Higher current motor driving

[simcop2387]

I'm wanting to build something for driving a higher current motor, specifically an HO train set. Some measuring puts it at about 0.75A @ 20.5V under load (train with lots of cars). I believe I'd like to do 1A continuous at 24V (just because it's a more "round" number) and 2A peak for safety.

I'm basically wondering if anyone has any advice as far as an existing driver chip that might be able to handle this kind of load without too much trouble. I know that some people will stack L293Ds but I'd rather have something that I'd feel is a little more suited to higher loads. Ideally I'd like to also do it with PWM rather than varying the voltage.

[philba]

There is a polulu controller that looks like it might meet your needs - assuming brushed motors. http://www.pololu.com/catalog/product/1394 I don't know anything about it other than whats on their page, though. There are several others on that site that might work and are cheaper, though.

[simcop2387]

Yes it's a pretty good bet that the motors will all be brushed motors. It certainly looks like it'd exceed the current requirements but is more than I'd like price wise because it's got so much other stuff on there that I won't need. I've got no problem building something with an L293D or some other H-Bridge myself, but I'd love if it had some built in kickback-diodes for the simple fact that I'm not 100% sure the correct way to put them in for a bidirectional setup.

[adafruit_support_bill]

Stacked L293D's or a SN754410 will handle the 1A continuous/2A peak. You could even stack SN754410's for a bit more headroom. (I've run G-gauge trains with that configuration.) I generally build up the motor shield with a clip-on heat-sink for the H-bridge chips too.

Keep in mind that the L293D has 4 half-bridges which are typically configured as 2 full H-bridges. With 2 L293D's on the Motor Shield, you can run as many as 4 track-blocks simultaneously.

The Motor Shield speed control is via PWM. There are some 'coreless' motors that don't work well with PWM, but I don't know if they are used in HO.

[wb8nbs]

I used a Polou MD01B controller for an automotive power seat motor (2 amp normal draw). It was less than $30 and handles PWM.
Suggest you look around the Robotics suppliers. There's lots of them.