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Asked — Edited
Resolved Resolved by thetechguru!

Continuous Rotation Servo Powered Externally


So I've been battling with maths recently and trying to figure out the torque required to shift my robot. I've got some on order but they'll be a month or two before they arrive. In the meantime, I'm thinking about using a pair of modified servos. However, I'm conscious of the power draw and figured with me already having a working set of H-Bridges on the chassis, I wondered if anyone has ever dabbled with powering (or even controlling) modified servos externally from the EZB? Am I bonkers to think that if PWM wire from the servo goes to the EZB as normal, and the ground is common, it will work? confused


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You can power anything externally from the EZ-B. Signal from EZ-B to signal on servos. Common ground. Power source to power on servo.



The red pin on the ezb provides power to your servos... If you want to you can power the servo with an external source by cutting the servo wire and disconnect the power from the red pin of the ezb . Replace that with an external + (positive) battery and connect the - (negative) battery to common ground...

However, there is absolutely no need to do this as the ezb can easily power modified servos and everything else through the red power pin (on the ezb)... Also servos have a built in H-bridge so you won't need an h-bridge to control them....

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@thetechguru and @Richard-R, thank you both. I thought this was the case but something made me stop and doubt myself blush


feganmeister, I am not sure of what you are powering with H-bridge already on your chassis. I would simply add continuous servo movement panel, and try it. Unless you are overloading, it should work. If you power servos from battery, use white signal wire. If you are still using your EZB3, I have used 8 to 10 standard (kit) servos plus serial communication at the same time with no issues. Steve S




If you power servos from battery, use white signal wire.
... Hmmm, that's not correct if you mean an external battery... when powering from an external battery you use the wire that would have went to the red pin on the ezb, not the signal pin wire... and then common ground with the other wire...

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I am not sure of what you are powering with H-bridge already on your chassis
Sorry @Steve-S I wasn't too clear; the existing H-Bridges are simply in place ready for the new motors, when they arrive. The modified servos are a temporary solution to give mobility. I'm not convinced the draw of the modified servos won't brownout the EZB - I'll go for external power just in case :)


I always thought the black was ground, red was 5 V +, and white was signal? Am I wrong? Hang on, I will take a picture.

Thank You, Steve S

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in your picture Black is ground Red is +5 white is signal

you got it right


Thank You Luis. I did not think I had too many? Steve S


@Steve, I understood what you were saying about the using the white signal wire from the servo.

@Richard, did happy hour start early, lol? ;)


@Justin What I read was that Steve seemed to suggest that you connect the external battery to the signal wire of the servo... I said that was incorrect... You attach the red power wire of the servo to an external battery.... It was open for interpolation I guess...

This is what Steve said....


If you power servos from battery, use white signal wire.

It looks like he was telling the op to connect the signal wire of the servo to an external battery, no?


Thank you Justin, In all fairness to Richard R, maybe I could have explained it more. Thank you, Steve S


I knew where you coming from too @Richard. I was just giving you a hard time :D :P