Potentiometer feedback tells you where the actuator is by changing voltage as the actuator moves. That voltage only helps if you know the stroke, the feedback voltage range, and the controller input. Read it wrong and the actuator position will look precise while the math lies to you.
What is potentiometer feedback?
Potentiometer feedback uses a variable resistor connected to the actuator motion. As the actuator extends or retracts, the feedback voltage changes.
What is the simple explanation?
Think of it like a fuel gauge for actuator position. Low voltage means one end of travel. Higher voltage means farther along the stroke.
Use the formula below to estimate position.
Position = ((feedback voltage - minimum voltage) ÷ (maximum voltage - minimum voltage)) × stroke
What should the calculator inputs be?
Use this as a first-pass sizing tool. Then confirm the final choice against the actual FIRGELLI product page, the wiring diagram, and your real mounting geometry.
"Potentiometer feedback only tells you the truth if both ends are calibrated and the signal wiring stays clean. A noisy feedback line will make a controller chase a position that was never real."
How do you use this calculator?
- Enter the real project values, not guesses from a different mechanism.
- Use measured current, load, stroke, voltage, or signal values where you can.
- Add margin for real brackets, wiring, friction, and installation conditions.
- Click Calculate to see your result.
What should you check before wiring feedback?
Check the actuator feedback type first. Potentiometer, Hall effect, and optical feedback do not behave the same way. A controller that expects pulses will not read an analog potentiometer like a voltage divider.
Run signal wires away from high-current motor wiring where you can. Noise in the feedback line makes the controller chase false position readings.
What is a simple example?
A 12-inch actuator reads 0.5V retracted and 4.5V extended. At 2.5V, the ratio is (2.5 - 0.5) ÷ (4.5 - 0.5) = 0.5.
Position = 0.5 × 12 = 6 inches extended.
Recommended FIRGELLI setup
Which FIRGELLI products fit this job?
Choose feedback hardware from the signal your controller can actually read.
Feedback Rod Linear Actuator
Use this when the project needs actuator position feedback built into the actuator body.
View Feedback Rod Actuators
Linear Potentiometer
Use this when you need an external linear position reference for a mechanism or test setup.
View Linear Potentiometers
FCB-2 Actuator Controller
Use the FCB-2 when you need controller features around feedback-based motion, presets, or synchronized actuator control.
View the FCB-2For actuator basics, start with the linear actuators guide.
Where is potentiometer feedback actually used?
- RV and smart furniture: Matched-position synchronization between two actuators on a slide, lift, or platform.
- Marine hatches and covers: Holding a repeatable open angle without relying only on end-stop limits.
- Industrial automation: Driving a mechanism to multiple preset positions instead of just fully extended or fully retracted.
- Medical and lab equipment: Returning a moving stage or arm to the same position after power cycles.
- Custom motion projects: Closed-loop control where the controller adjusts based on actual position rather than open-loop run time.
What are common mistakes when using this calculator?
- Skipping calibration of both ends. If retracted voltage and extended voltage are guessed instead of measured, every position value is wrong.
- Using the wrong feedback type for the controller. An analog potentiometer signal will not be read correctly by a controller expecting Hall-effect pulses, and the calculator output will not match real motion.
- Ignoring electrical noise. Running signal wires alongside high-current motor leads can cause jumpy readings that look like real position changes.
- Plugging in nominal stroke instead of actual stroke. Real installed stroke can be limited by mounting, brackets, or end-of-travel hardware.
- Trusting the ratio outside 0–100%. Voltage outside the calibrated min/max means broken calibration or wiring, not extra travel.
How can you verify the calculator output is reasonable?
- Measure physically. Extend the actuator partway, measure the rod travel with a ruler or caliper, and compare it to the calculator's position value.
- Confirm the endpoints. At fully retracted, the calculator should read near 0 in. At fully extended, it should read near the full stroke value. If not, recalibrate the min and max voltages.
- Check the ratio. The feedback ratio should always fall between 0% and 100%. Values outside that range mean the calibration or wiring is wrong.
- Sweep the full stroke. Move from fully retracted to fully extended slowly. The voltage should change smoothly, not jump.
- Cross-check with the controller. If using the FCB-2 or another feedback-aware controller, compare the controller's reported position to the calculator output at the same voltage.
