microcontroller outputs 3v instead of 5 on HIGH state

Ive made this design withc worked at first, but now I dont know why the micro controller does not drive the reley anymore. when I measure the D0 output it shows 3.6V, when it should be 5v. Ive tried using an arduino pro mini instead, but its the same, no improvement.

What am I doing wrong?

catalin123m:
What am I doing wrong?

Providing an fzz when not everyone uses Fritzing....

would a photo be more of use??
and here is a little video from when it worked - YouTube
you can hear the relay

We would need the schematic, not the board layout.

I didn`t made a schematic. I directly designed the pcb and then followed it to solder the components

But you do realize it's completely impossible for anyone else to know what's what, right?

I just figured it out :D:D:D. It was the relay. I connected another relay and it works. I don`t know what happened with the other one, because when I connect it to 5V directly, it makes the click sound.

catalin123m:
I don`t know why the micro controller does not drive the reley anymore.

How you drive the relay? show us the connection diagram.

Is the relay coil connected directly to the Arduino, or is it a relay board with a driver circuit?

If the relay is connected directly to the Arduino, what's the current rating on the relay coil? (I assume it's rated for 5V?)

The Arduino is rated at 40mA maximum and if the relay coil requires more than that, it won't work reliably. ...Even at 40mA it could be marginal because the 5V will drop somewhat with the maximum load.

And don't forget the freewheeling diode!

...in any case, how do you expect people to help you troubleshoot a circuit nobody knows what is?

What am I doing wrong?

Posting the same question THREE times.