I was wondering if it is ok to use the 5 volt of the arduino
my circuit is using 4 L293D circuits,
each one of them consume 30 mA
I have an external tension of 10 volt that I can step down to 5 volt using a buck converter
right now I am simply using the 5 volt of the arduino,
Is that recomanded ?
You'll want to read the spec for the 5V on the aRduino Uno.
The 5V pin can supply 500-800mA, depending on the voltage at the barrel jack.
I would think 120mA from 10V supply would be okay.