Led output for Surf PI

[ApBerg]

Hello Ant,

Congratulations! my first experiments were not that good !
Now I use for closing the tube some nylon plugs that I hit with a hammer in the tube ends, that way the sand is even more solid in the tube.

Success with your creation !

Ap

[ApBerg]

Hi ApBerg,

That is a very nice detector you have made - congratulations! Can I say thanks to you for putting the long print PCB on this forum, it has helped me a lot. I made it about 1 year ago and have used it to find many gold rings at the beach. I was already thinking of making a coil in the way you have when I read this thread, but I am wondering how do you shield the coil?

Regards, Jim.

Hello Jim,

Fist I love to hear that you have made some good finds !!

As for screening.... yes that is a little hard to make, but for searsing at the beach I think that your delay adjustment is that far away that screening is not really necessary?
I am not an expert in beach hunting.... so if anyone has an opinion ?

Hope you make many more good finds !

Ap

[ant]

Took a bit longer than expected (not enough free time). Thanks again for the instructions and inspiration

Here are the results:

[TH Jim]

Shielding question

Hi ApBerg,

That is a very nice detector you have made - congratulations! Can I say thanks to you for putting the long print PCB on this forum, it has helped me a lot. I made it about 1 year ago and have used it to find many gold rings at the beach. I was already thinking of making a coil in the way you have when I read this thread, but I am wondering how do you shield the coil?

Regards, Jim.

[ant]

That was an excellent set of instructions, thanks very much. I wouldn't have thought to pack the sand in there. I have some 'sand blasting' sand that is very fine, I'll give that a go.

I'll give it a try over the weekend and post some photos (successful or not) after then.

Once again, thanks.

Ant.

[ApBerg]

UW use coil

If the coil is ready and working ....you can fill it with epoxy or polyester.
The pvc tube that is going to the upper rod you can also fill with epoxy or polyester fiber this make's a strong sears rod for UW use, the cable is inside the rod so also less resistend in the water.

Susses

Ap

[ApBerg]

Work flo

Schematic how it can be done.....
The pvc pipe is in gray and filled with dry sand, heating for bending: do this with a electric paint stripper, not a torch... this burns the pvc..
Blue is solid wood circle...
Start with the small circles, this way you can, when bending the large circle, allign the endings in line....
Succes

Ap

[ApBerg]

Made some photo's ...

The first and the last turn go also in the tube before shifting the T junction in place. You have to mark this turns so you can see witch wire you have pull out the tube when the T junction is in place....

Succes...

Ap

[ApBerg]

Bending PVC

Hello Ant,

Bending from PVC tube can be done by filling the tube with fine dry sand.
The sand needs to be very solid in the tube, the ends can be closed by some tape . If you now take a electric paint stripper and carefully heat the tube you will see that when hot enough you can bend the tube very easy around a round form. Use some gloves !!
The copper wire can be pulled through the tube with the use off a thick nylon wire. I use a coax cable, stripped from outside isolation and screen wire .
I can make some photo's if you like.. (in the weekend)

Best regards.

Ap

[ant]

Hi ApBerg and everyone

I'm new here but love what I've seen so far.

I'm waiting for a couple of kits from Silverdog, and in the meantime looking around for ideas on the housing. I love the design you have come up with here, but am wondering how you got the coil in there?

Did you cut the pvc? Wound the coil by feeding it thru? Sorry if this is a basic question, I'm quite new to it all. Also, How did you bend the PVC, with heat?

Thanks,
Ant.

[ossamaussama]

white surf master

i try the led instead of speaker it work fine

and i found that the there is saturation opamp problem

so i put opamp offset adjustment in the last stage

dc stage
also i am thinking of gain control like surfmaster II

iam working now for convert the surfmaster to work like delta pulse

that is VCO using 555 timer

[sm876]

Stefano,

You should definitely read the following article by bbsailor, it's an excellent article about coil building. You'll learn about the important coil parameters and shielding.

http://www.geotech1.com/pages/metdet...s/FastCoil.pdf

Regarding the resistance of your coil, reducing the gauge of the wire will increase the resistance. The parameters that ApBerg and I provided in the previous posts should get you there.

Thanks for the info, i'm going to study the coil article ... i hope to understand ...
after I'll post the new result ...

Regards
Stefano

[hobbes_lives]

Stefano,

You should definitely read the following article by bbsailor, it's an excellent article about coil building. You'll learn about the important coil parameters and shielding.

http://www.geotech1.com/pages/metdet...s/FastCoil.pdf

Regarding the resistance of your coil, reducing the gauge of the wire will increase the resistance. The parameters that ApBerg and I provided in the previous posts should get you there.

[sm876]

Hello hobbes_lives and ApBerg,

Now I will try to build a coil with the appropriate parameters you suggest me.
I'm sorry but I am beginning with the MD so
I don't understand the meaning of your questions about
"if I shield the coil and if I leave a gap in the shield?"
Could you please be more clear,
or could you please tell me where I can find info abaout that?
I made a classic coil (posted below) with a diameter of 23 cm,
then I attached the coil with 2 short cables directly to the PCB,
just for testing.

I have a question:
I read the posts in the forum, and I saw that everyone has a coil resistance much greater than mine, as is it possible?
Have I got to solder an extra resistor in serial with the coil?

Yes I have a digital oscilloscope, and I have test the output of the FQP12P20 (DRAIN) and I saw un impulse at 638 Hz of frequenzy.

I'm glad of this forum, all you are helping me a lot to understand the MD.

Thank you very much.

Regards
Stefano

[ApBerg]

Hello Friends,

Thanks Esteban ! In the past I made some more experiments with led's, with poor results. Now there are the Luxeon leds that have very strong results ( take care for your eyes !!) If you place a colored led in white nylon you can even see signal at sunny daylight. Minor point.. they can get hot if to must power is added.
Thanks Hobbes for helping, this is a nice forum !

Good luck all.

Ap