[SOLVED] Nano using 9v on Vin works weird

Using Arduino General Electronics
#1

I’m doing a little synth with a Nano and some other stuff (filter & fuzz)
When I connect it by USB it works fine and produces sound, but when I connect 9v (also tried 12v) on the Vin pin, it works but the output is faint and there is a lot of noise.
I must say that I’m probing the output after the Nano, before getting to the filter and fuzz.

The strange thing is that when I touch the USB input of the Nano with the outside of the mini USB plug that is connected to the PC it works fine, without reseting or anything, just by those two touching the noise dissapears, removing it noise comes back.

I’m attaching the schematic!

Heeeeelppp pleeeasee! Thanks!

AO_schematic.jpg
AO_schematic.jpg934×778 53 KB

#2

The chip only handles 5v!

#3

How about your common grounds. Is the grounds connected when using battery, or just when using USB ?

#4

The 5V coming through USB is filtered. Though the 9V should not be noisy enough to create what you are describing.

You can try adding 0.1uF and/or 4.7uF caps between Pos and Neg close to the battery.

#5

How much current is your circuit drawing?

When powered through Vin, you are using the on-board regulator. When powered through USB, you are not.

So you may either be exceeding the current rating for the on-board regulator, or enough current is flowing that it is causing it to go into thermal shutdown.

#6

but when I connect 9v (also tried 12v) on the Vin pin, it works but the output is faint and there is a lot of noise.

If the regulator went to thermal shutdown, it would be off for a while. But if there was not a common ground, it cold produce such symptoms. Where's the OP. Maby they have a hopping weekend, and left us till Monday. LOL

#7

The strange thing is that when I touch the USB input of the Nano with the outside of the mini USB plug that is connected to the PC it works fine

That means you haven't got a common ground between your arduino and your audio circuits.

#8

jackwp:

but when I connect 9v (also tried 12v) on the Vin pin, it works but the output is faint and there is a lot of noise.

If the regulator went to thermal shutdown, it would be off for a while.

Thermal shutdown isn’t an “on/off” action. The output voltage and current will begin to drop.

#9

Thanks for that info James. I must have misunderstood.

#10

How about your common grounds. Is the grounds connected when using battery, or just when using USB ?

I don't use a battery, I'm using a 200mA 9V power supply, I just connected GND to ground but I think I also tried connecting it to GND1 also.

The 5V coming through USB is filtered. Though the 9V should not be noisy enough to create what you are describing.

You can try adding 0.1uF and/or 4.7uF caps between Pos and Neg close to the battery.

This also applies to a power supply?

If the regulator went to thermal shutdown, it would be off for a while. But if there was not a common ground, it cold produce such symptoms. Where's the OP. Maby they have a hopping weekend, and left us till Monday. LOL

why a thermal shutdown? It's not that the Nano goes off, it just produces a noise audio output. [u]Also tried a blink program and it works fine with the power supply only.[/u] Could it be that is a noise power supply? Is there a way to reduce that? Maybe with a capacitor as said above? I'm sorry, I haven't been in the PC all this time to answer!!! XD

Grumpy_Mike:

The strange thing is that when I touch the USB input of the Nano with the outside of the mini USB plug that is connected to the PC it works fine

That means you haven't got a common ground between your arduino and your audio circuits.

No no, everything has common ground! Im using only the one on the power supply, also I'm probing on the audio output of the schematic (on the right)

#11

Does that probe use one signal wire plus one GND wire (and if so, did you connect that GND wire) ?

#12

Pancra85:

How about your common grounds. Is the grounds connected when using battery, or just when using USB ?

I don't use a battery, I'm using a 200mA 9V power supply, I just connected GND to ground but I think I also tried connecting it to GND1 also.

The 5V coming through USB is filtered. Though the 9V should not be noisy enough to create what you are describing.

You can try adding 0.1uF and/or 4.7uF caps between Pos and Neg close to the battery.

This also applies to a power supply?

If it's Chinese made, anything's possible. If you have some caps lying around, throw some in and see if it makes a difference.

Describe the "noise" you are hearing. High or low frequencies?

#13

Ok, this is becoming a mystery. Come on guys. What could this be?

With a volt meter, check from arduino ground, to the other grounds. Should be close to zero. A loose wire on the breadboard could cause problems. Check while audio is running weird.

What is the difference between GND and GND1 ?

#14

Pancra85: why a thermal shutdown? It's not that the Nano goes off, it just produces a noise audio output.

The output being faint could be due to the regulator shutting down.

The noise you are hearing is most definitely coming from the supply. Sounds like it isn't well regulated, or at least, not as well as your USB's supply.

I misunderstood your initial description. I thought "noise" meant output, not actual unwanted noise.

#15

No no, everything has common ground! Im using only the one on the power supply, also I'm probing on the audio output of the schematic (on the right)

Check that the wiring is actually making contact. What you describe is classic no common ground. Sorry but there you are. Maybe a photo of your setup?

#16

Grumpy_Mike:

No no, everything has common ground! Im using only the one on the power supply, also I'm probing on the audio output of the schematic (on the right)

Check that the wiring is actually making contact. What you describe is classic no common ground. Sorry but there you are. Maybe a photo of your setup?

What an idiot... I forgot to ground the audio output :blush: For some reason when using USB power the audio doesn't needs a ground (when connected to the same PC I suppose)

THANKS to you all!!!!!

#17

I am glad you have it solved. If you go back to your first post, and modify it , change the title adding (SOLVED), others may be able to learn from this thread. Thanks.

#18

I finished it! Thanks again, here it is if you want to take a look at it... http://forum.arduino.cc/index.php?topic=184158.0

I think it has quite an original sound

#19