Whites Surf PI schematic

[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]

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]

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]

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?

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I removed the ic-s sockets an solder them directly to the bord

[daverave]

i went to the beach yesterday to test my modified surf pi and i was getting these false bleeps as i swung the coil and i got worried ohh there must be a problem then i sussed the problem !!! i had forgotten to change my shoes before leaving home...i was wearing steel toe cap boots...i felt such a plonker

[ashkelon]

if pulse detector use -5v + 5v power, 9540 irf when you swing the coil unwanted sound occur, i shilded my coil today, gap and connected negative pin battery, same status

[sdesic]

That problem is always there when you have something moving - coil : stem : cable
Detector is detecting it self ... or you have problem with connector - probe to housing

[muddy fingers]

This question has featured on a Minelab "Frequently asked Questions" site. They give the answer, " Usually because you are lifting your coil at the end of the swing- always keep low, slow and level for the entire swing". That makes sense as a right handed person would probably lift their coil at the end of the longer right direction swing but keep it level with the ground and closer to their body on the left direction swing. The sudden lifting probably changes the previously balanced out Ground Effect thus causing the detector to signal. Also, other people give "sensitivity too high" as another possible reason.

[ashkelon]

"seadoggy" i have same problem

[Old cart]

Where did you get that board?

I dont know how fix this,i make new surf pi and same problem it is really annoying when i go search.
i try new coil with shield whit out shield same problem.
also i change cable still same.
I make this surf pi

[ATTACH]34766[/ATTACH]

[seadoggy]

i have no commercial coils at present.....i know shielding is ok so maybe coax cable but not sure.

I try alot different coax cable,problem is still there

[daverave]

i have no commercial coils at present.....i know shielding is ok so maybe coax cable but not sure.

[Qiaozhi]

ive had same problem with both my surf pi's...at the end of swing makes a false signal....i waived a small white magnet in front of my coils and hardly any signal from magnet so i guess it cannot be the earth's magnetic field cancellation so not really sure whats causing this

It unlikely to be a fault with the Earth Field elimination, if it can pass the magnet test.
I suspect it's either a coil cable shield problem, or a loose connection. Have you tried the detector with a commercial coil?

[jladre]

Today i make new Surf PI and new coil shielded but same problem(when swing to right make sound lol)
also i go out from my house its more stable but problem remain.
I dont know what is going on in left side no make sound only when swing to right.
Regards

Be sure that coil is fixed to the housing thay it will not have movement, also be sure that cable connection is properly join and not loosen, check also your board for parts that will shake when have movement.

[jladre]

someone found problem for constant beeps in surf pi.I changed the components 2 times and not forward

Try to used unshielded coil and test if it still constantly beep.