Arduino Nano PI Main Discussion

[Nightryder]

Does anyone have an issue with the audio? it's really low when I connect an 8 ohms speaker. I even connected 4 (8 ohms speakers) in series in order to raise the impedance but it's still very low. I should mention that when I connect headphones, the audio is not very loud but somewhat is acceptable since the headphones have their own volume pot. The components used are high quality and resistors are (1%) type.

Unfortunately, I can not get a hard copy (paper) of the book , which is the only existing copy, to be delivered to where I live currently due to local laws. So, any help would be much appreciated.

[Emersonpaz]

replace R20 with 47r and use piezoelectric

[Nightryder]

Hello Emersonpaz !

I will definitely give it a try

thank you so much

[Nightryder]

I just did so and it's much better. I remember I tried to attach another (150 ohms) to the soldered one (2 parallel resistors) but I did not notice any change so I figured that was a no go for my issue. But after I followed your trick I knew I should not have given up on R20.

Thank you Sir!!

[Lukelearning]

Hi

I've finally got around to starting this project and I've already messed up!

Starting step 1 all my IC sockets are to small for the PCB. I'm new to electronics and set up my own BOM list but appear to have ordered wrong components e.g the very first one U2 (ICL7660) 8-pin I've ordered https://www.mouser.co.uk/ProductDeta...JZPJ0POQ%3D%3D and its tiny compared to the PCB. As I say, new to all this but not sure the method of choosing the correct component when there are so many there.

Is there an "official" BOM list I can use and try and work out which replacement components I need to order?

Thanks

UPDATE: as the components are so cheap I'll just use the one from here and see how I go https://www.geotech1.com/forums/foru...cussion/page17

[Nightryder]

Hi

I've finally got around to starting this project and I've already messed up!

Starting step 1 all my IC sockets are to small for the PCB. I'm new to electronics and set up my own BOM list but appear to have ordered wrong components e.g the very first one U2 (ICL7660) 8-pin I've ordered https://www.mouser.co.uk/ProductDeta...JZPJ0POQ%3D%3D and its tiny compared to the PCB. As I say, new to all this but not sure the method of choosing the correct component when there are so many there.

Is there an "official" BOM list I can use and try and work out which replacement components I need to order?

Thanks

Your problem is with ICs packaging. You ordered SOP-8 but what you need is DIP-8 and DIP-14. Not sure about Mouser's return/ replace policy, you can check that on your own. There is another solution, which I do not recommend in most cases due to spacing of the PCB, and that is to buy an SOP to DIP converter.

This is a basic knowledge, so do not get frustrated if you don't get responses. This is simply because Google can answer that for ya.

[Lukelearning]

Thanks for your reply. Yeah it seemed very basic, wouldn't be worth the time to get refunds. First of many painful lessons I think but still looking forward to the build!

[Qiaozhi]

Is there an "official" BOM list I can use and try and work out which replacement components I need to order?

The Component Parts List is in Appendix A of the book.

[ugocapeto]

Hi all:

About the coil construction described in the book, I am particularly puzzled by the shielding.

Is it ok to use plain kitchen aluminum foil instead of copper mesh tape?

Can the copper mesh tape (or whatever else) be put on directly on the wire or should there be some kind of air gap between the two?

In a video I saw on youtube about the nano PI detector build, a plastic sheathing is used between the copper wire and the shield. Is that necessary?

Thanks in advance.

[Qiaozhi]

The ANPI is designed for use on the beach so the main sample pulse probably doesn't need to start before approximately 10us, otherwise you'll begin to get false signals if you search in the surf.
In this case you don't need to be ultra cautious about the shielding. A lot of discussions (and videos) about coil building are concerned with getting the shortest sample delay possible. However, this is only really necessary if you're searching for gold nuggets. Also, you would need a detector that includes ground balancing, which is not the case with the ANPI.

I have successfully built PI coils that are shielded with aluminium foil (not thick kitchen foil) that was 20um thick. In that case I used plastic wire wrap to space out the shield.
Eric Foster always used copper mesh tape in his coils, and I have followed his advice as it gives good results.

[ugocapeto]

Hi all, I am not completely sure what to do regarding damping resistor.

Using the tool, it looks like I need 446 ohms to get critical damping.

If I use a 330 ohms, i am at -V for 12.0 us and the time it takes to go to 0v is about 8.8 us. Not sure if that info is relevant.

If I use a 470 ohms, I am at -V for 8 us and the time it takes to go to 0V is about 11.20 us. Note that it's underdamped so it goes above 0V for a tiny bit before coming down.

Now, the question is:

Do I need to use 446 ohms exactly or very close to it or is it ok to use either 330 or 470?

I am thinking 470 ohms should be just fine but not sure tbh.

I have uploaded what the scope shows at TP6 for both resistor values. Hope that helps.

https://imgur.com/a/AZWxpMJ

[Altra]

Use the 470 ohm. It is better to be a little under damped than over. The scope shot for the 470 looks fine

[Qiaozhi]

As Altra says, I would go with 470R.

[GeoMax]

Why do you not place two resistors in series to get your desired resistor value? For example take maybe 390R + 56R in series to get 446R.

[ugocapeto]

Thanks a lot for your replies, well appreciated.

Yes, at some point, i will put a damping resistor that makes it closer to the critical value. Was just wondering if a little bit of underdamping was ok.

I am trying to get to the finish line and was wondering if you could tell me if those scope traces look ok, in particular, the signal at TP10. I am at step 13 in the book. I don't understand why the sample pulse is so large, time wise.

See here the traces i am getting at TP6. TP5, and TP10: https://imgur.com/a/1jamqw8

The book says I should get 700mV DC at TP10, but i am nowhere near that with this sample delay as it's actually negative.

Not too sure what I am doing wrong here. Again, thanks for your patience.