Cooplanar coils - tune

[mnichu]

Hi,
I made cooplanar coil and I try to tune it. On fig.1 (attached files) are my coils in form of plaster. On fig. 2 is the siglnal from generator and the signal from RX-coil.
(sinusoudal wave is from RX with amplitude 50mV/DIV;second signal is my generator from uC -5V/DIV- which go through two transistors to TX coil; TIME/DIV=50us).I added and removed some turns of wire to the bucking coil without success - amplitude on RX coil is always above 100mV. Best result which I had is on fig.2 I tune my coils with capacitators on TX and RX side. There is no metal near my coils.
Can anyone tell me what is wrong?
thanks a lot for help
Michal

[Unregistered]

coil

hallo
your wrong-you build a transformer.
because that thas not work.

the big coil mast be tx.
in the center of the head mast be rx coil.
it s diameter 0.5 from tx.
directly above rx is the third coil for tuning zero.
it s tuns 1/4 from tx .this coil is conected in series
with tx but in opozite faze.

barossov
best regards
[email protected]

[Unregistered]

For me, i think you not wrong but i not have all the answer for it

I had build the bandidoII this winter with the rod,box,searchead,etc...
I had make the same coplanar coil with a buking coil (from TX)over the RX coil
and i obtain the same results on scope (100mv on rx)with the same degre of phase.

With or without shield on coils, it's the same thing and i use a 2 pairs individualy shielded cable.
Presently, i'm work on a protoboard with the classic3 shematic and a DD coil configuration at 6.5Khz aprox. and the same result appen.

My detector (BandidoII circuit) work ! but i can't adjust the ground balance correctly (because i not respect the TX frequency for the value of timing components) i will try to duild a new DD coil with the correct numbers of turn(this time!!) 10Khz!!

I am not a king of electronic but that's my experience to date.
I hope this can help you a little bit!

J.F. Langevin
(P.S. excuse me for the bad english ,i write to you with a dictionnary beside me)

[Unregistered]

for me the circuit is mistaken!