Alternating Polarity

Thread Starter

Lafish

Joined Feb 17, 2024
3
I’m looking for a device where every time my timer goes off, it will reverse the polarity of the connection to my dc motor thus extending and retracting a linear actuator. I would appreciate any help.
 

Jon Chandler

Joined Jun 12, 2008
1,099
I don't think this is going to work as well as you think. It's likely the linear actuator is going to drift out of position as the operating times in each direction will not be precisely the same, and even if they are, the linear actuator's travel vs time in each direction won't be exactly the same due to differences in loading, etc.

You need some kind of position feedback.
 

crutschow

Joined Mar 14, 2008
34,845
Does the actuator have limit switches?
What exactly is the purpose of the timer?
What is the timer output signal type and duration?
 

MisterBill2

Joined Jan 23, 2018
19,466
Similar topics have been covered completely on this forum in the past, and so discussions with solutions have been presented. And NO WAY am I going to provide links for them.
Certainly the only information we are provided with is that the linear actuator is DC powered and that the direction is polarity controlled.
So given that we have none of the required information to provide good advice, we await additional information, which would include the actuator voltage and current, as well as the other data requested already.
 

MaxHeadRoom

Joined Jul 18, 2013
28,831
If the linear actuator extends fully each time to each LS, which are often internal. It may require some external sense LS.
Then you just need the timer to operate the reverse relay Direction will then be dependent on which extend SW is activated.
 

Thread Starter

Lafish

Joined Feb 17, 2024
3
I am very new to circuits. The linear actuator has internal limit switches. The timer can provide a single signal for up to 8 seconds, which is enough to fully extend and retract the linear actuator. It's a 6 volt motor and 220-300mA of continuous current. So my issue as I understand it is that I have a single input from my timer and I need the actuator to extend, then retract, extend, retract, etc. My timer will be set for 6:00am, 9:00am, 3:00pm, and 6:00pm.
 

MisterBill2

Joined Jan 23, 2018
19,466
OK, I think I have got that part. The timer provides one eight second contact closure every few hours, and the linear actuator is wanted to move to it's opposite position at each contact closure. Since the actuator has limit switches to stop motion at each extreme, A guess is that reversing polarity will operate the reverse direction independent of the internal limit switch. IF THAT IS THE CASE, then a simple alternate-action maintained position relay is all that is required.
 
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