For a homemade H Bridge of that calibre, you could do it with 2x SPDT relays. If you need PWM control, you need 1 MOSFET between the relays and power source.
because the coil in the relay is going to suck a lot of current isn't it?
You do appear to need 2 different PWM signals to the board, and what are the parameters of the current and voltage signal out? Unfortunately, they rarely seem to have much documentation.
Quotebecause the coil in the relay is going to suck a lot of current isn't it?Depends on the relay but 20 to 100 mA is not a lot.
If you are considering using relays, you might instead get two switches like below (one for each motor).http://www.radioshack.com/product/index.jsp?productId=2062530