i want to use arduino to control a servo to make a heading indicator for my flying sim cockpit . i modified the servo to run continously. to get the right heading i have to control the servo through the signal wire and the servo potentiometer which i mounted it outside the servo, controlling the signal is an easy job with arduino , but i want to control the current in the potentiometer circuit instead of controlling the potentiometer itself with another servo
If I'm understanding you right, you can just use a digital potentiometer, which works almost the same.. except it's on a chip, and needs to be controlled via the Arduino.
But I'm curious, what's the voltage that's going through the potentiometer? I'm not sure, but you MAY be able to use PWM to modify what voltage you're sending into whatever the input is.
I believe there are some motorized potentiometers, which you can control with just a voltage on the motors. Used for like, some home stereos and such. (most use encoders now days I believe)
How does your "heading indicator" circuit work? Is it a mechanical meter? A digital readout?
You may be able to just use PWM (perhaps with a few external parts) to generate the signal you need, but you you need to give us some more hints about it.
Ran
i'm taking the heading out of my X-plane simulator through a python plugin feeding arduino to move the servo , i need the servo to move with resolution of 144 steps ,2.5 degrees for each step so i think i can use 8bit digital potentiometer,nt the servo is running on 5v, with max current of 60 mA, i dont know if digital potentiometer will handle that current cause i saw in some digital potentiometer datasheets the maximal current in microamps and i will also give PWM a go
Um, it appears that you didn't answer the crucial question: what signal does the actual "heading indicator" need? Is it a meter? Is it a servo, itself?
If it needs an analog current of less than about 100mA, you could use a very simple opamp circuit to amplify the signal from a digital pot or a PWM output to drive it.
But we need to know exactly what you need to help you figure out how to get it.
Ran
i'm trying to make a heading indicator ,the heading indicator is just a modified servo for continuous rotation which should rotate a circular chart a complete circle in 144 step (2.5 degrees/step). i want to control the servo to indicate the correct heading every 500ms
i know that servo are controlled by signal wire and sense the position by potentiometer position , i want my arduino to control the servo by the signal wire and simulating the potentiometer to use them in relation to each other to correlate the heading
simply i want to control the servo like a step motor
Personally, I'd consider replacing the servo with a stepper.
If you don't, to get position feedback, you probably want to attach some sort of encoder disk to the motor. Perhaps by printing radial stripes on the back of the chart and mounting reflective optical sensors next to the motor. This trick is use to get tach inputs from robot wheels driven by modified servos, so you might be able to buy something if it's difficult to make one.
Ran