Powering the adafruit motor shield

Hi :) I've got 2 simple and short questions:

1) I want to power the shield via external power source and the board by usb. For this reason I've got a 9V 2000 ma adapter with a 2.1mm barrel jack, centre pin positive. Unfortunately the shield needs 2 wires not a barrel jack. Could I use this adapter to power it? What did you use to power your shield.

2) I don't have the adapter yet. But I have got the shield and two 350ma per coil stepper motors. Can I power the board and the motor shield via the barrel jack of the arduino? Is there any limit to what I can draw from the barrel jack?


Hi, Best advice DON'T ever power any motor or servo from the Arduino, you can't take much current out of the on-board reg, if you do you will get a voltage drop and the arduino will just keep resetting itself..

That adaptor looks fine, if the shield is that thing?? that has 2 x L293's (drops about 2v on output) it has a very strange way of working!! I don't like it! had one dumped it, etc... Adafruit seem to make a few shields, so just which one is it??

I now only use FET based modules, that DO NOT lose the power that the L293 does, also I don't like motor shields that use their own library, I find it limitting, and while I struggle a bit with C, I still prefer to write my own code.

I have build a few robots see here: www.melsaunders.co.uk under Electronics, But still have to use stepper motors for accurate turns and drawing, etc.

Hope it helps, regards.


I agree with Cactusface. You never want to power motors or servos from the Arduino regulator. And, you always want to be sure you have flyback diodes across any coil. (Motors, relays, solenoids, etc.) The L293 does not have them built in, so be sure to add them in your circuit.


Unfortunately the shield needs 2 wires not a barrel jack.

So ? What's the problem ? Are you afraid to cut the plug off ? (you can always solder or crimp it back on using butt-splices BUTT CONNECTORS

Ok it seems you got things a bit wrong here.
1) I’m talking about the second version of the motor shield.
It does NOT have 2x L293 but 4x TB6612.

2) It says in the manual that you can use the barrel jack to power the shield.

If you would like to have a single DC power supply for the Arduino and motors
Say a wall adapter or a single battery pack with 6-12VDC output, simply plug it into the DC jack on the Arduino or the 2-pin power terminal block on the shield. Place the power jumper on the motor shield.

It also had a schematic and i don’t think the shield uses the regulator (picture below)

So ? What’s the problem ? Are you afraid to cut the plug off ? (you can always solder or crimp it back on
using butt-splices [BUTT CONNECTORS](http://www.elecdirect.com/catalog/crimp-wire-terminals/butt-splice-terminals?gclid=CjwKEAiA9KymBRD6g6iOvv2joU0SJAB0vRQy97N7_83mOUDyPEf5Do0CycxNrdCWTYn04TrFnjWY-


Actually thats a really good idea! Im really new to electronics but Im a bit disappointed I didn’t think of that myself :smiley:

By the way: I want to use the shield with a due, which means I have to configure it to 3.3 V logic levels. Has anyone done this, or seen a tutorial?

The problem with that is the motor shield power jumper is designed for use with an UNO that has a 5V regulator so it won't work with a DUE that only has a 3.3V regulator. You must move the jumper to the 3V side.