Hi people.
I would need your help, have an old toy tank. There are 2 motors. I want to build an you know ultrasonic sensor car that finds its way. Sensor will be on servo. I bought a motorshield but I recognized there is no space for that sensor! So I have to use my own H bridge.
I need to find H bridge mosfet N and P channel combo to control 9V motor that draws around 200-300 mA. Could somebody help me? Thank you. I am newbie.
Building your own H-bridge is instructional but there's so many modules available on the market at such low prices that it's really easy to find one that does what you want in one small package. Once you know enough to know what an H-bridge is, then you just need a little bit more learning to go out and pick a module that does what you want. To be able to select MOSFETs and their associated driver circuitry requires a degree in Electrical Engineering or a huge amount of experience in the field.
Can I use something like this? Is this right? Take a look on it please 
I've never used a HG7881 chip but I'm sure it's better than anything I could design within the next 6 months. 800mA max is kind of small. Any toy tank I can think of is likely to use 2A but if yours is an especially small one, it might be OK.
The image is mirror-reversed. That's not a good sign for an eBay listing. They may have ripped it off from somewhere else and the unit you get won't look like that. You don't lose a lot of money if they ship you junk but you lose time and gain personal stress. If you think their other listings look legitimate, then it's probably OK to buy this one.
Firstly measure the stall current and make sure the bridge can handle that without damage.