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Topic: How to supply enough voltage to control 4 servos and 3 joysticks. (Read 520 times) previous topic - next topic

GreenYeti

I am currently working on a project in which 4 9g Servos are going to be controlled by 3 joysticks (one of the joysticks will control 2 servos). But the normal 5v/VCC pin of my Arduino is not enough to power them all so the servos just vibrate. What should I do? I saw somewhere that a 9v battery can be used instead of the Arduino 5v and if so will that be enough to power this project? I only have a battery holder that can hold 4 AA batteries, will that be enough? If neither will supply enough energy on their own will using them both cause harm to my Arduino or any of the components.

AWOL

Current will more likely be an issue than voltage.

A nine volt battery is a terrible choice.

Four AAs with a common ground is a good starting point.

slipstick

4 x NiMH rechargeable AAs connected to the servos and the 5V pin will do the job nicely. You could use the 9V battery just for the Arduino but it's not necessary and they're useless for servos or motors.

Steve

GreenYeti

I give my thanks for the answers! But, I am a complete novice in electronics and would like to ask what you meant by common ground?
 

GreenYeti

4 x NiMH rechargeable AAs connected to the servos and the 5V pin will do the job nicely. You could use the 9V battery just for the Arduino but it's not necessary and they're useless for servos or motors.

Steve
When you mean AAs connected to servos and the 5v pin do you mean that the VCC should supply the power for the joysticks and the 4 AAs should power the servos?

I also thank for your answer!

slipstick

Possibly. What Arduino are you using? None of mine have any pins marked VCC.

I mean you can power everything from 4 x NiMH batteries by connecting them to the servos AND the Arduino 5V pin AND anything else you have.

Steve

GreenYeti

Possibly. What Arduino are you using? None of mine have any pins marked VCC.

I mean you can power everything from 4 x NiMH batteries by connecting them to the servos AND the Arduino 5V pin AND anything else you have.

Steve
Thank you! I meant 5v on the Arduino when I said VCC

I have gotten a setup to work, however(perhaps this issue is only for me) my servos seem to warm up really fast, in about 30 - 45 seconds of use they get noticeably warm, is this a problem or is it something I should worry about? If so is there a way to cool them whil still keeping them in use. 

jremington

Most hobby servos are designed for intermittent use, and will burn out if they run continuously, especially against heavy loads.

What are your servos doing?

GreenYeti

Most hobby servos are designed for intermittent use, and will burn out if they run continuously, especially against heavy loads.

What are your servos doing?
That may be the case, my servos are moving about pieces of plastic that are screwed together to make an arm. The servo at the bottom rotates the entirety of the arm while two servos are moving the arm up-down and right-left and a final servo is controlling two pieces of bent plastic which can(when code is run through) grasp things by coming together and drop them by moving apart from eachother.

slipstick

I have gotten a setup to work, however(perhaps this issue is only for me) my servos seem to warm up really fast, in about 30 - 45 seconds of use they get noticeably warm, is this a problem or is it something I should worry about? If so is there a way to cool them whil still keeping them in use. 
How exactly did you get the setup to work? If you ended up with more than 5V to those servos then that would explain something.

The problem with robot arms is that the servos are always loaded. Even when you're not moving them they're working to support the weight of the arm. Unless you have really small lightweight components those tiny servos may simply be overloaded. Swapping them for better servos like MG90s might help but it depends what weights you are expecting them to move/support.

Steve

GreenYeti

How exactly did you get the setup to work? If you ended up with more than 5V to those servos then that would explain something.

The problem with robot arms is that the servos are always loaded. Even when you're not moving them they're working to support the weight of the arm. Unless you have really small lightweight components those tiny servos may simply be overloaded. Swapping them for better servos like MG90s might help but it depends what weights you are expecting them to move/support.

Steve
I do not think it is the overload of voltage. It may be that too much weight is being put upon them, I will check the servo you sent.

GreenYeti

Okay so there is also another problem. I think the servo's do not have enough power to move the arm, possibly do to excessive weight or lack of power. I had tried the 4 AA battery idea and connected it to the negative and positive lanes of the breadboard however when I tried it the arms movements were inconsistent and the majority of the time it did not move although the servos did vibrate.

A similar type of vibration was also present when I did not use the battery and only the Arduino 5v.
However, I am pretty sure my wiring is correct as the arm did work when only 2 servos were being controlled via one joystick.



What am I doing wrong?

slipstick

Difficult to say what you're doing wrong when we can't see what it is you're doing. Pictures of the arm and the rest of the setup might help and so might the code you're using if you post that. You can see what you have but we can't.

Are you using the rechargeable batteries I recommended? They can supply more current than standard 1.5V consumer AAs.

Try connecting the servo power directly to the battery NOT through a breadboard. Many breadboards can only handle low currents like joysticks and the Arduino. Those servos need up to 650mA EACH.

Steve

GreenYeti

Difficult to say what you're doing wrong when we can't see what it is you're doing. Pictures of the arm and the rest of the setup might help and so might the code you're using if you post that. You can see what you have but we can't.

Are you using the rechargeable batteries I recommended? They can supply more current than standard 1.5V consumer AAs.

Try connecting the servo power directly to the battery NOT through a breadboard. Many breadboards can only handle low currents like joysticks and the Arduino. Those servos need up to 650mA EACH.

Steve
I will not be able to buy your recommended batteries, however I will attempt to connect the power directly to the servos, by any chance can that harm the servos.
 

GreenYeti

I changed the arm to a setup of only three servos controlled by 2 joysticks, and it is doing fine but occasionally it stops or begins to vibrate again. I was thinking if I connect 2 servos to the Arduino 5v+
(which is powered by my computer) and connect one servo to a pack of 4 AA(each of 1.5 v). Will doing this harm my servo, computer or Arduino?


Thanks for all your replies and spending your time to write them!

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