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

[plumabob]

Hi N1PS,

Board was fine, my adjustments were way off. I haven't noticed any heat problems but it's only been on for maybe 15 minutes or so.

Regards!

[N1PS]

OK Success!

With an 11.5 inch mono I can hit the same nickel at a foot. Specs as follows. 22awg teflon coated stranded wire, .308mH .96R.

Use a set of headphones to zero in your settings ...works a lot better.

Great on getting it working well. Did you need to perform any PCB corrections? Reading some of this thread and others, there may have been a jumper or two to add/fix? I have not built mine as yet.

Did you have any issues with the FET getting warm with the 11" coil?

On the headphones - I noted that several detectors use a 555 audio chip in astable mode, creating basically a voltage controlled audio oscillator...driven by the integrator chip. If I understand these 555 output detectors correctly, this circuit would give perhaps a more pleasing audio response, ...and if you drive a speaker with a transistor (or darlington pair), you would get a lot of audio output. But I am not certain I understand the 555 audio circuit as used in those detectors so I could be way off base.

Also, I plan to add a meter to detect the audio. I like a meter...it is more sensitive than the ear (especially my ears ). I have tuned receivers for years with a meter (such as AVC or S meter).

Peter

[plumabob]

OK Success!

Got the bugs worked out and the settings zeroed in. Using my 9 inch mono coil I can hit a nickel at 9 - 10 inches, so I guess that's pretty good. Signal is faint but I would dig it for certain. Coil specs are as follows 21awg magnet wire, .330mH and 1.26R.

With an 11.5 inch mono I can hit the same nickel at a foot. Specs as follows. 22awg teflon coated stranded wire, .308mH .96R.

Use a set of headphones to zero in your settings ...works a lot better.

Great little PI Silverdog...very happy.

Thanks again,

Bob

[ApBerg]

"but if you use the tune potentiometer then you must get a point that is giving a continuing sound"

Yes there is a sound but it disappears after a short moment maybe a half second. Sounds like it drifts away. Should i use a fine tuning Poti with more turns? The on i have can only be turn in an ancle of 270 degrees maybe thats not fine enough.

No need for a multiturn potentiometer, if your sound drifts... check the E caps if they are in good directions on the board .. and put the other trim pots in mid position then test again ?

Ap

[silverdog]

Bob

have a look at this thread http://www.geotech1.com/forums/showthread.php?t=17240

Silverdog

[plumabob]

OK Silverdog,

It's working correctly now. I do have a scope. How would I go about hooking it up and tuning the board in for max performance.

Thanks

Bob

[bernte_one]

countinuing sound

"but if you use the tune potentiometer then you must get a point that is giving a continuing sound"

Yes there is a sound but it disappears after a short moment maybe a half second. Sounds like it drifts away. Should i use a fine tuning Poti with more turns? The on i have can only be turn in an ancle of 270 degrees maybe thats not fine enough.

[ApBerg]

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?

ps
thanks APBEG
thanks SILVERDOG

Hello Bernte,

It is ok that you do not have a clicking sound, but if you use the tune potentiometer then you must get a point that is giving a continuing sound.
The best setting is to the point you just get a little noise.
A euro can be detected around 25 cm, test with the setting from the delay potentiometer.

The PI detectors that have a click output use a VCO. In the Surf this is not the way the audio sound is made. A switch from the 4066 is used to connect the DC output from the lm358 in a freq. from around 660HZ to ground, this make's the 'sound' in a fixed freq.

The test points are for use with a scope, so you can make a little pin there, put it is not needed to do so.

Succes.

Ap

[bernte_one]

some questions

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?

ps
thanks APBEG
thanks SILVERDOG

[jmoller99]

Thanks for the Russian Link. I see that the Offset pot is the only one I will leave on the board. The others will be moved to the case. It also has the following coil info:

With the parts list...
Search Coil Data:

Wire gauge is 0.5 m.m. metric or 24 gauge standard copper"enamel coated"
Diameter: 9 inch or 23 c.m.
number of turns approximately 20 ***

And another coil test file:
DIMETER TURNS WIRE INDUCTANCE RESISTANCE RESULTS
21 19 0,25 279,8 uH 5,2 16 cms
21 20 0,25 313,7 uH 5,3 13 cms
21 22 0,25 343,2 uH 6,5 14 cms
21 23 0,25 372,4 uH 6,0 14 cms
21 24 0,25 406,5 uH 6,1 14 cms
21 26 0,25 498,8 uH 6,8 14 cms
21 27 0,25 538,3 uH 7,0 15 cms
21 28 0,25 575,8 uH 7,0 16 cms
21 29 0,25 617,4 uH 7,6 14 cms
21 30 0,25 664,4 uH 7,6 13 cms

As well as the following file for adding a pin pointer mode (note the resistor R numbers don't match the Surf PI Schematic, but its easy to locate the place to add it):

[dfbowers]

HELP!!!


Got my board completed. None of the pots are doing anything just getting a constant tone. When I turn each pot there is no change at all. The volume works as I can adjust the loudness but the coil is dead. Here are some pics maybe I screwed up somewhere.

I don't see anything wrong from the pic.
Do you have a scope?

[ApBerg]

HELP!!!


Got my board completed. None of the pots are doing anything just getting a constant tone. When I turn each pot there is no change at all. The volume works as I can adjust the loudness but the coil is dead. Here are some pics maybe I screwed up somewhere.

Hello Bob,

You have sound, so there are 'things' working. Put all pots in mid position.
Check now if your tune pot is working, it can be that you have to turn it (counter) clockwise to make the sound go away...

Succes

Ap.

[plumabob]

d1+ d2 are where they are suppose to be with the correct orientation. Is that what you are asking?

[maikl]

D1 - D2 ???

[plumabob]

HELP!!!


Got my board completed. None of the pots are doing anything just getting a constant tone. When I turn each pot there is no change at all. The volume works as I can adjust the loudness but the coil is dead. Here are some pics maybe I screwed up somewhere.