My Surf PI works - thanks Silverdog and ApBerg

[golfnut]

With the Surf Pi the de Q ing Resistor slugs the ringing following a Tx spike,

it also is wired across the Rx input - slugging the return from the coil!


With separate Tx and Rx coils - the Rx coil will not have the loss introduced from the D Q resistor.


How much better would this be .

What results are people getting on these Surfs?

Steve

[woodbob123]

Thanks to all

finished my first surfPI thanks to all who have worked on design, nothing nicer than when when you put a project together and it works first time all the credit goes to you guys. Put together a nice coil and finish this one, hopefully the IGSL will go together as nice

THANKS TO ALL

[Sean_Goddard]

Sadly, somthing came up and I was unable ot take pictures of the waveforms (actually I'm STILL working on MY SM) but my friend has had to go back to base for posting.

We too some measurements of the Whites Dual Field coil and here is what we found;

R = 2.4 Ohms
I = 253 uH (1KHz)

That's the best I could do for the moment. Sorry.

[silverdog]

Have you seen this ? an error has been found which when corrected should improve your detection range


"Remember to swap your R18 and R22 around - as typo on the silk screen.

Use details to improve depth as in the link

http://www.geotech1.com/forums/showthread.php?t=18445

PCB and Schematic were ok - just typo on the silk screen.. "

[TH Jim]

Hi Sean,

Those results are very impressive - could you post a picture of the ring you used or tell us it's weight and dimensions please? Similarly details of any other targets you use when you perform your comparison test would be good know.

Look forward to seeing your results, thankyou for sharing with us. Happy new year!

Cheers, jim.

[Comp]

What values ?
thanks

I'm still bothered by low sensitivity on mine, too,... I get the same 80mm or so on a gold wedding ring..... I am 'tweaking' the supply lines to get em nice and clean,..... I have put a small red led in the ground lead of the 75l05, this is fed from the 12V line by a 4.7K resistor,... serves two functions, it gives me an on/off indicator, it also 'upps' the 5V line to 6.5V, or so, & the same with the neg 5V line, to minus 6.5V. I am filtering the plus and minus supplies to each chip with 47 Ohm resistors, and 4.7microfarad tant caps, and 0.1mic bypass ones as well, supplies are nice and smooth and clean,....and plus and minus 6V or so at the chips,... I used these values cos I have plenty to hand!!!!!!!

I havent got it quite all back together, yet, I am rebuilding it on 'blob board',.. just in case I have 'leakage' problems on the original board......

I will keep you posted/updated,......


Cheers, Fred

[6666]

Thanks Sean
I will get out the junk box

[Sean_Goddard]

Try a few until you get best results for space / cost taken

[6666]

it might be worth adding an inductor in the supply rails to these chips (thus isolating the TX part from them) and adding a nice FAT electrolyic with a good low ESR.

What values ?
thanks

[silverdog]

Hi Ant,

Glad you got your detector working. I am still building my first SurfPI.

I was looking at your pictures and noticed the 100N cap above the 555 chip appears to be in the wrong place. I think it should be over to the right in the spare solder pad in the picture. I think it is called C16.

In the pictures Silverdog supplied the right hand pin on the cap appears to be in line with the pins on the large cap just above it.

I could be wrong as I am new to this and learning also. Perhaps some more experienced builders could look at the photos and check this.

Hope this helps.

Regards,

Grant

I think it looks ok, for a 5mm box cap
I think in an earlier picture I had used a green film cap and used the spare pad you refer to for the right leg, as the leg spacing on these is much wider

Silverdog

[gcause]

Hi Ant,

Glad you got your detector working. I am still building my first SurfPI.

I was looking at your pictures and noticed the 100N cap above the 555 chip appears to be in the wrong place. I think it should be over to the right in the spare solder pad in the picture. I think it is called C16.

In the pictures Silverdog supplied the right hand pin on the cap appears to be in line with the pins on the large cap just above it.

I could be wrong as I am new to this and learning also. Perhaps some more experienced builders could look at the photos and check this.

Hope this helps.

Regards,

Grant

[Sean_Goddard]

Hi All, I've been working on one of Silverdogs excellent Surfmaster PI kits. We put a Whites dual field coil on it and after a little "tweaking" we now pick up an 18mm 18ct mens gold ring at around 14" (35cm approx) with a clear signal.

We also have access to a REAL Surfmaster which we will be probing tomorrow. SO...to help you ALL I will TRY to post as many 'scope screenshots as we can along with details of what point in the circuit they were taken side by side (Silverdog kit V Whites PI) for comparison.

Silverdog, might I suggest a 100nF across the 4066 AND the 4093 supply pins as I see a lot of "bounce" around there on some of the signals and it IS customary to decouple digital switching IC's anyhow as part of good design practice.

The flyback is around 250V pk=pk and this picks up VERY significantly into the sensitive stages of the detector, it might be worth adding an inductor in the supply rails to these chips (thus isolating the TX part from them) and adding a nice FAT electrolyic with a good low ESR. In fact splitting the supply rails and adding some good filtering might help a LOT!

I also think that building the board and leaving the trimmers off until LAST allows you to soak the board in CLEAN isopropyl alcohol for half an hour or so to remove ALL contaminants, then coating the board with conformal sealer goes a LONG way to making the Surfmaster a LOT more sensitive.

I might also suggest dropping the current IC sockets and using turned pin ones. The reason for this is that flux tends to creep up the legs and onto the contact areas thus causing noisy and intermittent connections.

MORE TO COME!!

[bernte_one]

put videos also here

http://www.geotech1.com/forums/showthread.php?t=17538

[nelson]

Hi and thanks Qiaozhi
I just did it last year, so thanks a lot any way
Regards
Nelson

You can download the pictures yourself by right-clicking on the image.

[nelson]

Hi bernte_one.
Take a look to this test i have done with my first sufmaster i build
Regards
Nelson

http://www.youtube.com/watch?v=WsW4uu_Zf54

What should i connect to the "GND pad" under R5 maybe the housing of pi detector board?

The points TP1 and TP2 are for measuremnts or not?

My surf pi works but don´t get an continuing sound for example a beeb every 5 sec. or so.
Is it right?- i found no videos. At mine there comes a short sound when tuning (i think it is the right point) and i can detect euro coins at 15cm (i know it could be more but it is a problem of my coil). From other Pi detectors i know a clicking sound at right tunig point.

Can anyone Help?