Bipolar PI MD with GB and DD Coil

[Detectorist#1]

Hi,
The oscope pictures for the first variant of the schematic of the TX part of the detector points very equal parameters for positive and negative peek voltages on the TX coil - as voltage and time to decay (360V and 5us) . Maybe it is not so difficult to use P-ch and N-ch MOS FETs in half-bridge schematic. Also, I will test next week IPA50R800CE N-ch MOSFET in this design. The parameters (Rds-ON and Cds at Vds 25V) are very close to the same parameters of IXTP10P50P P-ch MOS FET. Maybe IPA50R800CE is more easy to be used as pair to ITXP10P50P in well balanced half-bridge TX PI designs.

[algan]

Upload pictures from the oscilloscope, it would be interesting and visual.

[karakus]

Hello, is there a PCB file for this circuit?

[Detectorist#1]

Yes, me and GeoMax have PCB files for this project but they will be posted after serious tests in real fields.

[AhmatAhmatov1959]

Жди. Скоро информация будет. Wait. Soon we, me and GeoMax will give information.

Hello. What transistors would be the best replacement for 2N3604 and 2N3604 transistors. ALI doesn't have them, thanks for the answer

[Detectorist#1]

BC547A or BC547B as NPN and BC557A or BC557B as PNP from Europe. But any low power NPN and PNP with Beta 100-500 and TO-92 case will work.

[Prince Zhakata]

Do any one know how to design a ground balance circuits an automatic one? Auto ground balance for metal detectors either programmable or using digital circuits...

[Detectorist#1]

Hi Prince Zhakata,
And when the target changes the RX answer, this automatic Ground balance what will do?

[AhmatAhmatov1959]

Hi,
The oscope pictures for the first variant of the schematic of the TX part of the detector points very equal parameters for positive and negative peek voltages on the TX coil - as voltage and time to decay (360V and 5us) . Maybe it is not so difficult to use P-ch and N-ch MOS FETs in half-bridge schematic. Also, I will test next week IPA50R800CE N-ch MOSFET in this design. The parameters (Rds-ON and Cds at Vds 25V) are very close to the same parameters of IXTP10P50P P-ch MOS FET. Maybe IPA50R800CE is more easy to be used as pair to ITXP10P50P in well balanced half-bridge TX PI designs.

Hello. Is it possible to use a pair of transistors 2SJ116 2SK299 Thank you

[GeoMax]

Do any one know how to design a ground balance circuits an automatic one? Auto ground balance for metal detectors either programmable or using digital circuits...

Hello Prince Zhakata,

Check out the Sniffer XR71 circuit. This detector features automatic ground noise suppression.

Sniffer_XR-71_sch.pdf

[Detectorist#1]

Hi AhmatAhmatov,
Yes. The using of 2SJ116 and 2SK299 is possible. RdsON of 2SK299 is 1.1R typical and RdsON of 2SJ116 is 1.75R typical. In this case, serially connected resistor with 2J116 have to be 0.15R and serially connected resistor
with 2SK299 have to be 0.82R. These transistors are in very old TO-3 case. This case is very inconvenient in practical use. The cases of these transistors have to be electrically isolated - on the Drains have appr. 350V pulses.

[Prince Zhakata]

Thanks guys for your answers and help some of the gold rich areas here in my country Zimbabwe the ground is iron infested soil thats heavy mineralized soil here where gold is found the most.
Last time i designed a metal detector without ground balance it was crazy to detect anything. What i end up doing to detect something i put the search head on the ground then i adjust the threshold to near some little popping sounds then i rise the serch head a bit then i search but if i pass some changes on the ground like bumps there will be a swiquiking sound like there is a target or hot rocks i dig most of them like hell that was horrible without iron rejection circuit on my metal detector.