Sniffer xr71 / delta pulse version

[johnyp]

Hi to all, some days ago I bought a sniffer xr71 / delta pulse version that works only in auto mode and doesn't have the option for manual mode. Bought the PCB I mean. After some tests with a day coil of 30cm at 240mh and 1.8 ohm I get a really bad sensitivity. Anyone has ever built this one or has any tips to share would be really appreciated. Also I want to construct a 50x50cm coil using utp cable. Does all utp cables are ok? How many turns should I go for, what resistance should I expect and about what inductance? Thank you very much.





Last image is the coil I made.

[jezz]

I bought a Sniffer XR71/Delta Pulse version off Ebay from Turkey and the board performance is terrible. Tried several coil configs and not much luck. Hope you get yours to work.
Good Luck

[johnyp]

I also bought it from Turkey. Tested some coils but sensitivity is just tragic. Anyone has the schematic of the specific board? Also does anyone knows how can I put a manual switch and not use the auto mode! Finally would appreciate some info on making a coil of 50x50cm using 0.5mm wires stripped from a utp cable. Tried the solution with the utp but can not get resistance above 1 ohm for 32 turns. Thank you

[kt315]

your trouble is one and too famous - unright enclosure shielding or full lack of it, basing on misunderstanding how to do that right.

[johnyp]

If I remember correctly kt315 you had wrote some lines about shielding... Will try to find them yes. Besides the shielding can you help with the coil construction? What wire to use for a 50cm square coil, how many turns and what resistance would be approximately? Also saw that this PCB has dumping resistor of 2.2k! You think it's ok? Any tips would be great. Thank you very much

[kt315]

ok. let to see pics of your construction first. try to create an album and upload your pics in it.

[johnyp]

Here are some photos of the box and two test coils.
The one with the utp is 4 turns and doesn't work at all and the other one is made from a copper wire 0.5mm with 30 turns that measures 1.2ohm at about 270mah.

With the second one I can detect the tool in photo at about 10cm only.

I also tested an original xr71 coil circular 60cm rating at 3ohm at about 970mah.
With that one can detect a PC CDROM unit at about 50cm.

I thing this is no good for this machine!

Probably I am doing something wrong here.

Thanks in advance.

[johnyp]

Well, has anyone built that same machine? I mean the specific PCB version one?
Thank you

[jezz]

Hi,
I have the same board as you I think and it has terrible performance. . The damping resistor on mine is 2.2k. I tried a 1k as I have seen a schematic with that value and one with a 680 ohm value but it made my board perform worse.
As far as manual/auto mode you ask about, when you hold in the reset/retune or whatever you want to call it button for a couple of seconds the machine goes into auto mode.
If you do not touch the button after turning on the machine you can adjust it for manual mode. That is how my board is anyway and it is from Turkey.

I cannot tell from your pictures how you have wound your coil - You should have more resistance with 32 turns than you have - hard to explain but if you start with a blue wire on one end then other end connects to say a green wire and other end of green to brown wire and so on until you end with one wire on each end of loop. If using FTP/Cat5 don't separate pairs. Coil should be one continuous loop of wire.

I think boards have problems as I have built 2 other PI's and coils and work great but this board likes nothing. Maybe bad value part or something in it. I asked seller for schematic and he emailed me 2 wrong ones and then nothing more from him.
Sorry if not much help

[jezz]

Also the "signal" and "sens" pots do absolutely nothing on my board no matter where they are set. Maybe that is where the problem is as sensitivity pot does nothing,tried new pots but still same.

[kt315]

why noise? why signal? what the signal? from what signal? where noise? from what noise?
the hallucinations from mushrooms is your board (((((((((((((((((((((((((((

[jezz]

Hey KT315,
Don't know, that is how board is labeled.
Says noise is for power regulation and signal is for rejection of small objects, but signal pot does nothing.
Board was made by someone on mushrooms I think

[jezz]

Picture

[jezz]

picture

[johnyp]

Same thing here also, noise pot is the power and works, looked it with oscilloscope, noise seems to do something as it can reject small irons but lowers the sensitivity. Sens pot does nothing to me also! Doesn't anyone knows where to find schematic of that board? BTW were from Turkey you bought it from? A guy called Mehmet?

Let's see what we can do with this board!

Thank you.