Garrett (pulse) XL 500

[kt315]

[Ferric Toes]

Yes, those are correct.

Eric.

[green]

Yes, those are correct.

Eric.

http://www.geotech1.com/forums/showt...384#post219384

Hi Eric
The schematic reply #31 has the .1u cap. mentioned in above link. Would you suggest changing it to a different value?

[Ferric Toes]

http://www.geotech1.com/forums/showt...384#post219384

Hi Eric
The schematic reply #31 has the .1u cap. mentioned in above link. Would you suggest changing it to a different value?

Definitely. Provided the differential integrator is balanced then you should be able to put a shorting link in place of the capacitor.
In the original of this circuit I used a 22uF 6V tantalum cap with the negative end to the preamp. I then set the preamp offset to -0.5V to give a bit of bias to the tantalum cap. You need a response almost to dc in this part of the circuit as otherwise the EF cancellation is compromised. A 0.1uF cap that Garrett used, giving a high pass response at this point, was not the best.

Eric.

[blobber]

some impressions of my PRO XL500












https://youtu.be/zcRZcBLnDhU

[blobber]

#40
http://www.geotech1.com/forums/showt...ggestion/page2


Hi Blobber (Fred),
Thanks for sharing your layout.
I'm making a waterproof detector to use it in salt water scubadiving.
I have few questions about the motion pi detector :


1st: Do you think IP67 pots would work in salt water ?
2nd: Can you explain few thing about tuning this unit ? I mean, adjust the trimmers on the board.
3rd: I have two coils waiting for a detector (see picture). Which one do you think is the best for this detector (maybe none ???) ?
coils.jpg
I was puzzled the first time i saw the shematic cause the + power is generated by a charge pump on the negative power with NE555 ... It was strange for me, usually, it's the opposite way but waybe i did not see enough schematic ...
Your help would be appreciate.


--------------------------------------------------------------------------------------------------------------




About pot IP67 I can only say, they are dust proof and in my opinion, it means not, that they are water proof.
The trimmer 10k near 78L05 is threshold for audio and 25k near 4538 is discriminate basic adjustment. 10k near T5 is low battery control, Trimmer 100k near 709 is also not critical. Near middle position, you will have the best operation point and detecting range for targets.
As I made this detector in 2004, I had only a simple multimeter and my ears for adjustment. It was very quick to do.


Your coils are looking very interesting, I think both will working good.
Could you give instructions, parameter please, about the left coil?

Fred

[blobber]

Yes, I also was confused, about power supply, but it's working realy
fine. But a good option could be #17 by RS_Phil.
Here is my layout file, with some small corrections.

Fred

motion PI_blobber.zip

[reptooyep]

Hi,
Many thanks for taking time answering me. I love this shematic and it sounds good to hear that it's easy to tune.
One of my first project was the blind squirel pi and it worked pretty good but it had to be tune few times with t°c and battery changes.
For the coil, it's tricky and long to do but it looks awesome. I made 4 of these and the first one was a flop cause i did not find any help on this.
I found the picture on a thread on thunting :
http://www.thunting.com/smf/pi_desig...s-t7657.0.html
Nobody said that once you have done a complete turn, you must shift the start of the second of three notchs in order to change the
Side and cross. It's very hard to explain ...
Let's try..
The circle has 37 notchs interior and exterior.
So, you cut a circle and make marks each (PI.d)/36 and cut the notchs.
I did it with plastic foam and cut everything with a jigsaw.
Lets talk about side A and B.
Lets say that you start int. Side A.
Then you go to the notch +3 ext. Side A
You are now ext. Side B.
Then you go to the int. Side B+3
Etc until you are back to the step before your starting point.
Instead of going a second time into the start point, you should be ext. Side B, you go through Ext side B +3.
And you continu until you have 6 layers in each notch.
Once you have the trick, it's simple... as everything.
If you don't have it, i'll try to make a draw but i'm not sure it helps.
Thanks again for your explanation

[blobber]

When sensitivity pot is set to approximately middle or quarter position, where the unit is working stable, you need no further adjustment in fresh or salt water.
Of course, when you get a target, you have to discriminate at least half, or full, to see if it is rejected. If so, you have a good target.
This could be to do, more comfortable with a switch in your handle. I was thinking about it, but have unfortunately never realized.

[reptooyep]

I though of a switch with fixed resistors to replace the pot. That's what you mean ?

[blobber]

Hi,
Many thanks for taking time answering me. I love this shematic and it sounds good to hear that it's easy to tune.
One of my first project was the blind squirel pi and it worked pretty good but it had to be tune few times with t°c and battery changes.
For the coil, it's tricky and long to do but it looks awesome. I made 4 of these and the first one was a flop cause i did not find any help on this.
I found the picture on a thread on thunting :
http://www.thunting.com/smf/pi_desig...s-t7657.0.html
Nobody said that once you have done a complete turn, you must shift the start of the second of three notchs in order to change the
Side and cross. It's very hard to explain ...
Let's try..
The circle has 37 notchs interior and exterior.
So, you cut a circle and make marks each (PI.d)/36 and cut the notchs.
I did it with plastic foam and cut everything with a jigsaw.
Lets talk about side A and B.
Lets say that you start int. Side A.
Then you go to the notch +3 ext. Side A
You are now ext. Side B.
Then you go to the int. Side B+3
Etc until you are back to the step before your starting point.
Instead of going a second time into the start point, you should be ext. Side B, you go through Ext side B +3.
And you continu until you have 6 layers in each notch.
Once you have the trick, it's simple... as everything.
If you don't have it, i'll try to make a draw but i'm not sure it helps.
Thanks again for your explanation

Thank you, I see there is also a template.
Do you think, the coil gives mor range to targets?

[blobber]

I though of a switch with fixed resistors to replace the pot. That's what you mean ?

Yes correct.

[reptooyep]

Do you think, the coil gives mor range to targets?

I'm not sure of that but it looks amasingly better than a simple flat coil ? No ?
It has less interwinding capacitance. I'll test with xl500

[blobber]

Aha..well my first coil for this detector was similar like this here

http://www.calvin.edu/academic/engin...20Detector.jpg

but only with one wire, and I had a poor target distance.

[6666]

Hi,
Many thanks for taking time answering me. I love this shematic and it sounds good to hear that it's easy to tune.
One of my first project was the blind squirel pi and it worked pretty good but it had to be tune few times with t°c and battery changes.
For the coil, it's tricky and long to do but it looks awesome. I made 4 of these and the first one was a flop cause i did not find any help on this.
I found the picture on a thread on thunting :
http://www.thunting.com/smf/pi_desig...s-t7657.0.html
Nobody said that once you have done a complete turn, you must shift the start of the second of three notchs in order to change the
Side and cross. It's very hard to explain ...
Let's try..
The circle has 37 notchs interior and exterior.
So, you cut a circle and make marks each (PI.d)/36 and cut the notchs.
I did it with plastic foam and cut everything with a jigsaw.
Lets talk about side A and B.
Lets say that you start int. Side A.
Then you go to the notch +3 ext. Side A
You are now ext. Side B.
Then you go to the int. Side B+3
Etc until you are back to the step before your starting point.
Instead of going a second time into the start point, you should be ext. Side B, you go through Ext side B +3.
And you continu until you have 6 layers in each notch.
Once you have the trick, it's simple... as everything.
If you don't have it, i'll try to make a draw but i'm not sure it helps.
Thanks again for your explanation

Are you talking about the Russian spider coil also known as 3DSS, the trick is, after a complete wind move forward one slot have a look here at pics
http://www.geotech1.com/forums/showt...720#post190720