The Crossbow Classic PI

[keith777]

Hi guys.

i have recently bought a Crossbow Classic PI machine. i was wondering if anyone could give me any good tips/advice on using it. theres not really any videos out there of people using them.

thanks in advance.......

[SVEN1]

Did you get the manual?

Is this your first PI?

George can help you. He built it http://www.geotech1.com/forums/member.php?619-Qiaozhi

[Qiaozhi]

Hi guys.

i have recently bought a Crossbow Classic PI machine. i was wondering if anyone could give me any good tips/advice on using it. theres not really any videos out there of people using them.

thanks in advance.......

Is this the Crossbow PI that was sold recently on UK eBay?

If so, it uses a PCB that was supplied by Sven, and I believe it has been slightly modified. As far as I could tell from the eBay photos, the battery check circuit and the internal battery charger have been removed. The NiMH battery pack has been replaced by a Li-ion pack, and a suitable external charger. Also, the MOSFET has been changed from an IRF740 to an IRF840, and the electronics are housed in a different enclosure. There may be other changes, but these are not immediately evident from the photos.

I can send you an original User Manual by email if you wish.

[keith777]

Is this the Crossbow PI that was sold recently on UK eBay?

If so, it uses a PCB that was supplied by Sven, and I believe it has been slightly modified. As far as I could tell from the eBay photos, the battery check circuit and the internal battery charger have been removed. The NiMH battery pack has been replaced by a Li-ion pack, and a suitable external charger. Also, the MOSFET has been changed from an IRF740 to an IRF840, and the electronics are housed in a different enclosure. There may be other changes, but these are not immediately evident from the photos.

I can send you an original User Manual by email if you wish.

yes thats the one.
yes i did get a manual with it. i have not used a PI before. i have always wanted one. i have recently been trying to put a Sniffer XR-71 DELTA PULSE together as a project, but i am not having much luck with it.

[Qiaozhi]

yes thats the one.
yes i did get a manual with it. i have not used a PI before. i have always wanted one. i have recently been trying to put a Sniffer XR-71 DELTA PULSE together as a project, but i am not having much luck with it.

You may want to read this ->
http://www.nuggetshooter.com/article...Idetector.html

[alcapone]

Can you tell me what effect changing irf740 to order840 has on the crossbow. Thanks.

[eclipse]

Absolutely no effect. IRF840 will run hotter, otherwise there shuldn't be any significant difference.

[alcapone]

Thanks

[Qiaozhi]

Can you tell me what effect changing irf740 to order840 has on the crossbow. Thanks.

IRF740 has a breakdown voltage of 400V, whereas the IRF840 is 500V.
The higher breakdown voltage will allow the detector to sample slightly earlier, but the advantage will be very small on the Crossbow. This is because it uses a single-stage preamp.

[alcapone]

Thanks

[Wahyu]

You may want to read this ->
http://www.nuggetshooter.com/article...Idetector.html

Hello Qiaozhi, i'm confuse about this;

As for a PI, the pulse rate or pulses per second (pps) refers to the number of high current pulses that occur over the time specified. Rates vary from a few hundred to several thousand per second: Generally, more pulses allow for a little better averaging and thus a little better signal to noise ratio. However, a detector will have a tendency to consume more current with a higher pulse rate. A faster pulse rate doesn't mean a detector will detect small gold better. In fact, it is quite easy to build a PI that has a very low pulse repetition rate (PPS) that is very sensitive to very small gold while designing a PI with a high PPS that is not sensitive to small nuggets.

[Qiaozhi]

Hello Qiaozhi, i'm confuse about this;

This just means that the pulse repetition rate is not the main factor for detecting small gold. The most important thing is to reduce the decay time of the coil current so that you can sample before the target signal has disappeared.

[green]

This just means that the pulse repetition rate is not the main factor for detecting small gold. The most important thing is to reduce the decay time of the coil current so that you can sample before the target signal has disappeared.

An example changing target delay time I posted awhile back, sampling sooner. The lower the target TC the greater the detection distance difference with changing delay time. Increasing sample rate reduces noise and increases average coil current. My tests, I haven't seen a big advantage increasing sample rate from 1000pps to 3000ps or 5000pps. Some have seen an improvement.

(Chart)4 and 10 grain are gold nuggets

[TowySalmon]

Qiaozhi, I am awaiting delivery of a recently bought Crossbow. It is one of the originals.
Is it please possible for you to provide me with a user manual? Or could anyone kindly direct me to where I may download one from.

Can anyone help with suggestions of compatible coils please? I have read somewhere that the following can be used:
Detech 18” Mono
14”x10” brand not known

Thank you.
PS, I am unable to send PMs as access is denied when I click on someones name. E.g I tried to PM Qiaozhi but failed.

[keith777]

Hi TowySalmon

here is the instructions that i got with my Crossbow Classic PI.