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Topic: Servo and Motor Driver incompatibility (Read 706 times) previous topic - next topic

Murray_Bro

Dear Forum,
I have been using an Arduino Uno and a Critical Velocity 15 Amp Bidirectional PWM Motor Speed Controller to control a 12V 10 AMP motor. Things have been running perfectly until I added a SparkFun Large Servo to the Arduino.  Now the motor will not run in reverse.   SparkFun suggests a separate power supply for the servo or noise filtering. 
I have a robust 12V power supply for the Motor Controller.  Rather not add another 5V supply for the servo. 
Any suggestions on how to add the servo without throwing a wrench in to the soup?   Greatly appreciated.

Chagrin

This sounds like a code problem. Did you include the Servo library in your code? On a non-Mega Arduino that will disable PWM on pins 9 and 10.

zoomkat

Quote
Rather not add another 5V supply for the servo.


Well, direct 12v to the servo may kill it, and the arduino is usually inadequate to power a servo itself. You might power the servo via a 7805 regulator chip connected to the 12v power supply.
Google forum search: Use Google Advanced Search and use Http://forum.arduino.cc/index in the "site or domain:" box.

JimboZA


You might power the servo via a 7805 regulator chip connected to the 12v power supply.


As they might say on 9gag... "You make a suggestion like that on this forum and you gonna have a bad time"  8)
Arduino ethernet server here.... http://jimboza.gotdns.com:8085/

No PMs for help please

zoomkat



You might power the servo via a 7805 regulator chip connected to the 12v power supply.


As they might say on 9gag... "You make a suggestion like that on this forum and you gonna have a bad time"  8)


Not sure why. I've had a pair of web cam pan/tilt servos powered like below 24/7 since 2004 without any issues.

Google forum search: Use Google Advanced Search and use Http://forum.arduino.cc/index in the "site or domain:" box.

Murray_Bro


This sounds like a code problem. Did you include the Servo library in your code? On a non-Mega Arduino that will disable PWM on pins 9 and 10.

I believe I have cleared the code.  Sketch runs fine with servo control lead disconnected.  I did include the library in the code.
I also ran a sketch with only the servo code and that runs fine.

Murray_Bro



You might power the servo via a 7805 regulator chip connected to the 12v power supply.


As they might say on 9gag... "You make a suggestion like that on this forum and you gonna have a bad time"  8)


Could you elaborate on that please?

JimboZA

Some members are "against" regulators like that because they waste power.

In a 7805 style regulator, the input current is always the same as the output current, so since it's at a higher voltage, the difference in input - output voltage, times the current, is the wasted power in watts.

That waste manifests as heat.....
Arduino ethernet server here.... http://jimboza.gotdns.com:8085/

No PMs for help please

Murray_Bro


Some members are "against" regulators like that because they waste power.

In a 7805 style regulator, the input current is always the same as the output current, so since it's at a higher voltage, the difference in input - output voltage, times the current, is the wasted power in watts.

That waste manifests as heat.....

Thank you JimboZA.  Would you agree that it is a power problem and not a noise problem ?  Do you have a alternate recommendation from the 7805 regulator?
Thanks again for your assistance.

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