Garrett (pulse) XL 500

[Ken H.]

I have a Garrett Sea Hunter to restore (hopefully for my own use)

Was mildly surprised to see that Garrett has ground the labels off six of the IC's on the board. Don't know if the photo will show it or not.

[Seras]

Re: Garrett (pulse) XL 500

nice photo

[Henry (OR)]

Re: Garrett (pulse) XL 500

Garrett was great for grinding the surface of the ICs used to keep someone from copying their design and probably keep the competition down. I think they should give the schemtaics on them, but they have to be 20 years old before they will. The excuse is there might be something in a circuit that may give someone the key to a current model. Bunk! Its just to make sure that the technology is "too old" to do anything with. That is the truth as I have investigated this myself at Garrett. I think it is rather petty to be that way. Compass is even worse in that they won't release any schematics even for their first machine made in 1970 to keep the repair competition down to 2 places. Them and Keiths' repair shop. They are just cornering the market on repairs is all it is. Creating a small monopoly is just whats going on. Either you do business with them or not at all. What ever happened to "Free Enterprise"? With over 285 million people in this great land, you mean to tell me there is no room for another shop to do repairs of for someone to redesign something to be even better than originally so? Even to make aftermarket products for some of them is difficult as everything is a "Big Secret". They should be very glad to help out with a company that helps keeps those machines they make and made out in the field. Maybe one of them will read this and get the hint! Just some of the nonsense I have had to deal with. I thought I would share this info with you all.....................H

[kt315]

ok. all info on the matter XL-500 your info will be greatly appreciated.

[kt315]

Although the schematic is similar, it is not that of the Garrett XL500. It is a general circuit arrangement that was used (and copied) with modifications in various land and underwater detectors in the 1980's, but originated in my Irish company, Location Technology Ltd. The adaptation of this circuit was a project we did for Charles Garrett and was their first P.I. detector. It replaced the VLF unit they previously had for water hunting.

Where your circuit originated I do not know, but various things have been changed which make it rather different from the XL500, but it looks sound and should work well. It could benefit from a few upgrades though; initially, replace the 2N3055 with a Mosfet such as the IRF740 and the 709 with a 5534. The 5534 does not need the 3.3pf and 10pf capacitors to keep it stable.

Eric.

...........

[kt315]

Hi Fred,
Yes, that corresponds with the proper schematic.

The LM358 is a dual audio oscillator which Garrett added to give a warbling effect to the audio. Garrett called it 'mellotone'. On my official Garrett schematic the coil damping resistor was 150R rather than 1K0. 150R does seem a bit overdamped though and I would put 270R as nearer the optimum. If you make your own coils this value needs to be matched to the coil characteristics. For the 3140 and 741 you can substitute TL061 or TL062 for a dual package to run both functions. The 4016 is a quad switch which switches the meter from signal indication to battery voltage indication. 555 can now be Cmos type.
Your unit has a high pass filter which is the 3rd 324 stage where you have a 0.47uF capacitor on the input. This gives what is called a dynamic, motion mode, or self zeroing response. The XL500 does not have this.

Looking at the Minipulse Plus thread, I would think this would be a very good basis for a waterproof detector. Maybe it has been already suggested as I have not looked at all the posts. This has a better receiver front end and lots of other updates on a very similar circuit arrangement. It also has the high pass filter mentioned above.

Eric.

....

[homefire]

Does this help ?


xl5ooschematic2.zip


Forgot one.

[blobber]

That's great thankyou

[ripsdevala]

Pi with target elimination? Is this real? Blobber make one of this work, the last barracuda I built is love trash so much.

[blobber]

Yes, that's right, but unfortunately the detector reject only the good things. But I used it without discrimination until I get a target, then I turned the disc pot half or full. So you can at least decide, if you want to dig or not. But it is not very correct. Discrimination of IB detectors are much more better and easy to use.

[ripsdevala]

[blobber]

As I already said in this thread here,


http://www.geotech1.com/forums/showt...ild-suggestion


in 2004 I have made a similar version of this Garrett (pulse) XL 500, it was my first metal detector,
also waterproof and the unit is working until today (okay, please forgive my mistake last week! now all is
dry and working, but not yet waterproof again)
After this detector, I have made also different PI detectors, but this one is in any case my favorite,
because he is very stable (when sens. is not to high of course), you not need to adjust.
All my other PI's are using the click sound, I don't like this sound.
My version of the XL 500 has a similar sound, as a IB detector, in my opinion it's more pleasent.
Also the performance is not too bad. (in air 24 cm, 1 Euro, 21 cm coil, 20 turns)

[blobber]

I am in progress with a sprint layout file, taken from my original terrible hand drawn layout file from 2004. At this time, I had no knowledge about computer or any electronic design programs.
Later I can post here my file, if someone is interested, maybe next week I am finished

[ripsdevala]

As I already said in this thread here,


http://www.geotech1.com/forums/showt...ild-suggestion

To the scene ......

[blobber]

Well, I am finished with my new sprint layout 5 file, from my similar version of the Garrett XL-500 Pulse,
which I have builded in 2004.
A short video you can see here

https://www.youtube.com/watch?v=9z1rWMOpB28&feature=youtu.be

The new file corresponds to my crazy hand drawn layout files, which you can also find in the folder.
The values of all components are correct also Transistor T2 is what I had used, I hope there are no mistake, two times checked.
PCB size is 46 x 115 mm. Sorry, there are some long wire bridges.

PI_blobber.zip