servo mod

Last night I decided to modify a couple of the standard size servos I had laying around to function as continuous rotation gear motors. The servos are Futaba S3003 from a model airplane that I built in high school that was damaged beyond repair. I havent built any more large model airplanes so I have these laying around.

This mod was focused on the final gearm so that it would no longer engage the potentiometer. The pot gives rotation feedback to the servo circuitry.

*After disassembly a notch was cut into the top of the pot with a dremel so that the pot could be turned with a precision standard head screwdriver.

* After this the tab on the side of the final gear was removed so that it no longer engaged the stops built into the top of the case.

* the bottom interior of the gear contains posts to engage the pot. These were removed with a 5/32 drill bit.

* the hole from the top was also reamed out with a 5/64 bit so that a precision screwdriver could fit through the gear. This allows adjustment so that the pot can be set to the neutral position.

Once the servo was reassembled I hooked it up to the arduino on one of the PWM pins. I then used the following code so that I could adjust the pot to neutral where the motor is stationary.

#include servo.h

Servo myservo;

int pos = 90;

void setup()

{

myservo.attach(9);

}

void loop()

{

myservo.write(pos);

}

This mod allows the servo to be used like any other motor using PWM output at 5v from the arduino digital I/O pins.