CROSSBOW CLASSIC PI QUESTION

[daverave]

does anyone one have a circuit diagram for this detector or a pcb that i can purchase ???

[Qiaozhi]

does anyone one have a circuit diagram for this detector or a pcb that i can purchase ???

Please contact Sven.

[SVEN1]

Dave I have one PCB left I can spare, will PM you

[timp]

Des anyone have a circuit diagram for the Crossbow Classic PI detector, please?

[kenny444]

Hi Sven is going to order 10 PCB's with a new rev "C" if he can get enough interest.

[SVEN1]

I will duplicate my post since it was not on a Crossbow specific thread and on a Surfmaster Thread.
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The Crossbow is not mentioned on my website at this time, just the Mirage.
The Crossbow was intended as a personal project after seeing the glowing reports of those that bought one of the orig. 12 Crossbows built by George.
Since it was not possible to purchase a built Crossbow, George sent me files etc. to build Rev. B, which was not tested built yet. I took on the project with two others and had 5 PCB's made.
Due to this or that, only one built was completed with good results with difficulty. Remember this is an advanced project like the Hammerhead, if you don't know what your doing............
Anyways, I sidelined the project for 2 years concentrating on the Mirage PI. On my Mirage builders forum for those that bought a PCB from me, a question was posted if I had thought about
ordering some more Crossbow PCB's and giving the project another try. There was enough interest to for a restart and order a min of PCB's. So 6 of us are attempting the build again.
A number of Geotech forum members are on board helping out with this project.
Chris has the first one working with superb results, the rest of us are somewhere along in the build.

Due to the latest posts on Geotech, some other members might be drawn to this project, which is great. For a first project, your better off with building George's Min-Pulse Plus before even
attempting the Crossbow. Right now consider the Crossbow project in Beta-mode.

George just send me Crossbow Rev C Gerber files which corrects Rev. B LED error on the PCB.
For anyone interested in a Rev C PCB, I will have a batch made to order once I reach a min amount of 10.
Due to currency value changes, pricing will be in US dollars.
$13.00 per PCB , plus shipping for up to 4 PCB's to the US $8.50, Europe $11.00
PCB's are of high quality. 2-sided, gold plated traces and pads.
Please PM me if interested.
I do have sub-forum set up with all Crossbow info for those who purchase a PCB from me to help those building the Crossbow.

This is going to be a one time batch group order. Cut-off date for placing an order will be March 15th.
I have already reservations for 6 boards, so min. board order amount will easily be reached. My PCB supplier is quick, 1 week turn around after
order is placed and they are at my doorstep.

I accept Paypal using the Send Money to Friends and Family Gift option only.

[Mega B]

Just seen the video Chris has made on his Crossbow build,the depth does seem to pretty good with that 10'' coil.

[SVEN1]

Just seen the video Chris has made on his Crossbow build,the depth does seem to pretty good with that 10'' coil.

Pretty good start...................so far........
Just remember, your the cause of all this....LOL, had it not been fgor our first contact with each other regarding the Crossbow and you knowing George. The Crossbow project would probaly would have remained stuffed in a dark closet and forgotten.
Happy Hunting

[chrisw]

Hi Guys,
Regarding the Crossbow build.
Where is everyone fitting the damping resistor? In my first build box I have the damping resistor inside the box on the back of the coil socket. But if I attach a different coil which may need a different damping resistor it means taking the box apart to change the value.

If I put the resistor inside the plug there isnt enough room because the coax is a little thick. So I was wondering if everyone just sets this resistor for one coil and then just ignore the discrepancies if fitting other coils? Or is everyone putting the resistors inside the coil housing? Thats ok for homebuilt coils but what about bought coils? Open to suggestions.

Chris

[Skippy]

If fitting a resistor in the plug is a problem because of the size of the resistor, might it be possible to fit a resistor that's the highest value of what your coils need, inside the control-box, then just add a parallel resistor in the coil plug. This will be lower power requirement, so can be smaller.
EG. coils need 300, 320, 390 Ohms. Put 390 in the box, then in the '320' coil plug put 1K8, in the '300' coil plug, fit 1K3.

[chrisw]

The problem I seem to be having is the coax is 6mm diameter, then I have a few links because they are mono coils, then getting a resistor in there without things shorting. Its a 5 pin plug so terminals are small and the terminals also move about, maybe I should look for better quality plugs, might help.

[multieagle]

Hi Chris, I just fasten it in with the pcb coil connector, as imaged below. It seems to work okay for me. I'm not familiar with technical parameters relating to damping resistors. Why would you require additional resistors in the coil and pcb plugs if one is installed at the board? Image attached.

Crossbow video with DR as described above: https://www.youtube.com/watch?v=ChfS61gS9YE

I might add the DR was changed since this video with resulting increase in depth.

[chrisw]

Hi Gord,
The different coils I have made are all 500uH but they all seem to need a different value damping resisitor, maybe the capacitance is a little different. But I like to set the DR so that the coil is almost ringing and is not being over damped. It seems to make them more sensitive. Al the moment mine is inside the box, but I want to change this so I dont have to keep opening the box up.

[kenny444]

Hello Chris (Not very well here) This popped up in my mail box, I do not know how current it is. I planned my DR in the search coil so the DR and coil are a pair, A different coil then has its own DR, built in. I think that is the same as the Teknetics T2 which has a sealed access on the coil housing. (I may be wrong), Further, I have done nothing with the boards or coils recently as I am up and down, mostly down.

[chrisw]

Hi Ken,
The reason I put the DR in the box originally was so when I had made new boards I could then adjust the DR and use the coils on different boards.
I found that a coil which was ok on one board would ring on another board, so needed adjustment. I dont know why.
Hope you feel better soon Ken.