Surf Pi Professional Pcb's back in stock - NEW Prices

[der_fisherman]

Hi Andy
We are on similar wave lenths because your typical surf/bara and many more, the way they stand are only good for certain types and size of metals depending on how these lads have set up the specification ie coil,pulse width,p/ps, frequency, not going any further into that because theres been plenty discussed on the subject on this thread and many others.
Im a good reader and reading between the lines its possible to alter PIs to detect different type metals the problem lies in been able to walk a beach or field in one swoop and detect all types.
There about but theres alot more involved and alot on here would come unstuck constructing them, so would be good if one of us could think of a simpler solution.
Maybe worth having another look into the mini pulse3 based round the Amega 8 because the final seems to have ended when certain metals could be detected with certain hex codes,without changing any components but todate couldnt work a code out that would cover everything.
You know ive got all the bits, circuit various hex codes and even made the PCB, its all in shoe box, maybe would be worth me constructing it and see if I can stimulate some interest with the clever people here in this forum.

Regards

Great reply, thanks.
I am no PIC expert, far from, just getting into it, but I read a lot, a real lot and I do believe that we might be able to use these small computers far more, and not just in MDs, but in many other things too, just like the big manufacturers have done for many years.
regards
Andy

[satdaveuk]

Great reply, thanks.
I am no PIC expert, far from, just getting into it, but I read a lot, a real lot and I do believe that we might be able to use these small computers far more, and not just in MDs, but in many other things too, just like the big manufacturers have done for many years.
regards
Andy

Im same as yourself Andy very new to it, can flash a chip but thats where it ends , some of the younger ones on here should be able to help because they been brought up with it.
When i first started my training as a tv engineer it was valves and transistor radios hadnt long been out using the old 0c44 and later ac127/128 etc and what a advancement that was, sinclair calculator came out in my 4th year but we were not allowed to use in exams had to be slide rule.
Im harping on sorry lets get back to the nitty gritty

[6666]

Waikiki_Sweep
Thanks for your reply on your coil info, you have covered a lot of ground there with some good tips
much appreciated , and will put them into practice.

[der_fisherman]

Im same as yourself Andy very new to it, can flash a chip but thats where it ends , some of the younger ones on here should be able to help because they been brought up with it.
When i first started my training as a tv engineer it was valves and transistor radios hadnt long been out using the old 0c44 and later ac127/128 etc and what a advancement that was, sinclair calculator came out in my 4th year but we were not allowed to use in exams had to be slide rule.
Im harping on sorry lets get back to the nitty gritty

We must be of a similar age!!! I will be 66 in October....
Hail fellow well met!!
Andy

[satdaveuk]

We must be of a similar age!!! I will be 66 in October....
Hail fellow well met!!
Andy

IM 55 in august, started my aprenticeship when 16 after leaving school, you proberly look younger than me as ive had a hard life haha

[der_fisherman]

IM 55 in august, started my aprenticeship when 16 after leaving school, you proberly look younger than me as ive had a hard life haha

......and you still remember slide rules!!! Well done.
regards
Andy

[Waikiki_Sweep]

Discrimination of ferrous targets in PI detector.

OK. Here some useful info.

Quote:

"SSP-2010. This is an unique system, combining PI detector and magnetometer, allowing the discrimination of the unwanted ferrous objects no matter their size and ageing in the ground."

"Detech Ltd is the first company in the world, applying search coil with built in magnetic sensors in the middle sector. This allows perfect discrimination of the ferrous objects by the PI detectors."

http://www.detech-metaldetectors.com/about-us.html

So I have found easy to build magnetometer on 555 timer.

To build one you have to find magnetic security strip
http://www.ebay.com/sch/i.html?_nkw=...ic+Ultra+Strip
in one of your books, drugs or electronic goods. Remove Metglas strip
from it and use it as a core for your magnetometer coil.
(there is 2-3 strips inside the tag but only one is Metglas, others are magnets)

I did not tried it yet but it looks very promising.

http://www.youtube.com/watch?v=dP84iJlQCDI

Enjoy!!!

[goldstar]

.

Should I wind my coil in a flat possition like the one on the picture or it doesn't matter?

[Waikiki_Sweep]

Coil for Surf PI

.

Should I wind my coil in a flat possition like the one on the picture or it doesn't matter?

In my beliefs it is the best shape for PI coil to search in water.

[6666]

How did you physically hold the wire while you wound the coil so you could get the zig zag pattern ?

[Waikiki_Sweep]

How did you physically hold the wire while you wound the coil so you could get the zig zag pattern ?

To make such coil you need that tool for winding spiral coils (two plates with spacer between) but you have to make spacer a little bit thicker.
Let say 1.7 of wire diameter. Sure you will not have ideal zigzag but something very close to it.

[6666]

Thanks for the explanation about making the coil, thats very clever ,
I was originally thinking along the lines of you having a single dummy winding to start it
Cheers

[goldstar]

For some reason I can pick all types of metals, including Silver. But not 14k gold, only 10k gold and I think that I can pick 10k gold because is not that pure. Why? should I work on my coil to do it better? I got a signal on a medallion and when I bring it home the first thing I did is to pass it near to a magnet and it stick it to the magnet and ... I try differents setups using some 14k gold chains and nothing.

[der_fisherman]

For some reason I can pick all types of metals, including Silver. But not 14k gold, only 10k gold and I think that I can pick 10k gold because is not that pure. Why? should I work on my coil to do it better? I got a signal on a medallion and when I bring it home the first thing I did is to pass it near to a magnet and it stick it to the magnet and ... I try differents setups using some 14k gold chains and nothing.

I read on here time and again that some PI detectors have problems with Gold as due to the fact that it has a very low resistance, the induced target signal is basically shorted out very quickly. You need to sample sooner than you are doing.

Conversely, if you sample fast enough to detect gold, other more resistive (slower) metals will be missed.....which is why some PI MDs have an adjustment for that.....

I did recently suggest that having a programmable PIC to do the job, it could be quickly switching back & forth, so catching all metals....

This is all hearsay as i do not have a PI detector myself....

Best of luck

andy

[TH Jim]

Hi Goldstar,

The reason you are not getting very good results using chains is that chains are very difficult to detect. Each link behaves like an individual target, with each magnetic field orientated in a slightly different plane, so many fields will cancel each other out. The net result is a very small target.

As an example, i have tested my PI with a 20 gram, 22k chain and it can barely be detected at a distance of 2 inches. Compare that to a 22k mans finger ring of only 7 grams that is easily detected at a distance of 12 inches.

As long as you sample somewhere between 12 and 20 micro seconds you will be ok to detect gold rings

Cheers, Jim.