Arduino Nano PI Main Discussion

[MartyJ1963]

Hiya Trev,,,,Hope you and Bridgitte are well! I only saw your email the other day because I've been having trouble lately with my PC and something went wrong with Microsoft Outlook for some reason! When It finally started working and I got logged in I found 1,000's of emails!! It was really overwhelmng and took me hours to read through everything etc,,,! Lol. Thanks for remnding me what 'SS' stands for,,I remember now,,Lol. Say Hi t Bridgitte and I'll be writing to you soon. Take care for now and stay safe, Regards, Marty.

[Goaty]

All good Marty. No rush for reply as it looks like you have enough on your hands at the moment!
Cheers
Trev

[Qiaozhi]

As I am genuinely curious; what would it take to tune the Nano Pi to search for gold? I have a little 0.35 gram gold nugget that my Simplex+ can see at 4 inches. But my Nano Pi cant seem to see it at all.

Probably a rework of the RX preamp design and adjusting sample timing and sample delay.
A small piece of natural gold has a very short TC. Therefore one must sample early to detect the very short decay.

You would also need to implement ground balance.
Take a look at this -> UXO Target Detection and Discrimination with Electromagnetic Differential Illumination
There's an Arduino sketch which uses the well-known subtractive method, and it's possible to get the sample delay down to 8us. You could even sample earlier than that by directly accessing the ports and not using digitalWrite(). However this presumes you have a fast coil, have modified the Tx circuit (as shown in the "Investigation of UXO paper.pdf"), and possibly modified the preamp.

[dingbatca]

Qiaozhi (George). UXO is interesting. My end goal is "direct sampling with a much more powerful processor" using a Black Pill. That in combination with some code ported over from the STM32-O-Scope project to allow visualization of any test point on the circuit board in the field, with out the need of a full scope. Basically a PI metal detector that is mostly firmware with minimal electronics. Electronics are scary! My skills are in firmware. :-)

Perhaps I should be asking what the best TX and pre-amp circuit's are? Wow, that's a loaded question! This rabbit trail might be worthy of a different thread.

[Qiaozhi]

Perhaps I should be asking what the best TX and pre-amp circuit's are? Wow, that's a loaded question! This rabbit trail might be worthy of a different thread.

In terms of existing [and known working] projects, I would suggest using the Voodoo transmit circuit and PI preamp, as this can be driven from a micro.

[lc516]

In terms of existing [and known working] projects, I would suggest using the Voodoo transmit circuit and PI preamp, as this can be driven from a micro.

Hi,Qiaozhi
I'm also concerned the issue that what the best preamp.
What is "Voodoo transmit circuit and PI preamp"? Can you show schematic of it?

[Qiaozhi]

Hi,Qiaozhi
I'm also concerned the issue that what the best preamp.
What is "Voodoo transmit circuit and PI preamp"? Can you show schematic of it?

See attached files.

[dbanner]

Arduino nano RP2040 same form factor as the nano but a whole lot more. Maybe this can open more possibilities for development.

[6666]

Arduino nano RP2040 same form factor as the nano but a whole lot more. Maybe this can open more possibilities for development.

Looks good, this write up points out a few issues
https://www.tomshardware.com/reviews...rp2040-connect

[dbanner]

You could utter the words "beach mode" through a Bluetooth headset and presto!

Our friends in eastern Europe might say " bittch mod" , which might cause a different effect, now all targets become rejected!

[MartinB]

Looks good, this write up points out a few issues
https://www.tomshardware.com/reviews...rp2040-connect

Too many issues to be resolved, and expensive!

[Agme]

I am new to DIY Detectors and have a quick question about the BOM components.
What should the capacitors voltage and tolerance be?
What wattage rating should the Dampening Resistor be?

Thanks

[Qiaozhi]

I am new to DIY Detectors and have a quick question about the BOM components.
What should the capacitors voltage and tolerance be?
What wattage rating should the Dampening Resistor be?

Thanks

Have a look at post #243 where dingbatca posted a BOM with Tayda part numbers. This should provide some useful information.
https://www.geotech1.com/forums/show...438#post287438
I always use 1% tolerance resistors. Capacitors generally have a much wider tolerance, such as +/- 10%. Nothing is really critical in this design, and some people even build their projects from parts rescued from scrap boards. I would use a 2W component for the damping resistor.

[Agme]

Thank you. I did look at that BOM and it was very helpful, but they didn't have Rd part # (for obvious reasons). They specified some 100V caps and some 16V, I was just a little confused about what they needed to be. Sorry if these are basic electrical questions I am learning (slowly).

Thanks

[Qiaozhi]

Thank you. I did look at that BOM and it was very helpful, but they didn't have Rd part # (for obvious reasons). They specified some 100V caps and some 16V, I was just a little confused about what they needed to be. Sorry if these are basic electrical questions I am learning (slowly).

Thanks

You just need to specify the capacitor voltages to be higher than what they will be subjected to in the circuit. For the Arduino Nano PI none of the capacitors will be exposed to more than 16V. If the component has a rating higher than 16V, then it will obviously also be OK. The next important thing to check is the pin spacings, and these are listed in Appendix A.