Circuit works correctly when powered through usb but not when external power

So I have a circuit that should control WS leds. It also has a bluetooth adapter.
When i power the circuit with usb , it works correctly , but when I power it through external power (5v regulated, which is connected to 5v pin on arduino), the Rx pin is always slightly lit.
Strangely enough the circuit still works, and receives , but i don't like it being buggy .
I don't know if i should post the circuit because it's so simple , the HC module is connected to rx and tx , and power. and that's pretty much it.
I think it's my soldering , but then why doesn't this happen when i power it through usb.
If more infromation is needed to steer my in the right direction i will post more information

DAoliHVAR:
...the Rx pin is always slightly lit.

what do you mean by this ?

is there an LED on the RX pin ?

if you mean the LED on the board indicating the RX activity, i would think that's normal.

BabyGeezer:
what do you mean by this ?

is there an LED on the RX pin ?

if you mean the LED on the board indicating the RX activity, i would think that's normal.

yes the LED on the board.
When the bluetooth module isn't connected to any device yet (in it's default state), I don't think the arduino should be receiving anything, So why would the RX led be on? I thought that it might be receiving garbage because of a short to some other pin, but i can't find that problem.

Hi,

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Is the 5V pure DC?
What are you using for the external 5V supply?

Tom... :slight_smile:

With the bluetooth module disconnected, are you letting that input pin on the Arduino float?

Here is a picture of the circuit , as I said it’s really simple.
Yes with the bluetooth module disconnected that pin is floating.
I tried using a 10Kohm resistor to ground it but that didn’t work.
The TX pin of the HC 06 is constantly 3.3 V , But when i try to send data it works correctly.
Is this normal behaviour for the HC 06 ?

9a9535d2d11c2afb768f5fa581c5c3263ceeab6a.png

Have you measured the 5V pin when you have your 5V supply connected, along with the BlueTooth module? Is it truly running at 5V?

Also, 3.3V is just below the acceptable input for a 5V Arduino. Maybe, because this degrages noise immunity, there is some noise causing that pin to toggle wildly, thus the dim glow on the Rx LED? I know I’m reaching–but seems plausible to me.

Hi,
Thanks for the circuit, where are the WSLEDs and what is the external power supply?

Can you post pictures of your project so we can see your component layout?

Thanks.. Tom... :slight_smile:

Never let an input float. It may be picking up noise. So the Arduino keeps thinking it is receiving something.

DAoliHVAR:
When i power the circuit with usb , it works correctly , but when I power it through external power (5v regulated, which is connected to 5v pin on arduino), the Rx pin is always slightly lit.

If that's the case, then it's probably a good idea to take a look at the specifications or performance of your external 5V regulated power supply. Could also try putting a bypass capacitor across the '5V' pin of the arduino and the GND pin of the arduino.