I have assembled a MOSFET h bridge from this design: http://www.armory.com/~rstevew/Public/Motors/H-Bridges/Blanchard/figure-1.htm
I used the P channel IRF954, and the N channel MOSFETs IRF1405 Data sheets here http://www.armory.com/~rstevew/Public/Motors/H-Bridges/Blanchard/figure-1.htm and here http://www.jaycar.com.au/products_uploaded/zt-2468.pdf
I used 2n3904 transistors to control the mosfets, as specified in the circuit diagram, and I am using +5v from the arduino to turn them on.
On testing the circuit, i found that the motors (6v cordless drill motors) ran slowly or not at all, in some cases heating up and burning out one of the N-channel MOSFETs in the circuit.
The grounds of the arduino and the 6v (yes, I know the diagram says 12v) supply for the motors are ganged together as it doesn't seem to work at all otherwise.
I have found that the device works when the supply for the motors is 12v, AND when the 2n3904 transistors are turned on by the same supply (by touching the signal wires to the battery terminals)
Can anyone please tell me why it doesn't work, why it does work with 12v signal and/or how I can make it work with the 5v arduino signal voltage and either a 12v or 6v supply?