Power considerations for motor shield (Total newbie)

hello everyone, am starting to venture into the specific topic sections after dabbling mainly in the "General Electronics" and "Programming Questions" ones.

i have an Arduino Uno with a Motor Shield (1A, based on L293B chip); http://www.dfrobot.com/wiki/index.php/Arduino_Motor_Shield_(L293)_(SKU:_DRI0001)

i'm using a pair of old DC motors lying around which are rated at 9V and Max.consumption of 0.65A.

that current setup should be quite safe (workable) to use with a 9V battery to the Uno DC jack, right ?

my question is, the product wiki says; "The Motor shield is powered directly from Arduino." - does that mean that the shield takes the 9V for the motors from the DC jack, or that it takes only 5V which comes through that DC jack.

this is the schematic if it helps at all (for one who can actually read it !) http://www.dfrobot.com/wiki/images/3/31/Arduino_Motor_SCH.png

if it's not the 9V that is taken, what i understand is that connecting to the L293 chip directly, one can connect the external power supply to the Vin pin for that chip - how would one do that with the shield ?

I think that means that Vin is used as the motor supply and Vcc as the 5V supply to the L293

You should double check with a multimeter, hopefully there's a way to provide motor power separately from the Vin pin (not ideal).

from http://www.dfrobot.com/wiki/index.php/Arduino_Motor_Shield_%28L293%29_%28SKU:_DRI0001%29

"The Motor shield is powered directly from Arduino. It is strongly advised that use external power supply (on Arduino) to power the Arduino instead of the USB power supply."

clearly the power is from the Arduino.

the picture of the board shows a heavy track on the VIN pin.

dave-in-nj: ... ... the picture of the board shows a heavy track on the VIN pin.

i'm somewhat ignorant to what goes on on a PCB, could you explain what you mean by "a heavy track on the VIN pin" ? i can't see it being any different to the other pins (digital or analog)....

It is always a good idea to power a motor from a separate supply than the Arduino, if you can. Even if the Arduino power supply can handle the extra load of the motor (which is very often not the case), motors generate a lot of electrical noise and can cause the Arduino to malfunction.

MarkT:
I think that means that Vin is used as the motor supply and Vcc as the 5V supply to
the L293

Hello Mark, are you getting that from reading this ?

so, if i have understood correctly, the 9V comes from the DC jack, through the Arduino Vin and to the L293B “VC”
while the 5V comes from the Arduino 5V pin which is coming from the DC jack via the voltage regulator, and to the L293B “VSS”

MarkT:
You should double check with a multimeter, hopefully there’s a way to provide
motor power separately from the Vin pin (not ideal).

i checked the Voltage to the motor and it is indeed more than 5V, a little less than 9V - so the shield is passing the 9V from the DC jack to the motors.

jremington:
It is always a good idea to power a motor from a separate supply than the Arduino, if you can. Even if the Arduino power supply can handle the extra load of the motor (which is very often not the case), motors generate a lot of electrical noise and can cause the Arduino to malfunction.

i’m getting that is a good habit, even if this shield is rated at 1A and i’m using small DC motors.
to provide the separate supply, i’d have to connect it here, right ?