Bipolar PI MD with GB and DD Coil

[pechkata]

Bravo...

[Detectorist#1]

For common progress with common efforts!

[pito]

and what is the advantage compared to not bipolar ?

[Detectorist#1]

Hi pito,
The advantages of bipolar PI:
1. Eliminated 1/f noise of 1-st stage - possible use of more cheap IC
2. Eliminated influence of magnetic field of the Earth - no need of EFE samples - more simple control pulses
3. No need of sophisticated schematic for automatic moving of the positions of the sample pulses for big or too near targets as in the schematic of Delta Pulse (XR71) MD
4. This solution safe lives - no danger of exploding of mines with magnetic triggering
I hope, this list answers to your question.

[usefi5961]

Hi pito,
The advantages of bipolar PI:
1. Eliminated 1/f noise of 1-st stage - possible use of more cheap IC
2. Eliminated influence of magnetic field of the Earth - no need of EFE samples - more simple control pulses
3. No need of sophisticated schematic for automatic moving of the positions of the sample pulses for big or too near targets as in the schematic of Delta Pulse (XR71) MD
4. This solution safe lives - no danger of exploding of mines with magnetic triggering
I hope, this list answers to your question.

Very nice pi detector ,good luck.

[Detectorist#1]

And fifth reason - Carl declared he now design only bipolar type of PI MD - follow the motto - "IN CARL WE TRUST"

[algan]

Hi, Detectorist#1, do you sell boards for customers in Bulgaria to order from you? There was a colleague who wanted to contact you, if he could leave me a viber or phone number. Thank you.

[Detectorist#1]

Hi algan,
The project of the two PCBs is property of GeoMax. Only he sell the set of the two PCBs on eBay.
https://www.ebay.de/itm/128018846245...Bk9SR6SxzeGAaA

[algan]

Hi algan,
The project of the two PCBs is property of GeoMax. Only he sell the set of the two PCBs on eBay.
https://www.ebay.de/itm/128018846245...Bk9SR6SxzeGAaA

Okay. Thanks, my colleague and I should order from there.

[GeoMax]

Okay. Thanks, my colleague and I should order from there.

Hi Algan,

If you place a joint order with your friend, you can save on shipping costs. Each additional PCB set is included at no extra shipping cost.

[Detectorist#1]

Hi,
After many tests in real different grounds last weeks, I understand why the serious manufactures not use in PI MD delays under 10us ( the reason isn't the level of the skills of the engineering staff). All tests in air with lower delays are OK (possibility to catch more smaller nuggets including the sizes of 1grain) but the tests in real grounds shows many problems. This have as result some changes in the schematic of "Dual Tone Pulse Detector Rev.B" The first change is increasing of the min "Target Delay" from 5us to 10us. For this change, the value of C41 have to be increased from 220pF to 470pF. For compensate of the "base sensitivity" level, the value of RT1 have to be changed from 20K to 100K and set from average 10K to average 50K. For avoiding of opposite second tone after the target detecting, the C6 capacitor have to be shorted. Good news is that for these changes no need to make any changes is the PCB project.

[Carl-NC]

I'll have to disagree. The prototype PI designs I'm working on have delays of 4us and they work just fine, even in Australia. What problems are you having?

[Detectorist#1]

It is not easy to answer to your question. I living too far from Australia - in Bulgaria. Also, in popular TV shows for Aussie Gold searchers very often the finds are nails - not gold nuggets. The sound of the MD not predict the type of the find. What are the different real sounds from your PI MD with 4us delay for different targets?

[Detectorist#1]

Hi Carl,
First, It is very good that you so quicly restore the possibility to be involved in this great platform for all MD enthusiasts!
With more deep analysis of the RX signals with microprocessor's treatment, maybe more exact conclusions for the type of the targets have to be possible - but this is out of my knoloweges.

[Carl-NC]

It is not easy to answer to your question. I living too far from Australia - in Bulgaria. Also, in popular TV shows for Aussie Gold searchers very often the finds are nails - not gold nuggets. The sound of the MD not predict the type of the find. What are the different real sounds from your PI MD with 4us delay for different targets?

The responses of 4us sampling are the same as 10us sampling, you can just hit smaller gold. My question was really directed at: "but the tests in real grounds shows many problems." As you decrease the sample delay, the response to ground increases so you must reduce the preamp gain and maybe even the demod gain to avoid overloading the front-end. If overloading was your problem.