Arduino Nano PI Main Discussion

[bernte_one]

Yes,I think it's work good on headphones,but I want use speaker.
As bernte_one said,maybe I need to up the PWM voltage to 12V.

Thank your reply ,and bernte_one's

you can also take a simple 2-3w amplifier module
or as main speaker a piezo

if you change the audio frequency in the code you could get louder audio if you use a frequency close the the resonant frequency of the piezo

[lc516]

you can also take a simple 2-3w amplifier module
or as main speaker a piezo

if you change the audio frequency in the code you could get louder audio if you use a frequency close the the resonant frequency of the piezo

Changing the PWM frequency is troublesome in arduino IDE.
so,I just changed the PWM duty cycle to about 5% ("analogWrite(audioPin, 20);"),it look a little better now.

Thanks for your information.

and, I found that if process the audio through the mcu, may get better results.
The current audio processing seems to lose some sensitivity, or it's hard for me to made it well on PCB.

[6666]

If anybody in Australia is interested I have two pcb's for sale, $7 posted, payment by paypal.

[lc516]

...

[Vadim18]

lc516 and bernte, and all who had silent sound with traditional speakers on Surf.
I alredy post modification for audio stage.
https://www.geotech1.com/forums/show...dance-speakers
It will drive 6 Ohm speaker like crazy.
Only 3 transistors.

[lc516]

lc516 and bernte, and all who had silent sound with traditional speakers on Surf.
I alredy post modification for audio stage.
https://www.geotech1.com/forums/show...dance-speakers
It will drive 6 Ohm speaker like crazy.
Only 3 transistors.

Thanks! This solved my recent troubles.

[lc516]

It's exactly the same audio stage as the Surf-PI.
The audio tone increases in volume as the target gets closer to the coil.

Hi,Qiaozhi

I tried to lower R20 to 30ohm,will that get noice on the circuit?

[Qiaozhi]

Hi,Qiaozhi

I tried to lower R20 to 30ohm,will that get noice on the circuit?

It depends on the battery pack used. If you make R20 too low a value, it could potentially cause a voltage drop at the input.
Anyway, you could always try it and find out the answer yourself. It won't break anything.

[lc516]

It depends on the battery pack used. If you make R20 too low a value, it could potentially cause a voltage drop at the input.
Anyway, you could always try it and find out the answer yourself. It won't break anything.

I have replaced R20 to 47 ohm,it looks work OK,This is to increase the volume of speacker.

Thank you for the information.

[lc516]

When I set mainSample to be less than 30us(sampleing starts when the slop of preamp is high), I got this waveform on TP11



This makes the audio output abnormal.
Is that because the capacitance on OPA?

[Qiaozhi]

When I set mainSample to be less than 30us(sampleing starts when the slop of preamp is high), I got this waveform on TP11

[ATTACH]55039[/ATTACH]

This makes the audio output abnormal.
Is that because the capacitance on OPA?

Fig. 4-14 shows the correct position for the main sample pulse relative to the preamp output. If you set the sample delay to start before this point, then the preamp output will either be in saturation or close to it. This causes the audio to sound "abnormal". In fact, this is one method of finding the correct sample position. Start with the sample delay pot set to minimum, and then increase the delay until the audio sounds stable. The minimum sample point is dependent on coil you have connected.

[lc516]

Fig. 4-14 shows the correct position for the main sample pulse relative to the preamp output. If you set the sample delay to start before this point, then the preamp output will either be in saturation or close to it. This causes the audio to sound "abnormal". In fact, this is one method of finding the correct sample position. Start with the sample delay pot set to minimum, and then increase the delay until the audio sounds stable. The minimum sample point is dependent on coil you have connected.

Thanks,
It seems that these problems are due to the fact that my book has not been received.

[Qiaozhi]

Thanks,
It seems that these problems are due to the fact that my book has not been received.

There is an order status button on the Book Depository website, where you can enter your order number and email address.
It looks like you are classed as "Rest of the World", which should take 20-30 business days.
https://www.bookdepository.com

[lc516]

There is an order status button on the Book Depository website, where you can enter your order number and email address.
It looks like you are classed as "Rest of the World", which should take 20-30 business days.
https://www.bookdepository.com

YES,I got it through google that it take about 30 days to receive the book.
I'm not impatient now,and I blieve I can learn more through the book by then.
Thanks!

[dingbatca]

I am happy to report I got my Nano PI running!

Now I am off trying to build a higher performance coil. I have the fast coil article that I have read through multiple time. I started off with a basic round coil, per the book. Then built two elliptical coils, and lastly I tried my hand at making a basic basket coil. Got the basket correct on the secound try. But none of these seem to respond all that much faster. All my coils are right around 18~20uS response time. I have always aimed for the same specs 300~400uH, and I have hit that range every time. Using a spool of 26awg magnet/speaker wire. I know Teflon insulation should help, but I am currently working with what I have. Happy to invest in the better wire, once I have the basic coil building technique hammered out.

Any advice to improve response time?

Pics attached.