Let's Make Robots!

Motor going backwards?

So I bought myself a couple of motors today at Radio Shack, however I'm not exactly sure how they would work to go backwards.

I'll be hooking them up to my picaxe once my motor controller gets here, but until then I'm just playing with them on my breadboard.

Does the controller change the current in order to make the motor go backwards? My motors only have two hookups, positive and negative, none for sending a signal to it.

Here are the motors I got:


Any help would be much appreciated.


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Sounds like you have regular DC motors. The +ve and -ve are misleading. They might be better labelled A and B! The motor controller is what's known as an H bridge. (Because the schematic looks like an H with the motor in the middle.) What it does for you is to reverse the polarity of the two output lines, so to get it to go "backwards" (a relative term), it connects the _ve voltage to the -ve terminal and vice-versa.

Try it. Swap the wires. 

Ah! You're right. Bravo! Thanks Base!

I'm only wrong when jip questions me.

Just bear in mind that this doesn't work for servos. For Heaven's sake don't connect them up backwards, or else all the special blue smoke will come out and it's expensive to get a wee man to put it all back in again.

"Does the controller change the current in order to make the motor go backwards?"

Yes :) 


Awesome. So then I'll just stick with these motors :)

Uh, but the motors you link to is not geared!!

See topic about it somewhere :) You need gearing!!

Here's the thread about it.


Looks like I'm gonna have to order some then!

I'll see what I can find a little bit later tonight.