Hi Dotniet, welcome to the forum.
Thanks for your interest in my little project.
I can hardly express how delighted I am that it works!
When I received the kit I was a little surprised that there were no instructions with the kit, but it's really quite straightforward for anyone who knows how to read a schematic, available on the silverdog site.
Once you have the SURF PI kit there are some things which you still have to figure out and were fairly challenging to a newbie like myself:
(some were things I wanted to add)
1. how to make the coil
2. working out how to place the PCB into a box and adding the knobs, switches.
3. where to place the power supply.
4 how to balance the whole thing it so it's not too heavy in the front.
5. should the coil have a detachable cable.
6. adding a headphone option
7. adding a power level LED
8. adding a pin pointer attachment
9. making the detector able to take a Minelab compatible coil.
Assembling the PCB kit is easy as long as you know how to solder properly.
How easy it is depends on your level of experience.
I've only started getting into electronics in the past 12 months. I've assembled less than half a dozen kits. The first was a Theremin, which didn't work (and no, I don't think it can be saved, I already raided it for various components).
I also assembled a pin pointer kit which did work, even though I messed up a bit.
Then I bought a "Teach yourself to Solder Kit" (two in fact, but after completing the first one I didn't want to wait anymore and got right into the Surf PI)
If you've never soldered anything before I highly recommend buying a solder learning kit.
When I ordered the SURF PI, I bought two Surf PI kits, in case I'd ruin something on the first attempt. And while I didn't ruin the first one, I did drop one of the capacitors and couldn't find it, so had to raid the second kit for a replacement capacitor.
I can tell you about the depth on my Surf PI, but other builds will obviously vary depending on the coil and whether or not you add a faraday shield, and I assume that how long your cables are will even affect the depth. I placed my box in front of where I would hold the detector so the cable could be shorter,
So this detector, with this coil is sensing a gold ring at 10 cm in air. And yesterday I found a steel pipe in the ground at about 10 cm. The search pattern is a torus shape, not a cone as I had assumed. So the farthest point is radiating straight out of the windings of the coil, not the center of the disk.
I have a tiny piece of gold which weighs .5 grams and it does not register even the slightest blip when near the coil, but I can detect it with the pin pointer attachment I made.
I live in an area that has a lot of iron in the rocks and dirt and my detector detects all of it! Ground balancing and discrimination are two options which I'm still investigating.
I am reading through a book called Inside The Metal Detector which is a great book, but takes a lot of concentration. It's got all the good stuff. It usually takes me a while to tune my brain to start absorbing all the technotalk and following along with what the authors have written, but they've done a fantastic job of making some very advanced electronics a little more accessible.
There is an article on some guy's blog (adrianandgenese, or something like that) about building the Surf PI kit. It constantly comes up on internet searches on this topic, so I have little doubt you've run across it. Sometimes their server won't serve the page so it's probably getting him more hits than his server can handle. Anyway, he has a step by step guide with links to stuff he recommends for the kit. I did buy the things he recommends, but ended up not using all of it. The batteries (three 3.7 V), battery holder and charger were perfect for this project. However using speaker wire as per his recommendation didn't work for me. I tried using it and I wound the wire using his spiral coil technique but I didn't like the look of it. I eventually decided against it because the spiral shape made calculating the inductance a bit too tricky, for me anyway. I also tried to use the speaker wire and make it a loop instead of a spiral (also 30 turns) but that came in at 270 grams. I figured maybe it could weigh a little less with different materials. Also the speaker wire has 15 strands in it so I was really not sure how to calculate the inductance, and some calculations I did indicated that the way I had made it it would have 1500 microHenrys. At that point I decided to work on making the loop from enamelled copper wire.
To house the PCB I used a box I got from Jaycar, an electronics shop here in Australia which has lots of electronics stuff for hobbyists.
I won't go so far as to say I have a final conclusion as there's always the potential for improvement, but I can tell you that it's a good kit, and very good value for money.
There were some things I bought to make a metal detector which I didn't use, though all this will still come in handy:
Oscilloscope
Lunch boxes (to house the PCB)
PVC piping
Adjustable Regulated Power supply kit
100M spool of speaker wire
MIKRON Coil housing (from Bulgaria)
Double sided tape (I was going to use this for the faraday shield along with aluminium foil, but then found aluminium tape at Jaycar)
Even with all that this was still much cheaper than any Pulse Induction detector I've ever come across.
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« Last Edit: April 03, 2015, 06:38:40 pm by jackofdiamonds »
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