Inside the TX-2002 pinpointer

[mr.sneezy]

Hi guys,

Hey nice to see the schematic and the clone circuit board made up, makes me feel better about the time it took to document all the parts on mine.

I've been very happy with the way mine works now, I'll stopped tinkering and done treasure hunting instead.
The modified (coil) pin pointer is finding stuff for me. Battery life is good so far, I've not changed it after about 6-7 hours of fossicking on beaches and old ruins. The sensitivity adjustment seems good, set once and forget it. I removed the white LED I don't treasure hunt in the dark. My main detector is an X-terra 705.

Thought I post a snap of the loot
No treasure yet, but had a good time looking.

Cheers,
Martin

[kt315]

Eddy writes on his webpage he has repeated the pcb and it is working good.

[sinclairuser]

thanks eddy, these are quite good once tweaked, its the coils that are off.

[Eddy71]

I draw schematic from PCB:

http://smartelectronix.biz/publ/kak_ja_srisoval_kitajskij_pinpointer_karmannyj_metalloiskatel_tkh2002/1-1-0-48

[miliciano]

I think factory is talking about COMPLETE units , not only the board , price in aliexpress of one TX is 14,54€.

[kt315]

...

The price within 50pcs will be 11.5 USD EXW Shanghai.
----
From:
Date: 2014-02-13 21:19
To: evan
Subject: Re: hello
I believe you are real factory. let me know your price for:
- 5 pcs
-10 pcs
-20 pcs

[kt315]

got a response from the china manufacturer. now ask him a price on 5 10 20 pcs of the boards.

evan [email protected]

We are the real factory . How many pcs do you want to buy ?
----------------
Date: 2014-02-09 03:31
To: evan
Subject: hello
Hello,

Happy new year!
I see your link at pcb... and concluded to ask you...
can you give a schematic on this pinpointer for a repair? can you sell
a batch of bare/blank PCBs on this detector?

best regards

Anatolij

[miliciano]

Thank you mr.sneezy , I have one of this TX2002 (a GT2002) to test your mod.
I used 0,60 mm wire on 10x100mm ferrite and get best results with 60 turns 45.5 khz: face coin 45mm side coin 25-30mm.

Now it is a bit more usefull , will test today on field.

[sinclairuser]

well done mate, i bet those missing components were more or less what you have added, its the only thing that makes sense there.
i see the coil didn't need to be as wound or as complex as it was, i think its obvious that they use pre wound radio ferrites, and just bung anything in probably the cheapest option, well some on here have been looking for a pinpointer project, and now this is as good as any if converted to surface mount it could be even better, but this will probably be igrored in favour of trying to "reinvent the wheel", at least thats what usually happens round here.

[mr.sneezy]

Last bits

Two more (last ?) images of the improvement project.
The unit is actually now a useful tool. I tried it out in the garden and found all sorts of childrens toys (like Matchbox cars) buried under the top inch or two. Also found small items clothes peg springs no problem. So it seems to be ready to try out on a beach or country ruin now.

On my table top $1 coin test with the final coil I get 60mm face-on and 40mm edge-on (to the probe tip). This is a massive improvement from the useless detection 'range' out of the box. I'm happy with that for now, and the unit is worth the $30 I paid for it (LOL, 10 hours of tuning later).

The final winding for anyone else interested is a 100mm ferrite with 60 turns of 0.5mm diameter wire, wound 8mm from the end. The main board circuit is unchanged from original.

My last bit of tinkering was to fit a Haptic device and load the driving components. I used a vibrator from an old Huawei mobile phone. The vibrator in that one is flat round device that looks like a coin cell but isn't.
I used a BC549 transistor (fitted backwards to the silkscreen outline), a 1k drive resistor (R18 ) and a 10k pull down (R19) and a 1N4148 across the motor (D10). There is also a load resistor (R20) to drop the 9V down to about 3V across the haptic (or it might burn out). I found 62 ohms worked for my device. The setup works quite well.

[sinclairuser]

hi sneezy, before i got a whites bullseye pinpointer, i built my own out of one of those velleman kits, the coil for that was a ferrite and it was crap, so i experimented with winding coils, my favourite was not wound on a ferrite but a pole winder, like this,.
dont know if you get them down there or not, your supposed to wind your float rigs on them for fishing, anyway it was just the right size to fit into 15mm pvc pipe, and was wound like an elongated normal coil longways it was very directional which for a pointer i found desireable, i made two like that one without and one with ferrite glued inside and the wire wound around it, obviously the ferrite takes less windings but the ferrite less one wound with 0.5mm mag wire simply worked best.

[mr.sneezy]

The OEM coil

I've done a bit of playing about with the TX-2002 this weekend (another very hot one here).
I removed the original ferrite coil from the pointer. It turns out that the coil was glued in with hot-melt, and putting the pointer in freshly boiled water for a minute or so loosened it up a bit. Pulling on the two wires slowly got it out, well sort of. Half came out, half stayed in To get the second stuck bit out I drilled a 3mm hole in the pointers tip and pushed it out with a stiff wire (heated it again in boiling water first).

So it is the end of that coil as I suspected it might be. The ferrite was broken just below the middle. I'm not sure when this might have been broken, when new, when I tried bumping the coil free, when I levered on it with a screwdriver, when aliens broke into my shed and tampered with it, I dunno.
One small bit of news though is that it was approximately 160 turns of wire on a 100mm ferrite.


Since then I've reloaded the components back on to the TX-2002 PCB (with all new resistors and diodes), and then tested it by rewinding the 62 turns of 0.5mm wire coil onto the OEM ferrite (the longer broken piece of it).
With the OEM ferrite it's not as sensitive as my first ferrite (the 180mm long one) perhaps about 60% as good. The OEM ferrite might be inferior or too short now. I need to buy some more 0.5mm wire to continue as the bit I have has been used too many times. I noticed on the CRO display that the new coil generates a higher frequency than the old test coil, and the coil voltage is only 4V P-P, so I'm going to measure the L value next week before making another coil/coils for testing.

Also need to rat out a vibrator from an old phone and fit the components for that option.
Martin

[Qiaozhi]

Copying a whole book would be problematic, of course, but copying a chapter for educational purposes is something else.

If it's for your own education, then that's ok. But copying a chapter to send to someone else is not ok.

Glad you like the book!

[Davor]

Well, that also depends. Fair use (act) allows copying a part of a copyrighted material for non-commercial purposes. Educational, e.g. DIY purposes are well within the bounds. So in fact it would be OK if a schematic is posted - for educational purposes.
Copying a whole book would be problematic, of course, but copying a chapter for educational purposes is something else.

Personally I like my copy of ITMD very much, and I don't intend to provide any copies of any parts as long as the book is in circulation, and the very authors are here on this forum, and willing to help.

[Qiaozhi]

: Nono:: Nono:
as you say, I wonder?

Inside the METAL DETECTOR is copyrighted, so KT315 is correct in not sending you a scanned image.

If you wish to obtain a copy of ITMD, then please go here and order one ->
Inside the METAL DETECTOR - Published September 2012