Arduino Nano connected relay does not fire when powered by Vin and GND

I am using Arduino Nano V.3 and have sensor connect to one pin and relay and a LED connected to another pin. The LED lights up and relay fires when powered to USB via computer, but the relay does not fire when powered by Vin and GND connection. I use a regulated 5V buck converter to power.
Does anyone have this problem?

Supplying 5V to a Vin pin expecting 7 to 12 volts may be an issue?

Is it a 5V relay? Or does it run on higher voltages?

Hi @sbayub
The supply via pin VIn of arduino nando goes through regulator LM1117-IMPX-5.0.
This regulator needs voltages above 7V and maximum 15V.

RV mineirin

It is a 5V relay.
I check the relay voltage. When powered with USB I get 4.7V to relay. When powered by 120V via 5V regulated buck converter I get 3.7 V. Perhaps this may be the problem. How can I get to a higher voltage?

I'm not sure. Where is the USB power coming from?

Supply 5V power to the 5 Volt pin.

USB is powered by a computer.

I disconnect the USB power then connect it to the buck converter to power to Nano Vin and GND. My project requires connecting the home wall power supply. The buck converter does that to provide regulated 5V to Nano Vin

Okay. Boost that buck converter until it says 5.0V on the VIN pins.

How do I boost the buck converter?

What does it look like? Usually there is a trimpot on top. Just adjust it until you get the correct voltage.

The buck converter does not have a trimpot to change.

Then find some other 5v supply.

Send a picture of the converter if you can. If it has a trimpot I'll show you where it is.

Converter picture


Yeah can't help you there. Those are some OLD parts on that board.

Hi, @sbayub

As has been said in post #7, connect the 5V output of the buck converter to the 5V pin of the Nano.

Are you using a relay module?
Please post a picture of your project.

What old parts?
2 x capacitors, SMD resistor and a transformer???

Tom... :smiley: :+1: :coffee: :australia:

I've only ever seen parts like that in ATX PSUs, which are famous for being like a time capsule to outdated electronics.

Hi, @sbayub
I would not use one of those death trap power supply modules.

It has no proper, infact it has inadequate isolation between mains and 5V output.
Let alone the "fine" example of shoddy soldering.
A danger to the user and the circuit.

Please use a wall plug pack, and throw that "accident looking to happen" in the bin.

Tom... :smiley: :+1: :coffee: :australia:

1 Like

Can you provide a converter suggestion?


Tom... :smiley: :+1: :coffee: :australia: