Wanted "ADMIRAL"

[Carl-NC]

Admiral should be very tolerant of different RX coils. Smaller inductance means fewer turns which will reduce target sensitivity but it also reduces ground & EMI signals so SNR doesn't change much. You can restore sensitivity by increasing the preamp gain.

[bonchev2]

Thanks for the answers. I ask because I'm making a new one. bigger coil
DD 33 cm for the Admiral and I want to get it right. Today I wound the windings Tx 1mH R-2.8 ohms, 0.47mm & Rx 11.2mH R-38 ohms 0.23mm.I'm worried that the resistance of the Rx is 38 ohms.
At first look the device works properly, the frequency changed from 8.4kH to 8kH and the volts of the Tx went from 18v to 20v.

Do you think i need to reduce the windings of the Rx to lower the resistance and the induction respectively or leave it like that? Rx-132 windings.

[Carl-NC]

38 ohms should not be a problem. The RX coil should not affect the TX frequency or amplitude.

[Zinou]

Hi, I found the same frequency of the coil (Tx: 8.5khz ) on Rx, I changed the value of the capacitor Rx but it's still not changing(8.5khz),
Is this good ? (Sorry for my English)

[Carl-NC]

The TX frequency has nothing to do with the RX coil or the RX capacitor.

[Zinou]

Hi, I have the same problem with big object no detection after 45cm. Can you help me ?

[gurdal]

merhaba usta carl;
Devreyi incelediğinizde uygun bobin değerleri nasıl olmalıdır?
Saygılarımla
Gurdal

[Qiaozhi]

merhaba usta carl;
Devreyi incelediğinizde uygun bobin değerleri nasıl olmalıdır?
Saygılarımla
Gurdal

Please write in English as per the forum rules.

[gurdal]

hello master carl;
When you examine the circuit, what should the appropriate coil values be?
Kind regards
gurdal

[Carl-NC]

I'm not familiar with the Admiral project so I don't know what the intentions were. bonchev2 says TX=1mH & RX=12mH (post 205) which gives a TX frequency of 8500 Hz. In reality, you can use other inductances and adjust the circuit to work at whatever frequency you want. If you haven't done so, read through this entire thread and see what people have done.

[gurdal]

thank you so much

I'm not familiar with the Admiral project so I don't know what the intentions were. bonchev2 says TX=1mH & RX=12mH (post 205) which gives a TX frequency of 8500 Hz. In reality, you can use other inductances and adjust the circuit to work at whatever frequency you want. If you haven't done so, read through this entire thread and see what people have done.

[bonchev2]

You can change frequency by chenging parallel capacitor on TX

[Zinou]

The device works well for coins but does not detect large non-ferrous metals. When I passed with the big object, a strong signal is indicated on tl072 pin 7 but there is no sound indication at all. Has anyone had a similar problem and if so can it be fixed?

Do you fixed this problem ?

[bonchev2]

Yes it was GB potentiometer and also you can change ends of the coils to see that any difference
Good luck

[Zinou]

Yes it was GB potentiometer and also you can change ends of the coils to see that any difference
Good luck

Hi bonchev2, do you mean change polarity of coils ?