HELP Choosing a design for first digital PI build

[gdane]

New to these forums and to DIY detector builds. I'd like to build a digital PI detector to experiment with DSP, but there are *so* many designs out there I'm not sure where to start.

I know of the Arduino Nano Pi project from these forums that seems to be well accepted. I've also seen more recent ones on Hackaday and Element14, but coming from a software background I really don't know how to evaluate the hardware side of these projects. I want to be sure I have a solid (and ideally flexible) analog front-end before I embark on DSP pursuits.

Hoping that folks here can weigh in and help guide me in selecting the best design to start with. Are there any projects that really stand-out above others?

Here are links to some of the other projects I've found:

• https://hackaday.io/project/190934-d...ce=chatgpt.com
• https://neco-desarrollo.es/pirat-wir...metal-detector
• https://community.element14.com/chal...w-to-build-one

[algan]

Hi, Gdane, I am also interested in similar projects and would like to learn more about how signal processing is done. Can you explain what happens in the circuit chip, and here the samples cannot be measured with an oscilloscope, or are they sampled in the chip according to the written code?

[Qiaozhi]

New to these forums and to DIY detector builds. I'd like to build a digital PI detector to experiment with DSP, but there are *so* many designs out there I'm not sure where to start.

I know of the Arduino Nano Pi project from these forums that seems to be well accepted. I've also seen more recent ones on Hackaday and Element14, but coming from a software background I really don't know how to evaluate the hardware side of these projects. I want to be sure I have a solid (and ideally flexible) analog front-end before I embark on DSP pursuits.

Hoping that folks here can weigh in and help guide me in selecting the best design to start with. Are there any projects that really stand-out above others?

Here are links to some of the other projects I've found:

• https://hackaday.io/project/190934-d...ce=chatgpt.com
• https://neco-desarrollo.es/pirat-wir...metal-detector
• https://community.element14.com/chal...w-to-build-one

The Arduino Nano PI is the most sensitive of all these projects.
The Hackaday project claims 30cm on a coin. ANPI gets a definite signal at 36cm, and a faint signal at 43 cm.
The Spirit PI uses very simplistic hardware, and you can readily see from the video that the sensitivity is poor.
The last link (Element14) is broken.

[algan]

Yes, I agree that I made an Arduino Nano PI and the threshold and sensitivity are better than those of the Surf Master. The Hackaday project shows that it is shallow, where exactly does it happen and what is the sampling, I am not aware of this project. I have a few boards left, Arduino Nano PI if anyone wants it, you can buy it from the link.
https://www.ebay.com/itm/116935111684

[gdane]

Sorry, don't know how those links got abbreviated. Here they are again, hopefully in their entirety:

• https://hackaday.io/project/190934-d...metal-detector
• https://neco-desarrollo.es/pirat-wir...metal-detector
• https://community.element14.com/chal...w-to-build-one

For those who can't seem to access the Element14 design, the schematic is attached.

[gdane]

Yes, I agree that I made an Arduino Nano PI and the threshold and sensitivity are better than those of the Surf Master. The Hackaday project shows that it is shallow, where exactly does it happen and what is the sampling, I am not aware of this project. I have a few boards left, Arduino Nano PI if anyone wants it, you can buy it from the link.
https://www.ebay.com/itm/116935111684

Thanks for the offer! Any idea what actual transit times are like for shipping to US?

[gdane]

Hi, Gdane, I am also interested in similar projects and would like to learn more about how signal processing is done. Can you explain what happens in the circuit chip, and here the samples cannot be measured with an oscilloscope, or are they sampled in the chip according to the written code?

Yes indeed samples of the RX are measured by the MCU, which is also responsible for generating the TX pulse. What would stop you from also measuring RX with an oscilloscope?

[gdane]

Thanks all for the input. Sounds like Arduino Nano PI is the way to go. Any other projects that haven't been mentioned here that anybody knows of?

[gdane]

Forgot to also mention the Voodoo Project. Curious where this one stands in relation to the Arduino Nano Pi.

[Qiaozhi]

Forgot to also mention the Voodoo Project. Curious where this one stands in relation to the Arduino Nano Pi.

The Arduino Nano is a standard PI, whereas the Voodoo Project adds ferrous discrimination.
The original Voodoo uses a PIC Microcontroller, but there is also an Arduino add-on board that can replace the PIC.
Voodoo is a lot more complex hardware-wise than the ANPI. Personally, I would start with the ANPI, as it would be possible to add ferrous discrimination later in the project if that's required.
A lot depends on what you want to achieve.

[algan]

Thanks for the offer! Any idea what actual transit times are like for shipping to US?

Today I asked at our post office, they couldn't tell me specifically how many days it takes to get to the United States, it's approximately 2 or 3 weeks for delivery, it's like a letter.

[gdane]

Today I asked at our post office, they couldn't tell me specifically how many days it takes to get to the United States, it's approximately 2 or 3 weeks for delivery, it's like a letter.

I pulled the trigger on your listing. I'll just have to be patient and wait for it to cross the pond ;-).
You wouldn't be able/willing to include all/most parts from the BOM in a separate listing too would you? Since I'm a software guy my collection of electronic parts is pretty slim.

Thanks!

[algan]

I pulled the trigger on your listing. I'll just have to be patient and wait for it to cross the pond ;-).
You wouldn't be able/willing to include all/most parts from the BOM in a separate listing too would you? Since I'm a software guy my collection of electronic parts is pretty slim.

Thanks!

I sent the letter with the board today. I hope you will receive it within two weeks, I have not considered it for a separate listing with elements, but it is a good idea. From this YouTube channel you can follow the step by step implementation of Arduino Nano Pulse induction, there are several parts, when the first part is finished you choose to play the second and so on, this is the first part, here is a link to it.
https://www.youtube.com/watch?v=xh8a2hOa29I

[haylaz0036]

I want one too, but a professional one with the full hex file. Do you have such a digital pulse file on the site or in your archive?

[algan]

I want one too, but a professional one with the full hex file. Do you have such a digital pulse file on the site or in your archive?

here is the archive for the Arduino Nano Pulse Induction Metal Detector project you can download the programming file https://www.geotech1.com/forums/foru...hed-march-2021