Go Down

Topic: Servo and Motor Driver incompatibility (Read 693 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.
Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   8)

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)

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.

Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   8)

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.....

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.

Go Up