RB-Fir-121 operation

Help & Support Robot Parts
1

I’m using RB-Fir-103 and RB-Fir-121 to move a lcd screen up out of the dashboard of a car. I would like to send a 12V (or it could be ground) signal to the controller which will in turn extend the actuator to its longest point and hold it there as long as the 12 V signal is applied, then when the 12V signal is removed, the actuator retracts to its fully closed position. So, my questions is, will RB-Fir-121 enable me to do this?

2

Hey @ksungela!

Unfortunately, the LAC (Fir-121), cannot be operated that way.
However, if you hook-up an op-amp to lower your 0-12V signal to 0-3.3V and then send that signal to pin 5 of the X6 terminal, it will work just fine.
Source: https://www.robotshop.com/media/files/pdf2/actuonix_lac_datasheet.pdf

3

Thank you. Can you recommend a specific op-amp to use and provide a simple wiring diagram to show it would be hooked up?

4

You would essentially need a non inverting differential amplifier setup with a gain of 0.275. I’ve added a quick sketch of the wiring made on https://www.daycounter.com/Calculators/Op-Amp/Op-Amp-Voltage-Calculator.phtml below

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GreatScott has a nice series on electronics. One of the episodes shows how op-amps work.

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5

Thanks again. This device might do the trick? What do you think?

6

This one goes up to 3V, not 3.3V. You would have to check how much the actuator expands at 3V and if it is enough for your use.

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7

Now I’m confused, I thought X3 pin2 would get 12V which would also power the actuator at 12V and X6 pin5 would get the scaled down voltage of 3V just as a trigger signal. Your post implies the actuator would only get the voltage that’s applied to x6 pin 5, or am I misunderstanding?

8

Hey @ksungela

I just noticed but you are using a linear actuator without any feedback. There’s no need for the LAC since there are limit swtiches on your actuator.
Once the actuator has reached the end of it’s course, it will turn off automatically. You only need to reverse the polarity to retract it.
You could simply use a DPDT switch or relay to operate it

This actuator is not compatible with the LAC

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