Linear actuator
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I have a linear actuator. +12 V moves it forward, -12 V moves it back. What would be the best way to control this with a Duet 3. How do i get any of the output pins to apply -12 V to move the linear actuator back?
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@anagh maybe use a relay that is activated by an output pin to reverse the wires on the linear actuator? That way you have 12v in one state of the relay and -12V in the other relay state. This assumes the actuator has limit switches that shut off the power to the internal motor of the linear actuator at either end of travel.
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@anagh hmm would two fan ports and a custom gcode macro work?
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@anagh said in Linear actuator:
I have a linear actuator. +12 V moves it forward, -12 V moves it back.
Can you provide more info or a link to the item?
The description could apply to several different types of unit, some needing very different control to others.
Also, do you want to be able to position it accurately, or just switch between end positions?
Robert J.
Printers: Overlord pro, Kossel XL+ with Duet 6HC and "Frankentron", TronXY X5SA Pro converted to E3D toolchange with Duet 6HC and 1LC toolboards.
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@anagh
I've used a TB6612FNG dual half bridge for such application ( dc motor fwd/revers control)
The input's are 3.3V capable and the motor/actuator can run from 5-12V @1.2A. The whole circuit has flyback diodes to protect the Duet. -
@jens55 the actuator does not have limit switches. I tried to see if can use a relay to reverse polarity. One way I found was to have a combination of 3 relays. Just one relay will not cut it. will keep exploring this option though.
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@rjenkinsgb this is what I have.
https://sg.cytron.io/p-12v-micro-linear-actuator-50mm-stroke-64n
I would prefer to position it accurately. if that is not possible, I might be able to work with having it positioned at the end points. -
@anagh said in Linear actuator:
https://sg.cytron.io/p-12v-micro-linear-actuator-50mm-stroke-64n
I would prefer to position it accurately. if that is not possible, I might be able to work with having it positioned at the end points.What are you using it for?
Frederick
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@o_lampe thank you! will get one and see how it goes.
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@anagh said in Linear actuator:
this is what I have.
https://sg.cytron.io/p-12v-micro-linear-actuator-50mm-stroke-64n
I would prefer to position it accurately. if that is not possible, I might be able to work with having it positioned at the end points.If you could add a linear slide potentiometer for feedback, you could probably use the electronics from a large RC servo, substituting that motor and the pot for the originals.
It could then be positioned by a servo PWM output.
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@anagh said in Linear actuator:
@rjenkinsgb this is what I have.
https://sg.cytron.io/p-12v-micro-linear-actuator-50mm-stroke-64n
I would prefer to position it accurately. if that is not possible, I might be able to work with having it positioned at the end points.The actuator you've linked can only do full travel, but there are other versions with analog control (eg. PWM or potmeter) or RC-servo control. Maybe your vendor has them, too?
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@o_lampe can you please share how you have the setup configured. photos or details of wiring and config file would be very helpful.
I am trying to use this in my config file, but haven't had success.
M950 R1 C"out7+out8+out9" Q500 L0:20
Thanks! -
@anagh
I haven't thought of running the actuator as a spindle, but it might work.
I'd raise the L value to L0:255 for finer PWM adjustment. ( you don't know max. RPM of the motor anyway)I assume you have wired the three pins (PWM, fwd, revers) accordingly? Don't forget the Standby pin. Here's a full truth table (page 4)
Are you in CNC-mode?
Did you define a tool with that spindle and tried to run it with M3/M4/M5?It's probably useful to use a normal DC motor (not a fan) for testing, otherwise the internal endstops of the actuator can lead to confusion. Even a 12V light bulb and multimeter can help checking the fwd/revers/stop behaviour.
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@o_lampe yup. i defined the tool. ran the M3/M4/M5. but it does not seem to be working.
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Here is what worked for me. I used 2 of these relays.
https://www.amazon.com/gp/product/B09FPVGC5V/ref=ppx_yo_dt_b_asin_image_o00_s00?ie=UTF8&psc=1
Key is to make sure relays have 2 pins for input, not just one input pin like the typical relay modules have.Once you have these, you can create an H-bridge. Diagram 2 in the following link.
https://mechatrofice.com/circuits/relay-dc-motor-driver
Each of the relay can then be controlled to switch the direction of the motor. I hope this helps someone with a similar need. -
@anagh I'm glad you got it working. Using either a relay H-bridge or an H-bridge IC is the correct approach. There are boards using the ancient L298N IC readily available that I think would be suitable, if the actuator draws 2A or less. Also the TB6612FNG device mentioned by @o_lampe for up to 1.2A.
