hbridge help

[donkey]

hey guys. am hoping someone is willing to help me out on something that I think is very easy but for some reason I just can't figure out.
I am trying to make an 18volt out hbridge that hooks up to arduino. I see a few that are for lower end motors (9v being the highest)
what I want to do is be able to is hook up say 9volt and use the Hbridge on a 9volt motor but if I hook up 18volt to drive an 18volt motor not change anything except the motor and voltage.
the pin out would be 5volts at about 40ma if that helps with the circuit and am hoping to get up to 5amp at 18volt

 

[(*steve*)]

You almost certainly need one or more transistors to give you a level shifter.

If you take a look at the circuit at the bottom of this page you will see that the upper two transistors are fed from another transistor which acts as a level shifter (actually it is an open collector output, but in this case it's all you need)