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I have already made a diagram using a motor controller. I want to use only one power supply to feed arduino and motors. I want to use MDD10 dual motor driver.

The details of the actuators each one is:

Input voltage: 12VDC, Max Load: 750N(168.607lbs), Stroke Length: 16 inch, Travel Speed: 12mm/s, Duty Cyle: 25%, Current: 5A.

The power supply is 12V, 10A.

Could you please check if it is ok, or which would be the best solution?

Some of my concerns are:

Be sure if the feed of 12 volts for the motors, and 5 volts for Arduino are correct and can live together as shown.

Be sure if the wiring for the Arduino, driver and motors is correct since it looks kind of simple. enter image description here I want to know if this is the natural approach by doing it with a voltage regulator to feed the Arduino and with 12V 10A power supply to feed the motors, or if there are other, better options to make the circuit feed only using one power supply (12V, 10A).

MDD10 Datasheet Link: https://www.robotshop.com/media/files/content/c/cyt/pdf/cytron-10a-7-30v-dual-channel-dc-motor-driver-shield-datasheet.pdf

Thanks in advance

UPDATE

I have increased power supply to 13A, also changed the linear voltage regulator (7805) to a switching voltage regulator (OKI-78SR-5), what do you think about this approach? enter image description here Or I should try with the 12V DC Vin of Arduino(I understand that it works with a linear voltage regulator)? Being this option, it could be maybe with a voltage pre-regulation stage(for example from 12V to 9V) or maybe connecting directly to the jack. enter image description here Thanks, Best Regards.

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2 Answers 2

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First of all I would look to see if the two motors will actually run at the same time. If not then the 10A power supply, is fine. If they do run together, for how long? (you mention 25% duty cycle), power supplies usually have a over capability for a short period of time, and batteries will supply more current but at a slightly reduced voltage, so if going slightly slower isn't an issue then this would be fine. Then there is the question of do they really use all 5Amps, I very much suspect not, unless you are fully loading the actuator(750N), they prob run at 2-3 amps at most. Secondly Circuit protection, fuses or thermal shutdown links for the motors is required, better still instant overcurrent protection for them set at 1.2x nominal current. Do some worst case tests and measure the current, set the protection to 1.2 x this. Remember if there is an issue the supply voltage will start to drop, its now that the micro will suffer if the voltage dips too much and you have no protection/sensing.

So suspect the power supply is more than ok.

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Your approach looks reasonable, but you don't have enough power. The motors will draw 10A, which is the full output of your power supply/battery. That doesn't leave any left over for your Arduino system.

You should have a high enough capacity power supply/battery for your total peak power requirement plus a little margin (say 10%-20%) The Arduino and all the other electronics on it might draw another 1/2 amp, so 10.5 total. Add 20% margin to that and you get 10.5 * 1.2, or about 12.6 A.

(When you drive a power supply up to its upper limit its output voltage can start to sag. By having a buffer it doesn't have to work as hard.)

One advantage you have in your circuit is that you're feeding unregulated 12V to your motors, and then feeding 12 into your Arduino's voltage regulator. That way even if the 12V supply droops to 10V under maximum load, the voltage regulator will still be able to maintain a clean 5V supply to your MCU.

Also note that you could feed 12V into the Arduino's V in and use its built-in voltage regulator. As long as don't draw a lot of current out of its 5V line the built-in regulator could manage the 5V voltage regulation itself. If you need ≥500 mA, though, you might want to use an external buck converter (or a high capacity linear regulator with a good heat sink.)

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  • Hello Duncan C. So what I understand is that the circuit I show could connect it directly to the 12-volt arduino jack because I don't need much current. And only If I need more current for an extra element that is connected to arduino output, I would need a buck converter or high capacity linear regulator to increase amperage. Did I understand correctly? Could you give an example when I need a buck converter, What exactly is a buck converter/high capacity linear regulator? Thanks
    – punk code
    Commented Sep 17, 2019 at 0:33
  • The Arduino uses a linear voltage regulator. A linear voltage regulator is an analog circuit that uses a transistor to apply a variable resistance to the input voltage to lower it down to the output voltage. It converts the excess voltage to heat, so at high source voltages and current loads it gets hot. A buck converter is a type of switching power supply that instead uses pulses of current to regulate the output voltage. Buck converters are more efficient, and don't create as much heat at high current loads.
    – Duncan C
    Commented Sep 17, 2019 at 12:47
  • If you're just powering an Arduino and a few components, you won't be using much current, so the built-in linear power supply in the Arduino will be fine. If you need ≥500mA of 5V, the Arduino's power supply will start to get hot, and as you get up to 1A, it may even overheat when fed from a 12V supply.
    – Duncan C
    Commented Sep 17, 2019 at 12:50
  • Hey @Duncan, Greetings. I have updated my question. I changed the schematic by adding a switching regulator, instead of the linear regulator. I am also referring to the option to connect directly to the 12V jack of arduino. Could you please check it? Thanks
    – punk code
    Commented Sep 17, 2019 at 21:06
  • Same problem. You don't have enough power. You want your power supply to provide a little MORE current than your max need, and your 10A supply is less, not more. Boost the battery/power supply to ≈13A and you should be good.
    – Duncan C
    Commented Sep 18, 2019 at 2:16

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