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I got a 6 AA cell pack. So I can basically get 8.2V.

I need to power an Arduino and 2 DC motors driven by a L293D.

My Arduino can accept 7V to 12V DC input and the L293D between 4.5v to 36V.

Can I simply deviate another line from the cell pack and feed the L293D with it? I want to do that because the load of the two DC motors can quickly be around 200mA/motor, the 5V input is 500mA max, I've got other things to feed with (one servo, an IR sensor, some leds and two other sensors) so I can quickly be higher than 500mA.

Something like this:

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ I don't want to be rude or anything, but I just wanted to let you know that the correct part number is L293D and not L239D like you've been posting in a few of your questions. \$\endgroup\$ – Ricardo Dec 30 '13 at 2:40
  • \$\begingroup\$ @Ricardo : Yeah sorry I know, I just figured out that some days ago. I invert the two (old rest from dyslexia ? :p) and to help me a lot of people on the web do the same mistake (look at l239d or l293d on google). I will be more careful in the future. \$\endgroup\$ – Emmanuel Istace Dec 30 '13 at 5:43
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Yes, you can have multiple devices hanging off the same pair of supply rails.

You should not have multiple ground paths though - like the ground-to-ground connection shown between the Arduino and the L293D in the diagram. Ideally, all the devices should connect to each other and the supply ground at a single point, to avoid ground loops.

Also add hefty capacitors (10 to 100 uF) between Vcc and Gnd pins of each device to decouple the supply.

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Yes. You can connect the line from cell pack to the pin Vs in L293D.

If you are only planning to connect the 5V from Arduino to Vss of L293D, then it is fine. But in future if you are planning to connect servo motors, IR sensor etc. then it is not recommended. Servo motor will consume more current.

It is recommended to use an additional 5V voltage regulator(7805) which has 1A current capacity. Feed the servo motor from that regulator.This will avoid the damage of the voltage regulator in the Arduino.

Replacing the 7805 IC is much easier that replacing the regulator on the Arduino.

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  • \$\begingroup\$ These will be connected directly to the 5V output of the arduino as they don't draw so much current. (150mA in total). \$\endgroup\$ – Emmanuel Istace Dec 22 '13 at 5:29
  • \$\begingroup\$ @EmmanuelIstace Then your circuit is fine. \$\endgroup\$ – robomon Dec 22 '13 at 6:21

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