Okay, so if I’m using the GHM-13, does that mean I need MOSFETs that can take 3.8A?
Also, what battery would do the job here?
I want a good, worry free battery type that doesn’t have a memory effect as the robot will be recharged frequently etc…
theChipmunk
those are the pair Im actually getting myself too. Im affraid I bought a pair of 200 rpm motors with 39. stall torque last year and their not doing the job. So I also recomend those motors.
ok, I think your gonna need a motor controller of some sort, like the scorpion dual motor controller.
Im a rover guy.
this may be a little off topic guys, but has anyone ever thought of using this motor controller?
lynxmotion.com/Product.aspx?productID=493&CategoryID=10
i found it hiding at the very bottom of the motor controller page
WOW, I havent seen that in a while 
I dont think its a good bet to buy it for 40 $$ when you can buy the scorpion for 30 $$ more and get more out of it. 
but thats my 2 cents
but it has such a higher rate of amperage peak, and it can run 2 motors, and wat more can the scorpian do?
Remember, 3.8A is a locked shaft (full stall). This is for each motor… you stall all 4 and that’s 3.8A x 4. I did a mA “no load” test on 4 of these motors at once (that is spinning freely in the air). The 4 motors were drawing around .6 to about .7 amps (this is all 4 combined). So all motors are drawing less than an amp with little or no load. I would say to be safe, a 10 amp mosfet would be enough (just in case you lock the shaft on more than one motor). A 5 amp one would be ok if you were not carrying the load you plan to. As far as the battery is concerned, you need tp buy or make a 12V NiMH (I recommend NiMH because they are safe, powerful and have no “memory effect”). I couldn’t find a decent 12V pack on the internet so (but they do exist) I made my own from ten 3500 mAh 1.2V sub “c” cells (they are matched cells for safe charging at 12V). You could also put 2 lynxmotion 2800mAh 6V packs together in series to make a 12V pack. But one caveat… you need to charge each 6V pack separately as they may have different peak charge levels.
Richard
I see about the batteries…I will do some research on those.
About the motor controller: It’s awfully expensive…does anyone know of something a little cheaper? :EDIT: Because, frankly, I don’t think I would use even a fraction of the features!
Thanks again!
theChipmunk
Good point Chunga… a motor controller (I like the Scorpion) would be much simpler and easier to implement than fussing with mosfets and solder.
Richard
plus depending on how expensive the mofset is, and 2 at just over how much a scorpian would cost, the motor controllers would probably never burn out because of its high capacity and plus they are just screw terminals, easy stuff 8)
… and you are less likely to have the pop goes the FET problem using a motor controller with integrated heat sink
Yes, I suppose so, but it is awfully expensive!
theChipmunk
yea, thats a downside, but how expensive are the mofsets that you would use for this?
Well, if THESE would do the trick, then £1.56 ($2.90) a MOSFET!
(Which, I think you’ll agree, is a lot less than the Scorpion!!!)
theChipmunk
well then…go with those…lol 
Yes, but the scorpion has 3 channels + built in mixing. Just making a point, but use whatever you need chipmunk 
I don’t suppose that anyone knows of a really good tutorial on how to make your own H-Bridge?
I think it’s pretty simple, actually - just 4 MOSFETs on a board with a bit of wiring in between.
The difficulty for me will come with trying to decide if/what resistors etc I will need so I don’t fry everything… 
theChipmunk
Thats some really advanced stuff.
