'KROT2-XM' (mole), new project Xmega32

[Geo]

Hi wm6.
Thanks for your time.
As i see at schematic R1 and R2 are not necessary to program the controler. If so then you can ship it.
What about your new coil???

Regards

[WM6]

Hi Geo

I wish to complete this DIP version of board and test it, to not need to build two and then find, that maybe something is wrong.
There are some differences between this DIP board and schematic, hope nothing fatal.
Over the weekend I will be (as usual in another town) not at home and away from my lab, so this project will continue at Monday.

My version of KROT-2 coil need some potting finalization, but all is tuned and fixed and coil is ready for tests.
In fact I tested it with Andrey's SMD version of board and it works satisfactory - more than 30cm detecting distance on coins in air.
Probably due that I use enameled aluminum wire instead of copper wire, coil setting procedure is not always repeatable with same results.
KROT-2 do not balance this coil at same frequency as it was build and tuned.
I tuned it exactly to 8kHz but KROT set it about 100kHz higher or sometimes lower.
Alu has higher resistivity and I need to bridge 5E TX resistor to got enough coil current (70 to 90mA).
Due resistance Q-factor of TX coil go to halve in comparison to copper wired coil (9 instead of 24) this can imply in KROT-2 Coil setting procedure.
But thanks to Alu wire coil is light.
TX tank capacitor of 330nF is here build in coil, so serial TX C on board should be omitted at coil connection.



I will continue with this project work on Monday.

[Geo]

Ok, i am waiting for even better results.

Regards

[Wiltran]

Krot2

I built Geo's DIP board version, and it works. But Geo you forgot to put a provision for RX cap. I know its supposed to work without it but I just soldered a cap on the bottom of board. I like the way this MD gives different tones for different metals. As usual, the devil is in the coil, and in this one the MP sets the TX freq.and I'm having trouble getting the TX coil resonant. Im running it on 4 AAA alkalines, but I want to use 2 lithium batteries. Anyone have any thoughts on TX1, TX2 coil connections? WM6, aluminum wire sounds like a great idea but I think I would have a hard time getting a good connection soldering etc.

[WM6]

WM6, aluminum wire sounds like a great idea but I think I would have a hard time getting a good connection soldering etc.

In fact i have so called ECCA wire, mean Enameled Copper Clad Aluminum wire of 0.25mm. Due copper plated wire there is no problem for soldering even without removing varnish enamel. For TX coil I use two of such wire in parallel windings.

If one have enameled Alu wire (not copper plated), it can be soldered too, using, par example, "Solder-It" Aluminum / Pot Metal solder paste. Varnish enameling need to be removed first.

[Geo]

DIP pcb was not drawn by me but from the author...
I only made a check and constructed 3..4 pieces: Lol:.

[Wiltran]

DIP pcb was not drawn by me but from the author...
I only made a check and constructed 3..4 pieces: Lol:.

Sorry Geo, well at least we know the board works.

[Geo]

I built Geo's DIP board version, and it works. But Geo you forgot to put a provision for RX cap. I know its supposed to work without it but I just soldered a cap on the bottom of board. I like the way this MD gives different tones for different metals. As usual, the devil is in the coil, and in this one the MP sets the TX freq.and I'm having trouble getting the TX coil resonant. Im running it on 4 AAA alkalines, but I want to use 2 lithium batteries. Anyone have any thoughts on TX1, TX2 coil connections? WM6, aluminum wire sounds like a great idea but I think I would have a hard time getting a good connection soldering etc.

How did you connect the coil??? pin 8 and gnd or pin8 and pin5 (MC34119)??
Also for WM6 ... did you try both connections??? if yes who are the results???

[Wiltran]

I connected at R3 and ground. I dont have a completed MD, I only have tested it on the bench with a crude DD coil. I wonder if this would work with a Dbowers style concentric coil?

[WM6]

Also for WM6 ... did you try both connections??? if yes who are the results???

Not yet. Only over R3 (MD3030 CC coil) and without R3 (my Alu DD coil).

[Geo]

I connected at R3 and ground. I dont have a completed MD, I only have tested it on the bench with a crude DD coil. I wonder if this would work with a Dbowers style concentric coil?

I believe that if you keep the details of coil near to these that the author says.... then there is not any problem. I have many coils to try....

[Geo]

Not yet. Only over R3 (MD3030 CC coil) and without R3 (my Alu DD coil).

If you ""speak"" with the author please ask him.

[WM6]

If you ""speak"" with the author please ask him.

Probably I should test those "spare" TX connection too.

Namely main problem occurred with present authors SMD board was inconsistency in settings results at the settings repetitions on KROT-2 restarting.

OK, I know that both of my coils (MD-3030 coil and Alu coil) are not ideal per electrical characteristics, but author say that it should be balanced anyway.
Coils can be balanced, but not consistent, every-time at the same values. I will make one more ideal coil out of copper wire.

For now I am interested how our DIP version will manage both coils, if board will started as should.

What I mean with "inconsistency".
In first line how in settings procedure detector is balanced to coil resonance.
For now in 10 restarted procedure with my Alu coil tuned at 8kHz I got say 6x balanced at 8.1kHz, 2x at 7.9kHz, 1x at 7.7kHz and 1x at 8.3kHz or so.
With MD-3030 coil such frequency dissipation in coil balancing is even more greater (I bother two weeks with this coil but cannot find nothing wrong on connection lines or with coil itself).
I wish to solve or explain this issue soon.

[Tepco]

No problem at all with coil auto-tuning. It just monitor TX current consumption, searching for maximum, if it miss 1 or 3%, no big deal. Especially with alu wire coil and lower Q, or higher resistance MD3030 coil, you can always tune it manually.

[Tepco]

Forgot to mention, use another output in “bridge” mode to increase TX current for low Q coil.