Satellite Dish linear Actuator

[ptonsparky]

I have a couple Linear actuators from old Sat dishes. One gives 32 pulse per inch of travel the other a pot.

The one I am curious about has a variable resistor (Pot) to give position feedback I remember similar for damper positioning. Operator would turn control to set the damper and the damper would open or close until its reached a similar resistance or position to the operators.

I'm looking for a diagram and/or the logic.

Who remembers such an animal?

 

[hbiss]

Sounds like a job for a PLC.

-Hal

 

[ptonsparky]

Sounds like a job for a PLC.

-Hal

Yes. Today for sure.
I thought it might give me a simple logic to start with. Sometimes I make things harder than they should be.

Okay, oftentimes.

 

[Jraef]

The one with the pot likely has an LVDT (Linear Variable Displacement Transducer) inside of the actuator that detects distance and direction of travel of the cylinder inside. So the simple feedback loop is that the user sets the pot to a voltage value that represents a percentage of the full travel, the actuator moves until the feedback from the LVDT matches that value. It’s crude and not terribly accurate (meaning the pot), but simple and LVDTs are very robust.

Position & Displacement Measurement with LVDTs

This white paper describes LVDTs and explains how they measure position & displacement. Read the full paper at ni.com.

www.ni.com

 

[ptonsparky]

Maybe I shouldn't call it linear. The end goes out linearly, but moves via a screw shaft. Small motor turns the shaft to a selected length.

 

[ptonsparky]

Business end . No, I did not keep the controller .

 

[ptonsparky]

Replace the LVDT with the pot pictured above and I'm good.

Replicated with a PLC.

I think I'll make a very slow Al can crusher out of it.

 

[kwired]

The one with the pot likely has an LVDT (Linear Variable Displacement Transducer) inside of the actuator that detects distance and direction of travel of the cylinder inside. So the simple feedback loop is that the user sets the pot to a voltage value that represents a percentage of the full travel, the actuator moves until the feedback from the LVDT matches that value. It’s crude and not terribly accurate (meaning the pot), but simple and LVDTs are very robust.

Position & Displacement Measurement with LVDTs

This white paper describes LVDTs and explains how they measure position & displacement. Read the full paper at ni.com.

www.ni.com

I think he is asking the logic of how modulating damper/valve actuators and such that use some sort of balancing circuit for control work. Many of us know it is seeking balance by turning output shaft until it reaches the right spot to balance the resistor network used for control but don't know what actually makes it do it's thing in the controller as it is all incorporated into the circuit board on the controller, which is inside the actuator motor assembly in most cases and all you do in the field is run three wires to the control pot or you sometimes may just short the wiper lead to either end in situations you wish to drive the output to either end of range of travel.

 

[ptonsparky]

& MDSW asks me what I been doing.

 

[ptonsparky]

 

[ptonsparky]

Can crusher.
Not done yet .
The joys of misc good stuff and time to spare.

 

[kwired]

Looks like you are having fun with your retirement.

My wife always asks me why I keep a lot of the "junk" I have - need something to play with someday I guess. Right now only experimentation with anything comes from a current necessity situation.