Let's Make Robots!

Motor driver design ideas

I've decided to rebuild my L239D based motor controller a bit since A) it looks like crap and B) it uses to many pins and C) can't handle larger loads.

The plan is to piggyback two SN754410 instead of one L239D and add a tristate switch with transistors for the HIGH/LOW part.


The first question I have now is although the SN754410 is pin compatible with L239D, can I just mount two on top of each other and get 2x1A?

And to the second question; will I need protection diodes and which do you recommend in that case?


Or do you have some other completely different idea? I want a really good motor driver. I intend to build two or maybe three to use in future projects.

 

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Although the legs are staggered the longer ones are quite flexible. I have used these in breadboards and projectboards without any problems. This photo is from my robot Pictomatix.

 

 

 

The pins are in 2 rows but the second row is offset to the first so it's not veroboard friendly. Sparkfun has a breakout board. $2.95 US. I'd then use the veroboard to mount the breakout board and any other parts needed.

Unfortunately my board really can't do too much more as far as the L293D is concerned but the pic is programmed so far to drive the l293d, spin the servo and read the sharp distance sensor. I've got all or nearly all the building blocks in place and am just stuck on a good algorithm for obstacle avoidance. I can't say I've fried an L293 yet. Maybe you should just redo your wires under the board and go with what you've got.

Have you seen my pic and l293d board. I put the wires underneath for a reasonably tidy look. I tied the enable pins to positive rail so it only needs 4 pins.

Piggybacking will work I have seen it done but I wonder whether it's truly doubling the capacity when you consider the heat that must get trapped between the two.

I always thought the sn754410 was without protection diodes but I was corrected on that. Funny they don't actually mention it as a feature in the datasheet I have but when you look at the equivalent output circuit it does show them there. Have you considered a L298?

I guess I could just mount it on a piece of veroboard and do my own "DIP-socket" :).

I've missed that board. Looks awesome! What can it doo that my "normal" controller can't?

Yes, I've considered an L298 and I think I'm going to go with that instead, not sure yet though. Do you know if it will fit in a DIP-socket? I want to be able to replace my circuits quick if they fry :)