Whites Surf PI schematic

[Tita]

Hi there!
This is my first post on the forum
And i hope that my english isn't so bad!
I finalizate the surfmaster PI a couple weeks ago and it is not working very good
One day is working..the next day isn't(beeps in continuu).
The solder joins ,traces and the parts placement are good.
And when is working in does not detect gold....it detects cooper and iron..
My cellphone at 30cm.
And a coin at 18-20 cm.
The voltages are ok....i have a signal at pin 3 of the 555 timer(at approximate 600Hz).
I don't have an oscilloscope....i measured the frequency with the multimeter.
The coil is 25 cm in diametre 19 turns.
Any ideea what could be rong?
http://postimg.org/image/phfmtmlhx/
http://postimg.org/image/hhq57h93z/
http://postimg.org/image/xk2ih39yp/
http://postimg.org/image/x7w29mjit/
I removed the ic-s sockets an solder them directly to the bord

[daverave]

maybe you got the sample pulse in the wrong position...if the sample too late position then it will only mainly be sensitive to copper coins and iron items and will give poor depth on gold or low conductive items.

[Tita]

And how i can adjust the sample pulse?
I adjust pin 6 on NE5534 at 0 volt.
And i adjusting the delay and threshold and nothing is happening...when i adjust the threshold the sound increases..and when i adjust the delay the sensibility increases or decreases.....and still is not detecting gold

[daverave]

without a oscilloscope you can slowly adjust the delay until the threshold starts to jitter...the threshold needs to be adjusted until you start to hear the audio tone....if set too low or too high you will loose depth...if this fails then you need to think about the coil and damping resistor to see if they are correct...on my surf pi i used normal copper wire about 32 swg and about 400 uH with a damping resistor of around 390 ohm...if you use wire that is too thick gauge it will affect depth...you need first to get all these basic parameters correct to get good depth on gold and low conductive items.
Also try and wind a 12" coil which is a good size for most treasure items.

[Tita]

Yes i adjust them correctly and it's still not detecting my gold chain......it's detecting a coin at 20-23 cm ..........
I don't understand why at least a weak sound at 1 cm...but nothing).

[Old cart]

Yes i adjust them correctly and it's still not detecting my gold chain......it's detecting a coin at 20-23 cm ..........
I don't understand why at least a weak sound at 1 cm...but nothing).

How fine is your gold chain? If it is very fine it behaves as if it is a bunch of individual targets. This may be completely normal.
Is the coil shielded? If so with what and does it form a complete loop?

Try the following steps. After each each step carefully adjust the threshold for a minimum audible tone.
Make sure the coil is at least 3 feet from any large metal objects.
If you have US nickel use that as test target. If not try the pull tab off a soda or beer can. Lacking those try a 1 inch square of tin foil. Any test target must be moved quickly to get maximum depth. Experiment to find out the best speed.

1. Set the delay pot to minimum resistance which is minimum delay. Test
2. Double check the board against the board layout to make sure there are no shorts between traces. The board does not look like it was cleanly etched. If there are shorts cut the trace with a sharp knife like an exacto knife. Test
3. Test and report the battery voltage after the detector has been running at least 1 minute.

[Koala]

Yes i adjust them correctly and it's still not detecting my gold chain......it's detecting a coin at 20-23 cm ..........
I don't understand why at least a weak sound at 1 cm...but nothing).

Sounds normal for a ladies pendant chain. Sometimes the clasp is the only bit that's detectable.

[Tita]

Can someone tell me what is current consumption of the surfmaster PI?

[Old cart]

Can someone tell me what is current consumption of the surfmaster PI?

about 100 mA?

[Old cart]

I am writing a build guide for the Surf PI V1.2 as sold by Silverdog. It is about half way done. I plan on adding a complete schematic to the guide. I have the schematic off of Silverdogs site but it is a PDF which I can not edit. It could use editing for clarity. Does anyone have an editable version of that? I think the original was down by Ap berg.

I am writing the guide based on the Minipulse so if you have any ideas or thoughts pass them on.
thank you.

[daverave]

if its a thin gold chain your asking a lot for a unmodified surf pi to detect that....some commercial pulse detectors cannot detect thin gold chains...you would need a fast coil to give you about 8-10 uS delay and maybe a higher frequency coil drive around 3 khz....try a US nickle coin and that will be a good test as a low conductive item.

[Tita]

i don't think that it's so thin.......it has about 7 mm
https://www.google.ro/search?q=gold+...HZc92fFThoM%3A

[daverave]

yes the surf pi should detect your 7mm gold chain...not sure what depth you would expect on that as ive never tested with 7mm chain...you really need a scope to see whats going on in the circuit...ive made 4 surf pi's and never really had much problem with them.

[FatBob]

Here's a Schematic I drew in Express for Old Cart and others to be able to edit;

[Tita]

i don't have an oscilloscope
My question is....what part of the circuit should be responsible for this?