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Topic: Servos with Monster Moto Shield  (Read 254 times) previous topic - next topic

McabralDS

Hi,

I need to connect 4 Servo motors (MG 995) for a project. I know that i can't connect into the 5v arduino. Can I use the Monster moto shield to control at least two of them?


AWOL

Quote
I know that i can't connect into the 5v arduino.
Why not?
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.

McabralDS

Each servo needs 140mA to work, I have 4 of them and they need to move simultaneously

AWOL

So?
Get a 560mA power supply.
Like four AA cells.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.

slipstick

The no-load current of an MG995 is 170mA, the stall current is 1.2A and they run best on 6V. I'd look for at least a 6V 5A power supply. 5 x rechargeable NiMH AAs might be o.k.

Of course you will connect the power directly to the servos. Only the signal wire connects to the Arduino.

And no, a motor shield will not drive servos.

Steve

PaulS

Quote
Only the signal wire connects to the Arduino.
Bzzzt. Wrong.

The ground wire needs to be connected, too.
The art of getting good answers lies in asking good questions.

slipstick

Or all servo ground wires need to be commoned with the power supply and Arduino grounds.

Amazing how often one forgets to state what should be obvious innit?

Steve

kenwood120s

Amazing how often one forgets to state what should be obvious innit?

Why should it be obvious to a beginner though? (Not that OP is necessarily one.) Sure, once you say something like "well you can't measure the voltage of a battery with only the red lead..." the penny drops, but the notion of needing a 0 for the Arduino to measure the signal against is not that obvious to all.

[gumby]I've got my head stuck in the cupboard[/gumby]

slipstick

Indeed. It was me I was criticising there. When you've known something for 50-odd years it starts to seem obvious, common knowledge even.

Perhaps you never have this problem but I certainly find that I sometimes forget to mention things of that nature. Must try harder.

Anyway I hope the OP has the main point...the red +ve wire from the servos should go direct to the power supply not to the Arduino.

Steve

kenwood120s

[gumby]I've got my head stuck in the cupboard[/gumby]

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