External power supply of 18V

Other Hardware Motors, Mechanics, Power and CNC
1

Hey guys,
i was wondering if there is a maximum voltage for an external power supply on my breadboard?
Because normally, that power supply just feed my DC engins and the current doesn't enter my arduino board, or will it?

The situation is like this: for a project i'm using 2 DC-motors that i control with a dual H-bridge. I do exactly the same as the picture shows. The only difference is that i'm using a 6V battery with 4A and the engins i have, have a limit of 0.3A (so it shouldn't damage my H-bridge) . But the engins are more powerfull with a higher voltage (18V), that's why i want to use a 'set up converter' to convert my voltage to 18V. I know arduino has a maximum voltage of 12V, but the external power supply of 18V doesn't enter arduino (that's is what i pretend!!), so will it still be able to damage it? Or should i use a diode to prevent the current going into arduino?

Thank you a lot for answering!

hbridge-dual-motor_bb (1).jpg

2

Should be okay with under ONE amp of current

3

Can i use diodes to be sure current doesn't enter arduino? And where should i place them?

4

Diodes aren't needed(*), just make sure the 18V only goes to the
motor supply pin and grounds are commoned.

(*) well, if you are paranoid you could arrange a diode from the Arduino 5V to the 5V
supply of the motor driver chip, and add 10k resistors in series with each signal wire
between Arduino and driver. This protects the Arduino should the driver chip completely
fry.