Linear Actuator control

Thread Starter

Mochdre

Joined Apr 7, 2024
4
I have a 24v DC linear actuator that I use to open and close a heavy trapdoor. It is controlled by a smart switch / PSU rated 70w @ 24v max. I need to replace the actuator with a more powerful model rated at 100w. I absolutely must keep the switch because it matches all the others I have and I can’t find anything similar that supplies more current.

My question is how can I incorporate a transformer into the system that will integrate with the DPDT smart switch which reverses polarity?
 

MaxHeadRoom

Joined Jul 18, 2013
28,829
Appears you only require one more amp of current to operate, the actuator load may, or may not actually require this much current, have you measure the current of the system with the new actuator to find out the exact current required?
Is it using a SMPS at present?
 

Thread Starter

Mochdre

Joined Apr 7, 2024
4
Appears you only require one more amp of current to operate, the actuator load may, or may not actually require this much current, have you measure the current of the system with the new actuator to find out the exact current required?
Is it using a SMPS at present?
Appears you only require one more amp of current to operate, the actuator load may, or may not actually require this much current, have you measure the current of the system with the new actuator to find out the exact current required?
Is it using a SMPS at present?
Thanks for your reply. I haven’t actually bought it yet as I’m concerned as to whether it will run or not but agree with your assertion. The SMPS is built in to the smart switch.
 

MaxHeadRoom

Joined Jul 18, 2013
28,829
What actually switches the motor current, any relays for e.g.?
I am not fond of SMPS, especially for motor control.
A linear supply, simple transformer and a bridge rect, is all that is usually needed.
 

Thread Starter

Mochdre

Joined Apr 7, 2024
4
What actually switches the motor current, any relays for e.g.?
I am not fond of SMPS, especially for motor control.
A linear supply, simple transformer and a bridge rect, is all that is usually needed.
I have a DPDT smart switch with integrated smps which has to stay.
 

MisterBill2

Joined Jan 23, 2018
19,453
OK, one simple?? option is to have that smart switch operate one of two relays to power the linear actuator in one direction or the other. That allows the switch to do the easy work with thin wires while the relays and a separate power supply do the heavy lifting.
And now it gets interesting because I think I responded on a very similar application a few months back. A heavy trap door, an actuator, and a switch that could not be changed because it matched the rest of them..

Is this a repeat? Or did that one not work out?? Or does the TS work for that "Chimera B" organization??
Or are there just a lot of folks with heavy trap doors to open???
 

Thread Starter

Mochdre

Joined Apr 7, 2024
4
OK, one simple?? option is to have that smart switch operate one of two relays to power the linear actuator in one direction or the other. That allows the switch to do the easy work with thin wires while the relays and a separate power supply do the heavy lifting.
And now it gets interesting because I think I responded on a very similar application a few months back. A heavy trap door, an actuator, and a switch that could not be changed because it matched the rest of them..

Is this a repeat? Or did that one not work out?? Or does the TS work for that "Chimera B" organization??
Or are there just a lot of folks with heavy trap doors to open???
Hi,

Thanks for the reply. Must be a coincidence as I only joined a couple of days ago! What you suggest is exactly what I need. Do you know where I could get a simple diagram with perhaps the suggestion of which relays to use?
 

MisterBill2

Joined Jan 23, 2018
19,453
The relays could be the standard automotive cube ones, with a 12 volt coil and 30 amp contacts, single pole with both NO and NC connections . That would require adjusting the power supply down from 24 volts to 12 volts, or else buying the "Big Truck" relays with 24 volt coils, and higher rated contacts.
The connections are simple: The two NC contacts tie to the actuator power supply negative side, the two NO contacts connect to the actuator supply positive side, and the two relay common connections tie to the actuator drive connections. Which gets which depends on the switch positions for open and close.
The only remaining detail is the higher capacity power supply to drive the 100 watt actuator. But at 24 volts that is less than 5 amps, so a 5 amp supply could be used, although I would choose a supply rated a bit above that.
 
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