Sniffer XR-71

[bmwbiker]

Just tried to post a reply and for some reason it wouldn't . . .

Really pleased that it works for you - if the lumps of gold aren't there you won't find them Yes, it's going to take you a while to get used to the machine so you'll just have to take your time.

I wrote to the Bulgarian guy to ask for details of the coil - inductance, resistance etc and I've wound a simple mono coil within his parameters. Later, if it works OK on that, I'll wind a faster basket-weave coil to see how that works - it will only cost me for the wire and I've already made the former for it and proved it with twine just to find the length. It only took about 30 minutes to wind it. I also asked him about shielding and he said no need so I'll go with that.

Got a bit of a result this week when we got permission to detect on a large-ish local farm which is also host to an annual show. Should be fun!

Great result on the detector - YOU built it and IT WORKS - never forget that! Good luck on your farm land - one of the ones we detect on is riddled with iron . . .

Clive

[ZX12R]

Ok, done some detecting today in the rain on farmland.
found 2 horseshoes, 3 iron bars, 1 lump of lead, several square headed bolts and 13 golf balls, the land is next to a golf course, all this is 1 corner of one of the fields.

The fields are on a slope and there is lots of water.

I kept my box covered with some plastic but the wind kept blowing it and the only thing is that when I get a signal I have to either squat very carefully or take of the box (its on a strap around my neck) and place this on the ground, I might try and make it hip mounted.

clive you will love it when you get yours working, it picks up very small items when the spare one (viking vk30) misses them so I have been using mine as a source to find objects then the VK30 to act as a pinpointer :-)

Jason

[bmwbiker]

I'd no idea that golf balls could be detected by any kind of metal detector . . . Since I'm left-handed (and skint . . . ) I've never ben interested in golf, so the last ones I saw was when I was about 10 (VERY long time ago) IIRC there was a plastic skin, about 200 miles of elastic band-type material and a sac of some kind of liquid rubber that squirted in your eye when you tried to hacksaw one apart (ask me how I know . . . ) They must have changed in the intervening half century

Sounds like you're going to have some fun with that Sniffer of yours - I've been told that PI machines do love iron though. I'm fortunate that the Minelab has a very good pinpointing feature on it, although the small item aspect sounds good. I'm planning on keeping mine for beach detecting when I get it finished.

I'm building mine more like a conventional detector but with the PCB underslung in a box and the controls in another box on top of the handle. I hooked it up temporarily today just to make sure it's going to work (it does - kind of . . . ) before I commit too much more time and effort. I switched it on in the kitchen/dining room so it was surrounded by all kinds of steel appliances and fluorescent lights and my PC, and I'm not convinced that the coil is right, but it does beep when metal gets close enough. Maybe there was just too much metal and noise about and it was overloaded?

What sort of range were you getting in your metal-filled dining room?

Clive

[ZX12R]

Ha-Ha, the golf balls were just laying in the field so I just picked them up.
My dining room is quite full of metal but it would easily detect my motorbike when the coil was about 4-5 feet away from it, maybe even 6 foot (I have just laid down on the floor with my feet touching the bike and the coil was roughly where my head was - I am 6 foot).

I think the we will be staying local for a while as I have been out now about 3 times with it and feel that the battery must be getting low now (dont have a charger yet) so I dont want to go all the way t beach again, turn it on and the red battery light is on.
I might put a better quality headphone socket in it, one that wont bend out of shape when I insert the phone jack.

[bmwbiker]

OK, you got me this time - serves me right for teasing you about the Hoard Of Halifax. Well, how was I to know that they're not putting metal in golf balls these days . . ?

I bought one of those bendy headphone sockets for the Barracuda to begin with but replaced it before I started with a 1/4" stereo one from Maplin (Part No BW79L.) Much more robust. I could have got one off eBay but it would have been no cheaper and I just happened to be near a Maplin store one day. I just wired the two channels together so both sides of the headset worked.

Sounds like I need to make another coil for the Sniffer. I originally made it to Stilliyan's spec - 30 turns on a 280mm former, using 0.5mm wire. When I wrote to him to ask for the specifications he said it was 800 uH max; mine was showing 1300 uH on the meter so I removed about 5 or 6 turns until it got below 800. Maybe I should have tried it as it was first . . . ? I've got some new wire on order so I'll have a go when it arrives.

Do you have an Oxford battery charger for the bike? Since they're intelligent they adapt to the battery's requirements so *shouldn't* do any harm on a temporary basis. If you've ever metered the voltage out of some mains adaptors (wall-wart type) there are huge discrepancies with what is stated on the rating labels so I figure a dedicated battery charger should be better. I use an old Zig unit charger out of a caravan to charge lead acid batteries since it's designed to be charging the leisure battery day in, day out.

We're not doing much on the fields at the moment - it's too easy to make a lot of mess and the detectors get covered in mud, plus the soil is waterlogged and a shovelful weighs a ton. That's why I'm trying to get some beach detectors going - especially since we had a good bit of wind lately. And the wife and I are going to Scotland for Christmas - within 15 mins of a beach at Girvan . . .

Never mind, if all else fails I can take the Minelab for me and the Viking for her!

[ZX12R]

Hi Clive,
How's it going with the build.
I have been out with mine a few times now it seems to love finding horse shoes, ha-ha
If the weather is dry on Sunday I might be going to Blackpool for about 7am-8am, I think that the tide is low then, that's if the car is ok, the battery died a few days ago so been trying to revive that, I'll let you know if I find anything.

Just started getting into radio controlled helicopters as well and been doing our lasses 125 for MOT etc.
Oh and I have built her a surf PI as well

Jason

[bmwbiker]

Hi Jason,

Been meaning to get in touch but life keeps getting in the way - never been so busy!

Well, I hooked all the pots up and made a quick-and-dirty coil and it kind of beeped when I put metal near it, but I was having trouble adjusting the threshold. Anyway, I'm now at the stage where I've got the PCB housing mounted to the shaft, the PCB inside it and a battery box slung under the PCB housing. The control box is a separate module mounted on top of the handle, like my Minelab, and I've got most of the electronics hooked up - I'm having to do it in 'layers' cos there are places where the fuse, headphone socket etc overlay the pots.

Trying to make a professional-looking job on it, I was going to acid-etch a panel overlay with the control legends, but accidentally put a sheet of inkjet photo paper into my laser printer, which welded itself to the drum and FUBAR-ed the cartridge, as well as sending the printer haywire. I've also wound a basket-weave coil (see the 'Coils' section in this site) to the same parameters Stillyan gave me as well as a bog-standard mono 30-turn 28 cm one.

Then life got in the way again and I needed to do some other stuff so the Sniffer is on a back burner for a little while. I was due for a change from it anyway - it's like I was eating, sleeping and breathing metal detectors. Building a book scanner as a matter of urgency right now so I can return some books to their rightful owners next weekend.

Went out with the Minelab on Monday and Tuesday, to the beach at Talacre (10 minutes from here) and Rhyl (20 minutes) but it hates wet sand. Since it has auto-tune I can't tune the salt out either. Talacre is known for being a trashy beach anyway, but I kept getting signals which would sound off then disappear. Wasn't just me - my buddy was getting the same thing. At one stage I had a good consistent signal which stayed, but as I dug it disappeared again. I went over the stuff I'd dug out and found a short section of a thick reed-looking thing with a burnt end . . .

My battery went just after Christmas - bought a heftier one from a company called Tayna in Abergele - they also sell on eBay with free delivery. 75Ah battery for our Polo diesel for £45 on eBay (but £37 cos I could collect . . . ) 4-year guarantee, same battery in Halfords £75 . . .

'Oh and I have built her a surf PI as well . . . ' You can't just say that and leave it - explanations are required.

Good luck on the beach if you get there - if I had a PI working I'd run over and join you!

All the best,

Clive