# Circuit bricks Nano (power supply)

Status
Not open for further replies.

#### Nard

##### New Member
Hi, I am making a module for a DIY modular synthesizer. The module applies an ADSR-envelope to an audio signal using a 10K MPC41010 digital potentiometer.

I suspect, I made an error in the circuit, since I now have 2 Nano's which will not power on from USB (pwr led flashes a few times and then stays off). Attached you find the circuit and the pinout of the MCP41010. The second Nano I tried without audio-in/audio-out/gate cables attached, so I know it is not the audio signal causing this.

So I drawn out the circuit I used for the first and second Nano and am ready to build this for the third Nano taking extra care to connect al thing correctly. Just to be safe, am I doing something wrong in the circuit (sinking too much power perhaps)?

Any help is much appreciated!

#### Wp100

##### Well-Known Member
Hi,

Are you applying any voltage to the Power In connector and if so, what voltage ?

If you are powering the Nano from the USB connector, do you have any voltage connected to Vin as well ?

The Pots , IC and Switch should be connected to the Nanos +5v output pin, not Vin, which needs to be between +7v to +12v.

Your Gate switch wiring means that pin is left Floating, it should be properly connected 'PulledUp or Down'
https://www.arduino.cc/en/tutorial/button

#### Nard

##### New Member
Hi,

I have changed it, so it is now all connected to 5V from Nano. (see attached circuit below). Up until now I just powered it from USB. Later when all is tested, I will connect Power In to a regulated 5V supply.

The Gate Switch was pulled up in code. Sorry for not pointing this out. The code I used:
Code:
int GatePin=3;
pinMode (GatePin,INPUT_PULLUP);

Could any of this have damaged the voltage regulator on the Nano itself? I checked my solder work with a multimeter for shorts, but could not find any...

Last edited:

#### Pommie

##### Well-Known Member
Try unplugging the Nano from the board and power it via USB. Program the blinky code to see if it works. If it doesn't then you may have to reflash the Nano - instructions on web for this.

Mike.

#### Wp100

##### Well-Known Member
Hi,

Could any of this have damaged the voltage regulator on the Nano itself? I checked my solder work with a multimeter for shorts, but could not find any...

View attachment 117666

If you ran the circuit from the Power In socket with more than 6v then you could have damaged the Nano and the MCP41010 as both are rated at 5v5 maximum.

Over volting may appear not to have harmed them, but it can later lead to early failures.

Do try as Pommie suggests and run the blink test, but also unplug the MCP41010 in case that is pulling things down.

#### Nard

##### New Member
Thx,

I power it from USB only, so luckily no overvoltage to the nano or chip.

I have disconnected the Nano from the board and connected it via USB to pc. The pc does not see it and after a few flashes of the Nano pwr led the led stays off.

I did notice something else: If I power it from a separate 5V regulated power supply, the pc sees it over USB and I can flash with the blink sketch, which works fine.

However the main question remains: Did my circuit design cause this?

Any ideas?

Last edited:

#### Pommie

##### Well-Known Member
It looks like you have somehow blown D1 - see center bottom of the schematic. Or maybe the fuse F1.

However, it appears to be completely usable once powered separately or with the diode/fuse replaced.

Mike

Status
Not open for further replies.