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

[multieagle]

Where do you place the oscilloscope probes to measure coil decays? Is there somewhere a thread on calibrating the Surf PI 1.2 ? Tks.

[Waikiki_Sweep]

Connect oscilloscope to preamp output pin (6) of NE5534. Debugging of SurfPI unfortunately scattered over many threads. This one you are reading now may helps too.

[bklein]

Why no foil in coax? Most hf coax has foil. What do you use then?

[Waikiki_Sweep]

Foil acts like a target, just like small gold ring.

You can find coaxial cable with cooper wires mesh instead of foil, also center conductor is better if it is stranded or you will detect solid wire in it.

In many cables also you will see a Mylar screen that looks like an aluminum foil but in real it is a plastic with very thin aluminum layer made with vacuum emission.
That is practically undetectable or making very low signal so probably you can use it. (Try to detect piece of cable with your detector to be sure)

Also hook it on LC meter and check capacitance. Lower is better. Thin cable tends to have more capacitance and it will make your coil slow decaying.

I tried "Belkin Synapse Gold Plated Video RCA Coax Cable" for monocoils but it has a Mylar shield over cooper stranded wires shield. Central conductor is stranded as I need. It works fairly good.

For DD coils I am using "Belkin Synapse Silver Series S-Video" because of two insulated stranded coaxial cables inside with separated not connected together shields, stranded cores and even no Mylar.
It fits specification perfectly!!! If you cut Minelab Excalibur or Fisher CZ or most other VLF detector cables you will see the same picture.
Just one drawback. It full of woven instead or plastic cords. May suck water. But two years of use on salt water beach shows OK!

Also that Belkin cables are very robust and will survive a lot of bending and other mechanical damage when you will use if in field.

But most of other S-video cables on eBay are scam: 4 wires in one shield (too bad!) or shields touching each other (bad!).

You can find many good cables once you know what to searching for.

[bklein]

OK, that's right I remember now testing I think some USB3 cables and they were detectable by the coil.
In regards to the series diodes, I just came across this article: http://www.eecs.berkeley.edu/Pubs/Te...-2012-265.html
I may be off-base but perhaps some of the design techniques apply.

[itsazoo2013]

How do I go about ordering a Surf PI kit from your webpage?

[Waikiki_Sweep]

How do I go about ordering a Surf PI kit from your webpage?

You can find it here: http://www.silverdog.co.uk/shop/inde...&product_id=76

[itsazoo2013]

I tried that already. Says my email is invalid. Also gives the amount in British pounds. Is there one for American dollar?

[Waikiki_Sweep]

I tried that already. Says my email is invalid. Also gives the amount in British pounds. Is there one for American dollar?

Try to Send Private Message to the shop owner - silverdog or send him email or use "Contact Us" on his website:http://www.silverdog.co.uk/shop/inde...mation/contact

I think if you will use PayPal it will convert you payment to dollars automatically.

[itsazoo2013]

Thanks Waikiki. I tried buying as a guest and tried contact also...it went back to login...which said invalid email. So obviously I'm not doing something right. HA

Anyway...thanks for the info.

[Qiaozhi]

Thanks Waikiki. I tried buying as a guest and tried contact also...it went back to login...which said invalid email. So obviously I'm not doing something right. HA

Anyway...thanks for the info.

It sounds like you're trying to log in as a Returning Customer. First you need to click on the Continue button under "I am a new customer".

[rompingdog]

Hello all.
This post might not be in the right place, but here goes anyhow.
I have built the surf PI board as per the parts list and schematics. So far so good. Built the coil and am getting some sort of detection of metal at about an inch with a fairly largish chunk of metal, but I think from reading other posts, my wire might be a bit weedy and the turns slightly incorrect. So that I can get around. But, the problem I cannot seem to fathom is why the speaker is barely audible. The gain pot and volume seem to be installed correctly (well the volume switch sort of gets the speaker making a feeble squeak when the volume is turned all the way to the end stop and the gain does what I would expect it to do, stop the feeble squeak at about one third turn). So can anyone tell me please why the speaker is barely audible? Have I installed the speaker wires onto the board wrongly? There seems to be a hole above the three where the molex connector is that appears to be electrically connected to the speaker, but nothing in terms of a resistor or any sort of link seems to go there. Should I have something in this hole? Forgive the way I put that by the way. Any help here gratefully received.
Dave

[silverdog]

A photo would help a lot
Start with your voltages, what do you have on the 7660 pins 5 and 8 ?
What wire is your coil made from, what diameter is it and how many turns ?

[rompingdog]

Hi Silverdog.
I'll get the necessary photos on here a little later.
Just a quick overview.
The coil is one of three I have, first is 26SWG at about 21 turns in a bundle as it were and not flat wound. The second is same SWG and wound to 29 turns, again not flat wound and the third is a twin speaker wire at 29 turns and is 13 strand maybe 30swg but this time flat wound with both conductors joined together to effectively make one wire as it were. Doesn't matter which coil I use, the speaker is almost inaudible, which is the bit I am really confused by. The flat wound coil is 20cm in diameter and the two enamelled wire coils are 19cm apiece. Pin 5 on 7660 has 4.92v and pin 8 has -4.6v. I'll get a picture up as soon as I can.

[der_fisherman]

Take a magnifying glass, start with all the resistors and the multiplier, make sure that every resistor is in the correct spot and all soldering is perfect.
Then check each capacitor.
Then the rest of the components.
I have been building electronics since the middle '50s, but I still sometimes place a component wrongly.....sadly!!! I usually find the mistake when the component I need is missing, so I look back to where I have already inserted a similar component......
Always measure each resistor and capacitor before inserting and soldering, as when tired, a 4.7KOhm, can look like a 47KOhm......or for example, a 10pF cap like a 10nF cap....
Sad but true!!!!
Wrongly wired switches need proper through measuring with an Ohmmeter.....
Log pots must be correctly wired, well all pots need to be correctly wired!!
Some replacement transistors have different pin orientation and just following the printed component shape could prove wrong.....
You have probably got some or all of the above problems and may have damaged a component......