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

[OCBSlimz]

Disconnect coil, turn on, what RX reading you got ?

[reptooyep]

Hi,
I made a nex RX coil (155 turns of 0.15mm L=15.9mH, R=106ohm).
I use for TX circuit 249nF for my 45 turns of 0.4mm (1.06mH, 3.5ohm).
The coil nulling is now easy, i can reach a 10mv A/C and RX lags TX of 20°.
With my coil nulled (Oscilloscope view : )
, i still have 500mv displayed for RX. I heard it should be near ZERO ??
My settings are :

Firmware : K2 GAIN SGOLD
Frequency : 10022HZ
RX : 519mV
Gain : 2
Power : 67mA (Maximum)
Is it normal ? I did the tuning as the TGSL project, is it the same principle for KROT project ?

Here are some pictures of my board :

OCBSLIMZ : Have you done your coils ?

Any help would be appeciate, i'n not far from gold rush ...

[timekiller]

...Power : 67mA (Maximum)
If this value is obtained after starting automatic setting for Tx frequency , I -Tx can be increased by connecting in 1-3 and reduce R4 .

[reptooyep]

My TX is already connected to 1-3 and R4 is measured at 5 ohms. My coil resistance is 3.5 ohm.
Is there a "limit" value i shouldn't go below ?
I'll try with 2 ohms to see the difference.

[timekiller]

My R4 - 1 ohm. Set R5 low value , approximately 15 k or 10k . Try set - turbo mode and M - meandre not S - sinus .

[OCBSlimz]

Hi,
I made a nex RX coil (155 turns of 0.15mm L=15.9mH, R=106ohm).
I use for TX circuit 249nF for my 45 turns of 0.4mm (1.06mH, 3.5ohm).
The coil nulling is now easy, i can reach a 10mv A/C and RX lags TX of 20°.
With my coil nulled (Oscilloscope view : [ATTACH]36073[/ATTACH])
, i still have 500mv displayed for RX. I heard it should be near ZERO ??
My settings are :

Firmware : K2 GAIN SGOLD
Frequency : 10022HZ
RX : 519mV
Gain : 2
Power : 67mA (Maximum)
Is it normal ? I did the tuning as the TGSL project, is it the same principle for KROT project ?

Here are some pictures of my board : [ATTACH]36074[/ATTACH] [ATTACH]36075[/ATTACH]

OCBSLIMZ : Have you done your coils ?

Any help would be appeciate, i'n not far from gold rush ...

My RX is around 350 without the coil .... Maybe the firmware? ?

[timekiller]

My TX is already connected to 1-3 and R4 is measured at 5 ohms. My coil resistance is 3.5 ohm.
Is there a "limit" value i shouldn't go below ?
I'll try with 2 ohms to see the difference.

try another mc34119

[OCBSlimz]

Hi guys. Had another go over the holidays and found the problem with the high RX gain. I changed the 7092 with a mcp633 and it is now at 2hz.

I would like to test a coil with this. Has anybody tried a garrett euroace coil ? I have one spare and would like to test with this. I'm a noob when it comes to coil winding. Could anybody give me a diagram to wire it up ???? Thanks.

[Virdi_248]

After failing for lack of information building KROT 1 KROT2 I want to try to build a modified version DIP board.
There equivalent ATMEGA32 chip dip 44 pin dip?

[OCBSlimz]

No. Use atxmega32a-au.

[reptooyep]

Hi,
The SMD version gives me too much troubles to tune anything. I get rid of it for the moment.
I'm making the DIP version (thanks to OCBSLIM for the board).
Without coil, i have 16mv (diPlayed). On pin 1 and 44, i can read 1.666v which seems correct.
I use 4ohm for R3 and 1kohm for R8 (i don't know how to choose this value cause i tryed few without any change)
When i plug the coil, i'm not able to read less than 3500mv).
For the TX cap, i use 300nF and i tune it to 8300hz. I also tryed with 200nF ant 10000hz but i can't reach a reasonable value for RX.
Any advice would be great

[reptooyep]

I tryed differents RX coils :
22.5mH (200 turns)
15,7mH (165 turns)
11.7mH (142 turns)

For each coil, i tryed several C0 values an frequencies (8khz, 10khz and 13.5khz).
I can't have a RX signal less than 3500mv.
Without RX, i read 16mv.
Could someone give me his working coil specifications (gauge, nb of turns and inductance).

One more question : i read that RX should have a frequency of 2khz less than TX but how can you be sure of that ?

[Koala]

Can't help with the first part of the question but to test the RX it's easy to connect it to TX temporary and measure the frequency. Same method I use. Better than measuring its inductance with a meter of unknown accrucy.

[reptooyep]

I understand but if you plug the RX coil to the TX circuit, you will never have the 2khz difference cause rhe RX inductance iw 10 times more than the TX one.

[Koala]

I understand but if you plug the RX coil to the TX circuit, you will never have the 2khz difference cause rhe RX inductance iw 10 times more than the TX one.

inductance is different but so is the parallel capacitors. Does it not work out. I am no good with maths ?????




Ahh is see. Just had a look at the schematics. Not easy to test in circuit. Especially with the layout and on board capacitors.


Data for the DD coil frequency ~ 8.0 (10.0) kHz, diameter of 25-30 cm
Number of turns of the transmitting TX ~ 45 turns of wire 0.4-0.5mm C1 = 0.3 (0.22) microfarads
Number of turns of the receiving RX ~ 200 turns of wire 0.15-0.22 mm C0 = 0.022 (0.015) microfarads
Is the data posted over on thunting.com


Not being able to null a DD closely is normally down to the shapes of the TX and RX being slightly different. Still 3 volts is a lot to be out.