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

[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

[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 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

[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.

[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

[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]

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

[der_fisherman]

Gold decays fast. To detect gold you need shorter delay. With longer delay you can see that 25 cent coin detects from same distance or even far then gold ring.

With delay less then 20-25 mks gold ring may detects twice far then 25 cent coin.
I have experimenting with some timing adjustments and have 30 cm for gold ring and 7 cm for iron hummer at the same time. Looks ridiculous. But short delays make it very noisy for practical use in salt water. (May be good for dry sand but for dry sand VLF detectors are much much much much much better)

Anyway I keep my delay around 20 mks in salt water and dig most gold even if I left some coins undetected.

So if you can not detect your coil with another PI detector you will have coil fast enough to detect GOLD, platinum, small gold and anything that decays fast.

If I understood you fully, you need different settings for different metals.

Have you possibly given some thought to just how many settings are needed to say cover all the "wanted" metals?

If I guess at say three for the moment, have you possibly considered a method whereby say a PICAXE chip switches between all three in a sequence dictated by the pulse frequency of the metal detector?

So say for pulse one is for Gold, pulse 2 is for say copper and pulse three for steel and iron....maybe more are required.....

It may be that you need to have more pulses for each metal type so that the detection is made more audible, say 10 of each for example.....(I am just guessing numbers at this time).

You may need to add some pulse lengthening to make any received signal perfectly visible.....also maybe a different tone for each metal type......again a PICAXE would appear to be perfect for the job....

With a PICAXE (or similar PIC) and a small amount of programming, you could easily switch between setups, or even pick just one or two say and ignore some metal types completely....

This has only come from my head, it has not been tested in any practical manner at all and may therefore not have any worth at all.....

Best wishes

Andy

[satdaveuk]

It was 13-15 cm for 6 mm. wide 25 gram marked 14k gold chain. but few days ago I have made some changes to the schematic.

I have increased gain two times by changing integrator RC values.
It gave me range 35 cm for gold rings but it starts "motorboating" in shallow water.

To stop "motorboating" sound I have reduced dumping resistor significantly.
Now I still have 35 cm for gold rings but range for this gold chain drops to 6 cm.

I have another chain same size and weight and it detects at 25 cm. Probably it is gold plated or contains more cooper because little more red in color. (Lock lost so I have no idea what hallmark was, but it appears dense like gold)

Gold decays fast. To detect gold you need shorter delay. With longer delay you can see that 25 cent coin detects from same distance or even far then gold ring.

With delay less then 20-25 mks gold ring may detects twice far then 25 cent coin.
I have experimenting with some timing adjustments and have 30 cm for gold ring and 7 cm for iron hummer at the same time. Looks ridiculous. But short delays make it very noisy for practical use in salt water. (May be good for dry sand but for dry sand VLF detectors are much much much much much better)

Anyway I keep my delay around 20 mks in salt water and dig most gold even if I left some coins undetected.

Also I can say that good coil for PI detector is coil that can not detect itself.
Check all components you want to use to assemble your detector WITH ANOTHER PI DETECTOR.

If you can detect your wire with another PI detector than it is bad wire. Use stranded wire with thin strands.

If you can detect your shield material than it is bad shield material. Use graphite powder and some resin or lacquer 1:1. I have used mylar film. It is not detected by PI but looks like resin chemicals or salt water have destroyed it in time.

There some ideas to use lead wire (like solder wire) or heating element wire from toaster
to connect shield. Because thin lead wire or tungsten wire you can not detect by PI detector because of high resistance.

If you can detect your coaxial cable it is bad cable. Use twisted pair of stranded wires at least first few inches from the coil.

And sure no metallic parts like bolts or pipes closer than two feet from coil.

So if you can not detect your coil with another PI detector you will have coil fast enough to detect GOLD, platinum, small gold and anything that decays fast.

Very useful tips shall keep all that in mind.
Far as shielding todate my best results have been using synthetic graphite, which is around 98-99% carbon mixed 1:1 with hardglaze varnish with a very small drop of the original tupintine, mix then just brush on as required
Goes off really hard and doesnt crack or at least hasnt for the last few months of trials, also good on styren housings just make sure you sand the gloss off first otherwise doesnt stick.
Its goes off like a very dark gray paint and can be sanded to give a smooth finish.
Not tryed it on PI only IB, in the middle of putting a Bara together to do some experiments so will let you know.

All the best
Regards

[Waikiki_Sweep]

Waikiki_Sweep

just wondering with your thin coils in the water what is their sensitivity like to thin gold chains ? thanks

It was 13-15 cm for 6 mm. wide 25 gram marked 14k gold chain. but few days ago I have made some changes to the schematic.

I have increased gain two times by changing integrator RC values.
It gave me range 35 cm for gold rings but it starts "motorboating" in shallow water.

To stop "motorboating" sound I have reduced dumping resistor significantly.
Now I still have 35 cm for gold rings but range for this gold chain drops to 6 cm.

I have another chain same size and weight and it detects at 25 cm. Probably it is gold plated or contains more cooper because little more red in color. (Lock lost so I have no idea what hallmark was, but it appears dense like gold)

Gold decays fast. To detect gold you need shorter delay. With longer delay you can see that 25 cent coin detects from same distance or even far then gold ring.

With delay less then 20-25 mks gold ring may detects twice far then 25 cent coin.
I have experimenting with some timing adjustments and have 30 cm for gold ring and 7 cm for iron hummer at the same time. Looks ridiculous. But short delays make it very noisy for practical use in salt water. (May be good for dry sand but for dry sand VLF detectors are much much much much much better)

Anyway I keep my delay around 20 mks in salt water and dig most gold even if I left some coins undetected.

Also I can say that good coil for PI detector is coil that can not detect itself.
Check all components you want to use to assemble your detector WITH ANOTHER PI DETECTOR.

If you can detect your wire with another PI detector than it is bad wire. Use stranded wire with thin strands.

If you can detect your shield material than it is bad shield material. Use graphite powder and some resin or lacquer 1:1. I have used mylar film. It is not detected by PI but looks like resin chemicals or salt water have destroyed it in time.

There some ideas to use lead wire (like solder wire) or heating element wire from toaster
to connect shield. Because thin lead wire or tungsten wire you can not detect by PI detector because of high resistance.

If you can detect your coaxial cable it is bad cable. Use twisted pair of stranded wires at least first few inches from the coil.

And sure no metallic parts like bolts or pipes closer than two feet from coil.

So if you can not detect your coil with another PI detector you will have coil fast enough to detect GOLD, platinum, small gold and anything that decays fast.

[goldstar]

"R16 up in that resistor on the board" is a white line that looks that I had to solder a cable. Its correct? I have to solder a cable betwen pin 11 of the U7 and diode D3?

[6666]

Waikiki_Sweep

just wondering with your thin coils in the water what is their sensitivity like to thin gold chains ? thanks

[Davor]

Thanks.
I am in a process of picking one simple PI to build, simply to get a whiff of it, and then proceed in some other direction. The obvious choices are barracuda and surf.

[ApBerg]

Now that you are stirring some strange waters, would you care to elaborate this conclusion in a few more words?

Thanks for asking.

Yes .... mostly just feelings... and some small things, I find the Barracuda easier to assembly, less parts ? (and there is a ready made pcb for it).
The barra it a little more tolerant to coils, I had a 50 cm coil that run on the barra and had no luck with the surf. The barra has some more depth.. ca 3-4 cm on a gold ring for a 22 cm coil.. but if you replace in the Surf R2 ( near the 555) from 3k9 to 4k7 sense is almost the same..
Not great different... mostly feelings .... love the simplicity from both circuits that give such good results.

Best regards.

Ap

[Waikiki_Sweep]

Probably they put RG45 network connectors on 8-core alarm cables then sell it as Cat.5.
Network cables. Never tested it in my home network. Do not expect it will work good even for network connection.