy duty and O ring seal. Pvc parts are secure to the fibreglass tubing with Double Bubble epoxy resin, Pvc needs to be roughed up with sandpaper to give good adhesion.

All the above by Th'r and myself are just suggestions and ideas, and requires a certain level of mechanical expertise and use of a lathe. Refinement is ongoing and it is better to wait until full instructions emerge before attempting changes that may be irreversible.

Eric.

[Qiaozhi]

Hi to Brian and Th'r,
You don't actually need 7 pins; 2 will do . Vallon use 7 pins to make a psuedo coax connection, i.e. the middle pin is live and all the outer ones are connected together to coax ground. I suspect that this is an emi precaution, but not relevant in civilian use. I have a 'rejected' coil and shaft where one outer pin has broken off. It works perfectly.

Eric.

Presumably Vallon make this pseudo coax connection in the plug because the housing is plastic. With metal connectors (such as those used by Whites Electronics and Minelab) I always add a bare wire from the coax to the metal housing of the plug. This allows the metal case to act as a shield. Otherwise I've noticed that touching the outside of the plug can sometimes produce a signal. This is a bit odd because you would think that the metal case of the plug would already be electrically connected to the metal socket.

[Mdtoday]

Hi Eric,

Thanks for the info, I have access to a large range of different multi-pin circular connectors here in Oz at reasonable prices too so should be able to find a fit for purpose one.
You have done excellent work on the Vallon, so I thank you for that. It certainly got my attention when I started seeing them appear on the surplus market.
I'm looking forward to constructing a few different coils and mounting methods and taking the unit out to the goldfields to see how it performs.
I do own a couple of CNC mills and flatbed routers that have been pressed into service to make coil housing molds, brackets and other electronic housings etc.
Now seeing your work it has inspired me to be a bit creative and see what I can do with one of these beasts too.
I don't think my package will arrive for 2-3 weeks but I'm a patient man
In the meantime might see If there is any technical/ dimensional drawings around.

[Ferric Toes]

Hi to Brian and Th'r,
You don't actually need 7 pins; 2 will do . Vallon use 7 pins to make a psuedo coax connection, i.e. the middle pin is live and all the outer ones are connected together to coax ground. I suspect that this is an emi precaution, but not relevant in civilian use. I have a 'rejected' coil and shaft where one outer pin has broken off. It works perfectly.

Eric.

[TH'r]

Eric; Thanks for the Vallon manual link. Here I show an adapter for a White’s lower rod to the Vallon VMH3CS. It is made from two common home improvement store plumbing items, and requires some lathe work. There may be a 7 pin connector that could be potted in, but one could probably just use pins and wires, sealed out to a small external connector. Not ordinarily opening that joint again (by changing coils at the coil end). I used a threading die to cut a 1.5-8tpi thread on the adapter’s existing OD, though threading in a lathe would make maintaining axial alignment easier. Also, the ID on that end has to be opened up to 1.215”. The other part is a sawed off and faced pipe nipple with the existing hole drilled out to .75”. There is plenty of opportunity for further refinement.

[Mdtoday]

Hi jj,
Hope you enjoy the Vallon. It is a good detector and is well suited to detect coins, rings and gold nuggets.

If you go back a couple of pages, there is info on the coils I have recently built and work successfully. You need to get the inductance close to 1.5mH; resistance to approx 4 ohms including cable; and resonant frequency 140 - 170 kHz. All these whatever size coil you make, then it stands a good chance of working. The coil must be shielded otherwise you will be sounding off on wet grass, sea weed, and of course wet ground and wet sand on the beach.

You asked about connectors. Presumably the one you are interested in, is the 7pin one in the shaft coupling for the coil. I have not found anything suitable as yet and think that one was a special, designed by Vallon, also there would be a problem finding the mechanical coupling that it would fit into. All my, coils bar one, have been made for electronic units that I have rehoused.

Eric.

Hi Eric,

I'm about to purchase one of the VMH3CS units from UK EBAY but did have a question for you.
Does it look possible to replace the 7 pin connectors in the housing?
Is it soldered onto PCB or wire tailed?
I am interested in making some different coils and swapping out the the connectors to more available types.

Brian

[Ferric Toes]

Hi Eric
Is there a formula for calculating the number of turns to the size off coil cheers.

jim

Hi Jim,
If you go to the 'Coils' thread, at the top you will find a 'Coils Calculator' which is a sticky post i.e. it stays there at the top. Try that.

Eric.

[roadhog]

Hi Eric
Is there a formula for calculating the number of turns to the size off coil cheers.

jim

[Ferric Toes]

hello everyone ,

Eric , For shielding, I use scotch 24 but Do you think if the roll tape electrically conductive ,w12 mm;l33;d:0.078mm;60%
Will be effective
i see on ebay
http://www.ebay.fr/itm/1-roll-Tape-electrically-conductive-W-12mm-L-33m-D-0-078mm-6-/172490284953?hash=item282938df99:g:BccAAOSwjDZYfju A


Thank you for all your advice

Regards
Fred

I can't actually see what the tape is made of. Is it copper, nickel, aluminium or some other? woven or solid?

Eric.

[roadhog]

Thanks For the info Eric thats grate. As for the connector it looks like i may have to try and 3d print them .

Ill let you all Know how i get on.

[tifred]

hello everyone ,

Eric , For shielding, I use scotch 24 but Do you think if the roll tape electrically conductive ,w12 mm;l33;d:0.078mm;60%
Will be effective
i see on ebay
http://www.ebay.fr/itm/1-roll-Tape-electrically-conductive-W-12mm-L-33m-D-0-078mm-6-/172490284953?hash=item282938df99:g:BccAAOSwjDZYfju A


Thank you for all your advice

Regards
Fred

[Ferric Toes]

Hi All
Just got a vallon VMH3CS for £180 here in the uk. was wondering if anyone had manage to flash the unit, or has a good step by step guide on building small/large coils for this unit?

allso has anyone manage to locate a place to get the connectors used.

cheers jj

Hi jj,
Hope you enjoy the Vallon. It is a good detector and is well suited to detect coins, rings and gold nuggets.

If you go back a couple of pages, there is info on the coils I have recently built and work successfully. You need to get the inductance close to 1.5mH; resistance to approx 4 ohms including cable; and resonant frequency 140 - 170 kHz. All these whatever size coil you make, then it stands a good chance of working. The coil must be shielded otherwise you will be sounding off on wet grass, sea weed, and of course wet ground and wet sand on the beach.

You asked about connectors. Presumably the one you are interested in, is the 7pin one in the shaft coupling for the coil. I have not found anything suitable as yet and think that one was a special, designed by Vallon, also there would be a problem finding the mechanical coupling that it would fit into. All my, coils bar one, have been made for electronic units that I have rehoused.

Eric.

[greylourie]

That download location was "last modified" on the 11th of April. And the Veva2000 software is still available to download. Wonder what use could be found for that in the civilian aftermarket ? Archaeological mapping ?

[kingswood]

You can now download the full operations manual for the Vallon VMH3CS in English from their website. It is the 2007 version which seems the same as the 2009 - 2010 detectors that are on the surplus market.

Eric.

http://www.vallon.de/pdf/download/Vertrieb/GB_VMH3cs_oper_manual_soft_1_14.pdf

Thats quite nice of Vallon I guess they thought that was the easier way rather than having new users constantly emailing them