arduino mega power supply

hi guys, i just have two questions if anyone can help me. i am using arduino mega 2560 to control 11 DC motors i believe all of them are 3v each. i am connecting them all to the arduino by Hbridge. at the moment i am stuck to what power supply i should use, i was going to use 9v battery and connect it to the Hbridge but some websites said that its not going to work. also i am going to connect the arduino to my laptop. and barely only 2 motors will work at the same time.
so my questions, would arduino mega be able to handle all of the 11 dc motors?
and what power supply should i use?

i've attached a photo of how i'll connect the motors to the hbridge.

thanks so much :slight_smile:

If the motors are rated for 3V you shouldn't be powering them from 9V!

The Arduino has a built-in 5V regulator so it can be powered from 9V. But, don't power the motors through the on-board regulator because it can't supply much "extra" current.

You need a 3V power supply, or a 3V regulator (or a little higher since there will be some voltage drop across the H-bridge). And, the power supply and/or regulator needs to be rated for the total current (A or mA) for all of the motors.

thanks so much for your help. so should i use something like that and connect it to my h bridge?


3volt motors draw more current than 12volt motors of the same size.
So current could be a problem.
A 6volt AA battery holder won't cut it. It could melt from the curent of 11 motors.
Assuming the AA batteries are not collapsing under that load.

I would power the Mega from a 5volt cellphone supply, connected to the USB socket.
And VCC2 pin of the L293 chips for 3volt motors from a beefy 5volt supply (>=5Amp).
Assuming you want to use H-bridges, to be able to forward/reverse the motors.

Hey wawa thank you!!

I am kinda lost, do you mean connect the mega with something like that

And make it at 5v?

Perhaps ensure instead that the beefy 5v supply is just a little bit beefier, and thus power the Mega via the USB socket as well.

Should i get that and connect it to mega?

You ideally need TWO supplies. One for the Mega, and one for the motors.
Motors generate a lot of noise, so it's best to power them from a separate supply, rated for 11 motors.

The Mega can be powered with a tiny 5volt >=0.5A cellphone supply.
Everyone has several of them around the house.
Use one with a USB socket, so you can plug in the USB lead of the Mega.

Forget about that supply with the selector switch.

If you go for the Adafruit supply, then also order an adapter with it, so you can use wires to the L293D chips.

The short answer is no.
There are probably cheaper power supplies that are more appropriate. You need to separate the supplies between motors and Mega, and it may actually be simpler, even if most inelegant, to use an old phone charger as suggested above.
The long answer is that 50 watts is 50 watts and, if that is more than your calculated need, then this has got them , and it can be pursuaded to do the job. It is a matter of getting power to the motors, and the pursuasion may include the use of a soldering iron, and adding other stuff.
The job of the Mega is to control the other gear, not drive it and, as far as power supply is concerned, Mega is the least of your problems, and is really just going along for the ride.

Guys thanks so much!!!

So what i was thinking of doing!
Is to connect the Hbridge to power supply module that came with it and connect that to an adapter at 5v.

And since i’ll be connecting the mega to my laptop, do I still need to connect it to a power supply?

And if any suggestions for what should I purchase as power supply for H-bridge?

And i am really sorry if my questions sound dumb, i am new to all of this so that’s why

Breadboard supplies are heavily overrated.
They state 12volt and 700mA, but they don't tell you you can't do that at the same time.
They need a minimum of 6.5volt on the DC socket, and might be able to do 700mA at that input voltage for a short time (before releasing the magic smoke).
Could be ok for two small motors, but not for 11.

If you connect the Mega to a PC, then you just need a supply to power the motors.

Those little 3 volt motors, about an inch long, 2mm or less, round shaft, spin real fast, and cost a dime for a dozen, right? They draw 25mA or so when running unrestricted full speed at 3 volts. When you start a heavy load from a dead stop, it can draw 2 or 3 amps. Multiply that all together with how many motors will be running at the same time, and there is an estimate of the power you will need.

I especially like that you said you were gonna run it all with a 9 volt battery, and nobody yelled at you. That shows that we are growing as a collective.

I hope OP doesn't mean 3volt drone motors :o .
They could draw 5-8Amps running, and 30Amp on startup (each).

Thanks guys!

Alright got it! Any power supply suggestions that i can buy? Since I can’t use AA batteries.

And this

Connected to the power supply model won’t work?

Did you see the 1.2Amp rating?

Hmm is there an adapter or a battery that i can buy that would give 3v and 8+Amp?

You don't want a 3volt supply for your (unspecified) 3volt motors, because you're using an L293 H-bridge.
That ancient H-bridge drops 2-4volt, depending on motor current (2.4volt typical @ 600mA), leaving about 3volt for the motors if you use a 5volt supply.

Oh!!! I see!! Omg! Thanks so much for this explanation, makes so much sense!

Do you think that is a good one?

@Flobater, do not cross-post. Other thread removed.

Don't know if that 5volt/15Amp is just ok or overkill, because you didn't post a link to the motors yet.